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Altair 680 expander boards

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  • mfeberhard
    Since the subject of 680 replicas came up again, I thought I d bring this up: A while back, I designed and fabricated a small run of replica expander boards
    Message 1 of 15 , Sep 11, 2013
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      Since the subject of 680 replicas came up again, I thought I'd bring this up:

      A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

      These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

      I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

      If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

      Let me know if you are interested.
    • John Crane
      That s great news. I d like 2 backplanes with full connectors, please. -John Garza ... On Wed, 9/11/13, eberhard@allenroad.com wrote:
      Message 2 of 15 , Sep 11, 2013
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        That's great news.

        I'd like 2 backplanes with full connectors, please.

        -John Garza
        --------------------------------------------
        On Wed, 9/11/13, eberhard@... <eberhard@...> wrote:

        Subject: [Altair Computer Club] Altair 680 expander boards
        To: altaircomputerclub@yahoogroups.com
        Date: Wednesday, September 11, 2013, 4:33 PM
















         









        Since the subject of 680 replicas came up again, I
        thought I'd bring this up:

        A while back, I designed and fabricated a small run of
        replica expander boards (backplanes) for the Altair 680.
        They are a pretty close replica, and have decent gold
        plating on the fingers, both top and bottom. You can see
        photos of my expander board in the Files section, under
        "Altair 680b Expander Board".

        These work great - that's what I have in my own 680b.
        with brand-new edge connectors, all of the usual flakiness
        problems of my 680b went away.

        I still have a few of these left, if anyone wants to buy
        one. I will sell them for $30 each without the edge
        connectors installed - they take the same edge connectors as
        all other Altair backplanes.

        If you want to buy edge connectors, I will place an order
        for them - they cost about $12 each, the last time I looked,
        and they take several weeks to be delivered.

        Let me know if you are interested.
      • mfeberhard
        The best-match connector for these (and for all other Altair backplanes) is the Sullins EBA50DRTH, available from Digikey here:
        Message 3 of 15 , Sep 11, 2013
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          The best-match connector for these (and for all other Altair backplanes) is the Sullins EBA50DRTH, available from Digikey here:

          http://www.digikey.com/product-detail/en/EBA50DRTH/EBA50DRTH-ND/973832

          The only thing really wrong with these connectors is that Sullins now prints their %@#$% website URL on the connectors. I am sure someone among us can find the right chemistry to remove this printing!

          There is a minimum order quantity, and they take a bit of time to arrive.

           



          --- In altaircomputerclub@yahoogroups.com, <john_crane_59@...> wrote:

          That's great news.

          I'd like 2 backplanes with full connectors, please.

          -John Garza
          --------------------------------------------
          On Wed, 9/11/13, eberhard@... <eberhard@...> wrote:

          Subject: [Altair Computer Club] Altair 680 expander boards
          To: altaircomputerclub@yahoogroups.com
          Date: Wednesday, September 11, 2013, 4:33 PM
















           









          Since the subject of 680 replicas came up again, I
          thought I'd bring this up:

          A while back, I designed and fabricated a small run of
          replica expander boards (backplanes) for the Altair 680.
          They are a pretty close replica, and have decent gold
          plating on the fingers, both top and bottom. You can see
          photos of my expander board in the Files section, under
          "Altair 680b Expander Board".

          These work great - that's what I have in my own 680b.
          with brand-new edge connectors, all of the usual flakiness
          problems of my 680b went away.

          I still have a few of these left, if anyone wants to buy
          one. I will sell them for $30 each without the edge
          connectors installed - they take the same edge connectors as
          all other Altair backplanes.

          If you want to buy edge connectors, I will place an order
          for them - they cost about $12 each, the last time I looked,
          and they take several weeks to be delivered.

          Let me know if you are interested.
        • mfeberhard
          Well THAT didn t take long! All the 680 backplanes are gone. If there s ever enough interest for more, I can get them fabricated. The order starts to make
          Message 4 of 15 , Sep 11, 2013
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            Well THAT didn't take long! All the 680 backplanes are gone. If there's ever enough interest for more, I can get them fabricated. The order starts to make sense with about 10 backplanes.

            On a related note,:

            The expander board is designed to take an edge connector on its top too. If you put one there, then you can stand a board on top, while you are debugging - very handy.

            This position requires a different connector - it's like the ones that go on an extender card. What's really cool is that this connector will stay in place on the board and make good contact without soldering - it's friction fit is tight. So you can take it off again if you want.

            The best connector for this position is the EDAC 346-100-555-804. I think you can special-order these from Mouser. (I can't remember where I bought mine.)

             



            --- In altaircomputerclub@yahoogroups.com, <eberhard@...> wrote:

            The best-match connector for these (and for all other Altair backplanes) is the Sullins EBA50DRTH, available from Digikey here:

            http://www.digikey.com/product-detail/en/EBA50DRTH/EBA50DRTH-ND/973832

            The only thing really wrong with these connectors is that Sullins now prints their %@#$% website URL on the connectors. I am sure someone among us can find the right chemistry to remove this printing!

            There is a minimum order quantity, and they take a bit of time to arrive.

             



            --- In altaircomputerclub@yahoogroups.com, <john_crane_59@...> wrote:

            That's great news.

            I'd like 2 backplanes with full connectors, please.

            -John Garza
            --------------------------------------------
            On Wed, 9/11/13, eberhard@... <eberhard@...> wrote:

            Subject: [Altair Computer Club] Altair 680 expander boards
            To: altaircomputerclub@yahoogroups.com
            Date: Wednesday, September 11, 2013, 4:33 PM
















             









            Since the subject of 680 replicas came up again, I
            thought I'd bring this up:

            A while back, I designed and fabricated a small run of
            replica expander boards (backplanes) for the Altair 680.
            They are a pretty close replica, and have decent gold
            plating on the fingers, both top and bottom. You can see
            photos of my expander board in the Files section, under
            "Altair 680b Expander Board".

            These work great - that's what I have in my own 680b.
            with brand-new edge connectors, all of the usual flakiness
            problems of my 680b went away.

            I still have a few of these left, if anyone wants to buy
            one. I will sell them for $30 each without the edge
            connectors installed - they take the same edge connectors as
            all other Altair backplanes.

            If you want to buy edge connectors, I will place an order
            for them - they cost about $12 each, the last time I looked,
            and they take several weeks to be delivered.

            Let me know if you are interested.
          • Kip Koon
            Hi Guys! I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards, I thought
            Message 5 of 15 , Sep 11, 2013
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              Hi Guys!

              I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

              Kip

               

              From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
              Sent: Wednesday, September 11, 2013 7:34 PM
              To: altaircomputerclub@yahoogroups.com
              Subject: [Altair Computer Club] Altair 680 expander boards

               

               

              Since the subject of 680 replicas came up again, I thought I'd bring this up:

              A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

              These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

              I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

              If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

              Let me know if you are interested.

            • mfeberhard
              Kip, The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one expansion socket, which was intended
              Message 6 of 15 , Sep 11, 2013
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                Kip,

                The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                680-KCACR cassette interface
                680-BSM 16K static RAM
                680-PCI Process Control Interface
                680-UIO 2 serial plus 2 parallel ports

                There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                 



                --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                Hi Guys!

                I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                Kip

                 

                From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                Sent: Wednesday, September 11, 2013 7:34 PM
                To: altaircomputerclub@yahoogroups.com
                Subject: [Altair Computer Club] Altair 680 expander boards

                 

                 

                Since the subject of 680 replicas came up again, I thought I'd bring this up:

                A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                Let me know if you are interested.

              • Kip Koon
                Hi eberhard! I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b. In an effort to make the 680b that best it could
                Message 7 of 15 , Sep 12, 2013
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                  Hi eberhard!

                  I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b.  In an effort to make the 680b that best it could be, has anyone expanded on the design to take advantage of higher cpu clock rates, more memory, various storage capabilities, various communications methods and other improvements to enhance the 680(b) series?   They did the absolute best with what was available back then, so how about upgrading the 680b and taking advantage of the absolute best of what is available now?  I for one am all for it!

                  Kip

                   

                  From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                  Sent: Thursday, September 12, 2013 2:37 AM
                  To: altaircomputerclub@yahoogroups.com
                  Subject: RE: [Altair Computer Club] Altair 680 expander boards

                   

                   

                  Kip,

                  The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                  As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                  Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                  With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                  680-KCACR cassette interface
                  680-BSM 16K static RAM
                  680-PCI Process Control Interface
                  680-UIO 2 serial plus 2 parallel ports

                  There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                   



                  --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                  Hi Guys!

                  I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                  Kip

                   

                  From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                  Sent: Wednesday, September 11, 2013 7:34 PM
                  To: altaircomputerclub@yahoogroups.com
                  Subject: [Altair Computer Club] Altair 680 expander boards

                   

                   

                  Since the subject of 680 replicas came up again, I thought I'd bring this up:

                  A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                  These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                  I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                  If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                  Let me know if you are interested.

                • wtsnet
                  Kip, Martin, Grant and 680 fans: As far as I know, Grant s 680 is more than a true-to-the-original replica of the original Altair. The replica is fully
                  Message 8 of 15 , Sep 12, 2013
                  • 0 Attachment
                    Kip, Martin, Grant and 680 fans:

                    As far as I know, Grant's 680 is more than a true-to-the-original replica of the original Altair. The replica is fully compatible with some cosmetic improvements and a good switching power supply. According to Computer Notes, expansion boards require a power supply upgrade.

                    Grant made an innovative expansion module that used the CPU socket to interface. The module included ram and more. Last I heard a revised design was planned. I mention this pioneering work, because expansion boards are rare. Experience with memory boards indicates MITS chip sockets are inferior to modern replacements.The Rev1 memory Mod may not be well documented.

                    I like Kip, Martin, and Grants ideas of 680 expansion. Memory is likely the first issue. If MITS memory works, it would still fill the expansion slots to get to 48K.

                    Here is a warning about board spacing. Don't ask how I learned that the board spacer size is important. Too short and the first board shorts pins to the clock crystal metal cover.

                    W. Tom S.

                     



                    --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                    Hi eberhard!

                    I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b.  In an effort to make the 680b that best it could be, has anyone expanded on the design to take advantage of higher cpu clock rates, more memory, various storage capabilities, various communications methods and other improvements to enhance the 680(b) series?   They did the absolute best with what was available back then, so how about upgrading the 680b and taking advantage of the absolute best of what is available now?  I for one am all for it!

                    Kip

                     

                    From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                    Sent: Thursday, September 12, 2013 2:37 AM
                    To: altaircomputerclub@yahoogroups.com
                    Subject: RE: [Altair Computer Club] Altair 680 expander boards

                     

                     

                    Kip,

                    The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                    As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                    Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                    With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                    680-KCACR cassette interface
                    680-BSM 16K static RAM
                    680-PCI Process Control Interface
                    680-UIO 2 serial plus 2 parallel ports

                    There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                     



                    --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                    Hi Guys!

                    I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                    Kip

                     

                    From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                    Sent: Wednesday, September 11, 2013 7:34 PM
                    To: altaircomputerclub@yahoogroups.com
                    Subject: [Altair Computer Club] Altair 680 expander boards

                     

                     

                    Since the subject of 680 replicas came up again, I thought I'd bring this up:

                    A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                    These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                    I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                    If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                    Let me know if you are interested.

                  • mfeberhard
                    When debugging my own 680b, I was actually a little surprised at how poorly engineered it was. I know it is not fair to use today s engineering as a yardstick
                    Message 9 of 15 , Sep 12, 2013
                    • 0 Attachment
                      When debugging my own 680b, I was actually a little surprised at how poorly engineered it was. I know it is not fair to use today's engineering as a yardstick to measure 1970s designs, but still...

                      I can't see any reason why they ran the 6800 at 500 KHz - it should have been easy to run it at 1 MHz. I ran across a few older 680 boards that looked like they came from within MITS. These boards hinted that MITS was experimenting with a design change to bump the clock rate up to 1 MHz.

                      I became familiar with the Motorola 6800 CPU in the early 1980s, when I designed the Wyse WY-30 terminal. The WY-30 is based on the 6800b (at 2 MHz), and its design takes advantage of the 2-phase nature of the 6800's bus. If you do it right, the 6800 only needs the bus during one phase of its cycle. During the other phase, the bus is available for DMA operations. In the case of the WY-30, I used the 2nd bus phase for updating the video display, using the Motorola 6845 CRT controller. Thus, the CRT controller's constant memory accesses do not have any effect on CPU performance - these DMA reads are completely hidden: cheap and fast.

                      I thought that this aspect of the 6800 microprocessor or would create the opportunity for a high-performance DMA-based floppy disk controller - the 6800 could keep running even while data is written to or read from the disk.

                      Unfortunately, the processor and memory in the Altair 680b hog the bus during both phases of the clock. This was done to keep the LEDs on the front panel lit during both clock phases. This shortcut basically saved them a couple of data latches on the front panel. Bummer.

                      I do think it would be possible to design such a DMA disk controller for the 680bt (no front panel), with some modifications to the main board and the memory boards. But the front panel is half the appeal of these things to me :-)

                       



                      --- In altaircomputerclub@yahoogroups.com, <yahoo@...> wrote:

                      Kip, Martin, Grant and 680 fans:

                      As far as I know, Grant's 680 is more than a true-to-the-original replica of the original Altair. The replica is fully compatible with some cosmetic improvements and a good switching power supply. According to Computer Notes, expansion boards require a power supply upgrade.

                      Grant made an innovative expansion module that used the CPU socket to interface. The module included ram and more. Last I heard a revised design was planned. I mention this pioneering work, because expansion boards are rare. Experience with memory boards indicates MITS chip sockets are inferior to modern replacements.The Rev1 memory Mod may not be well documented.

                      I like Kip, Martin, and Grants ideas of 680 expansion. Memory is likely the first issue. If MITS memory works, it would still fill the expansion slots to get to 48K.

                      Here is a warning about board spacing. Don't ask how I learned that the board spacer size is important. Too short and the first board shorts pins to the clock crystal metal cover.

                      W. Tom S.

                       



                      --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                      Hi eberhard!

                      I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b.  In an effort to make the 680b that best it could be, has anyone expanded on the design to take advantage of higher cpu clock rates, more memory, various storage capabilities, various communications methods and other improvements to enhance the 680(b) series?   They did the absolute best with what was available back then, so how about upgrading the 680b and taking advantage of the absolute best of what is available now?  I for one am all for it!

                      Kip

                       

                      From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                      Sent: Thursday, September 12, 2013 2:37 AM
                      To: altaircomputerclub@yahoogroups.com
                      Subject: RE: [Altair Computer Club] Altair 680 expander boards

                       

                       

                      Kip,

                      The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                      As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                      Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                      With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                      680-KCACR cassette interface
                      680-BSM 16K static RAM
                      680-PCI Process Control Interface
                      680-UIO 2 serial plus 2 parallel ports

                      There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                       



                      --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                      Hi Guys!

                      I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                      Kip

                       

                      From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                      Sent: Wednesday, September 11, 2013 7:34 PM
                      To: altaircomputerclub@yahoogroups.com
                      Subject: [Altair Computer Club] Altair 680 expander boards

                       

                       

                      Since the subject of 680 replicas came up again, I thought I'd bring this up:

                      A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                      These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                      I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                      If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                      Let me know if you are interested.

                    • B Degnan
                      might then would the turnkey model be easier to work with to bring to 1mhz? ... From: eberhard To: altaircomputerclub
                      Message 10 of 15 , Sep 12, 2013
                      • 0 Attachment
                        might then would the turnkey model be easier to work with to bring to 1mhz?



                        -----Original Message-----
                        From: eberhard <eberhard@...>
                        To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                        Sent: Thu, Sep 12, 2013 10:53 am
                        Subject: [Altair Computer Club] RE: Altair 680 expander boards



                        When debugging my own 680b, I was actually a little surprised at how poorly engineered it was. I know it is not fair to use today's engineering as a yardstick to measure 1970s designs, but still...

                        I can't see any reason why they ran the 6800 at 500 KHz - it should have been easy to run it at 1 MHz. I ran across a few older 680 boards that looked like they came from within MITS. These boards hinted that MITS was experimenting with a design change to bump the clock rate up to 1 MHz.

                        I became familiar with the Motorola 6800 CPU in the early 1980s, when I designed the Wyse WY-30 terminal. The WY-30 is based on the 6800b (at 2 MHz), and its design takes advantage of the 2-phase nature of the 6800's bus. If you do it right, the 6800 only needs the bus during one phase of its cycle. During the other phase, the bus is available for DMA operations. In the case of the WY-30, I used the 2nd bus phase for updating the video display, using the Motorola 6845 CRT controller. Thus, the CRT controller's constant memory accesses do not have any effect on CPU performance - these DMA reads are completely hidden: cheap and fast.

                        I thought that this aspect of the 6800 microprocessor or would create the opportunity for a high-performance DMA-based floppy disk controller - the 6800 could keep running even while data is written to or read from the disk.

                        Unfortunately, the processor and memory in the Altair 680b hog the bus during both phases of the clock. This was done to keep the LEDs on the front panel lit during both clock phases. This shortcut basically saved them a couple of data latches on the front panel. Bummer.

                        I do think it would be possible to design such a DMA disk controller for the 680bt (no front panel), with some modifications to the main board and the memory boards. But the front panel is half the appeal of these things to me :-)
                         


                        --- In altaircomputerclub@yahoogroups.com, <yahoo@...> wrote:

                        Kip, Martin, Grant and 680 fans:

                        As far as I know, Grant's 680 is more than a true-to-the-original replica of the original Altair. The replica is fully compatible with some cosmetic improvements and a good switching power supply. According to Computer Notes, expansion boards require a power supply upgrade.

                        Grant made an innovative expansion module that used the CPU socket to interface. The module included ram and more. Last I heard a revised design was planned. I mention this pioneering work, because expansion boards are rare. Experience with memory boards indicates MITS chip sockets are inferior to modern replacements.The Rev1 memory Mod may not be well documented.

                        I like Kip, Martin, and Grants ideas of 680 expansion. Memory is likely the first issue. If MITS memory works, it would still fill the expansion slots to get to 48K.

                        Here is a warning about board spacing. Don't ask how I learned that the board spacer size is important. Too short and the first board shorts pins to the clock crystal metal cover.

                        W. Tom S.
                         


                        --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                        Hi eberhard!
                        I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b.  In an effort to make the 680b that best it could be, has anyone expanded on the design to take advantage of higher cpu clock rates, more memory, various storage capabilities, various communications methods and other improvements to enhance the 680(b) series?   They did the absolute best with what was available back then, so how about upgrading the 680b and taking advantage of the absolute best of what is available now?  I for one am all for it!
                        Kip
                         
                        From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                        Sent: Thursday, September 12, 2013 2:37 AM
                        To: altaircomputerclub@yahoogroups.com
                        Subject: RE: [Altair Computer Club] Altair 680 expander boards
                         
                         
                        Kip,

                        The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                        As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                        Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                        With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                        680-KCACR cassette interface
                        680-BSM 16K static RAM
                        680-PCI Process Control Interface
                        680-UIO 2 serial plus 2 parallel ports

                        There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)
                         
                        Hi Guys!
                        I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.
                        Kip
                         
                        From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                        Sent: Wednesday, September 11, 2013 7:34 PM
                        To: altaircomputerclub@yahoogroups.com
                        Subject: [Altair Computer Club] Altair 680 expander boards
                         
                         
                        Since the subject of 680 replicas came up again, I thought I'd bring this up:

                        A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                        These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                        I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                        If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                        Let me know if you are interested.


                      • wtsnet
                        As far as I know the motherboard is the same for Turnkey and Front Panel 680.. --- In altaircomputerclub@yahoogroups.com,
                        Message 11 of 15 , Sep 12, 2013
                        • 0 Attachment

                          As far as I know the motherboard is the same for Turnkey and Front Panel 680.. 



                          --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                          might then would the turnkey model be easier to work with to bring to 1mhz?



                          -----Original Message-----
                          From: eberhard <eberhard@...>
                          To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                          Sent: Thu, Sep 12, 2013 10:53 am
                          Subject: [Altair Computer Club] RE: Altair 680 expander boards



                          When debugging my own 680b, I was actually a little surprised at how poorly engineered it was. I know it is not fair to use today's engineering as a yardstick to measure 1970s designs, but still...

                          I can't see any reason why they ran the 6800 at 500 KHz - it should have been easy to run it at 1 MHz. I ran across a few older 680 boards that looked like they came from within MITS. These boards hinted that MITS was experimenting with a design change to bump the clock rate up to 1 MHz.

                          I became familiar with the Motorola 6800 CPU in the early 1980s, when I designed the Wyse WY-30 terminal. The WY-30 is based on the 6800b (at 2 MHz), and its design takes advantage of the 2-phase nature of the 6800's bus. If you do it right, the 6800 only needs the bus during one phase of its cycle. During the other phase, the bus is available for DMA operations. In the case of the WY-30, I used the 2nd bus phase for updating the video display, using the Motorola 6845 CRT controller. Thus, the CRT controller's constant memory accesses do not have any effect on CPU performance - these DMA reads are completely hidden: cheap and fast.

                          I thought that this aspect of the 6800 microprocessor or would create the opportunity for a high-performance DMA-based floppy disk controller - the 6800 could keep running even while data is written to or read from the disk.

                          Unfortunately, the processor and memory in the Altair 680b hog the bus during both phases of the clock. This was done to keep the LEDs on the front panel lit during both clock phases. This shortcut basically saved them a couple of data latches on the front panel. Bummer.

                          I do think it would be possible to design such a DMA disk controller for the 680bt (no front panel), with some modifications to the main board and the memory boards. But the front panel is half the appeal of these things to me :-)
                           


                          --- In altaircomputerclub@yahoogroups.com, <yahoo@...> wrote:

                          Kip, Martin, Grant and 680 fans:

                          As far as I know, Grant's 680 is more than a true-to-the-original replica of the original Altair. The replica is fully compatible with some cosmetic improvements and a good switching power supply. According to Computer Notes, expansion boards require a power supply upgrade.

                          Grant made an innovative expansion module that used the CPU socket to interface. The module included ram and more. Last I heard a revised design was planned. I mention this pioneering work, because expansion boards are rare. Experience with memory boards indicates MITS chip sockets are inferior to modern replacements.The Rev1 memory Mod may not be well documented.

                          I like Kip, Martin, and Grants ideas of 680 expansion. Memory is likely the first issue. If MITS memory works, it would still fill the expansion slots to get to 48K.

                          Here is a warning about board spacing. Don't ask how I learned that the board spacer size is important. Too short and the first board shorts pins to the clock crystal metal cover.

                          W. Tom S.
                           


                          --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                          Hi eberhard!
                          I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b.  In an effort to make the 680b that best it could be, has anyone expanded on the design to take advantage of higher cpu clock rates, more memory, various storage capabilities, various communications methods and other improvements to enhance the 680(b) series?   They did the absolute best with what was available back then, so how about upgrading the 680b and taking advantage of the absolute best of what is available now?  I for one am all for it!
                          Kip
                           
                          From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                          Sent: Thursday, September 12, 2013 2:37 AM
                          To: altaircomputerclub@yahoogroups.com
                          Subject: RE: [Altair Computer Club] Altair 680 expander boards
                           
                           
                          Kip,

                          The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                          As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                          Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                          With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                          680-KCACR cassette interface
                          680-BSM 16K static RAM
                          680-PCI Process Control Interface
                          680-UIO 2 serial plus 2 parallel ports

                          There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)
                           
                          Hi Guys!
                          I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.
                          Kip
                           
                          From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                          Sent: Wednesday, September 11, 2013 7:34 PM
                          To: altaircomputerclub@yahoogroups.com
                          Subject: [Altair Computer Club] Altair 680 expander boards
                           
                           
                          Since the subject of 680 replicas came up again, I thought I'd bring this up:

                          A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                          These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                          I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                          If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                          Let me know if you are interested.


                        • B Degnan
                          What I mean is that without having to worry about the front panel on the turnkey, you can mess with the motherboard without impact to the non-existent
                          Message 12 of 15 , Sep 12, 2013
                          • 0 Attachment
                            What I mean is that without having to worry about the front panel on the turnkey, you can mess with the motherboard without impact to the non-existent motherboard.

                            Did you see the 1977 MITS catalog I uploaded yesterday?  Lots of boards included.  Some I never saw before.

                            Bill




                            -----Original Message-----
                            From: yahoo <yahoo@...>
                            To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                            Sent: Thu, Sep 12, 2013 11:09 am
                            Subject: RE: Re: [Altair Computer Club] RE: Altair 680 expander boards



                            As far as I know the motherboard is the same for Turnkey and Front Panel 680.. 


                            --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                            might then would the turnkey model be easier to work with to bring to 1mhz?



                            -----Original Message-----
                            From: eberhard <eberhard@...>
                            To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                            Sent: Thu, Sep 12, 2013 10:53 am
                            Subject: [Altair Computer Club] RE: Altair 680 expander boards



                            When debugging my own 680b, I was actually a little surprised at how poorly engineered it was. I know it is not fair to use today's engineering as a yardstick to measure 1970s designs, but still...

                            I can't see any reason why they ran the 6800 at 500 KHz - it should have been easy to run it at 1 MHz. I ran across a few older 680 boards that looked like they came from within MITS. These boards hinted that MITS was experimenting with a design change to bump the clock rate up to 1 MHz.

                            I became familiar with the Motorola 6800 CPU in the early 1980s, when I designed the Wyse WY-30 terminal. The WY-30 is based on the 6800b (at 2 MHz), and its design takes advantage of the 2-phase nature of the 6800's bus. If you do it right, the 6800 only needs the bus during one phase of its cycle. During the other phase, the bus is available for DMA operations. In the case of the WY-30, I used the 2nd bus phase for updating the video display, using the Motorola 6845 CRT controller. Thus, the CRT controller's constant memory accesses do not have any effect on CPU performance - these DMA reads are completely hidden: cheap and fast.

                            I thought that this aspect of the 6800 microprocessor or would create the opportunity for a high-performance DMA-based floppy disk controller - the 6800 could keep running even while data is written to or read from the disk.

                            Unfortunately, the processor and memory in the Altair 680b hog the bus during both phases of the clock. This was done to keep the LEDs on the front panel lit during both clock phases. This shortcut basically saved them a couple of data latches on the front panel. Bummer.

                            I do think it would be possible to design such a DMA disk controller for the 680bt (no front panel), with some modifications to the main board and the memory boards. But the front panel is half the appeal of these things to me :-)
                             


                            --- In altaircomputerclub@yahoogroups.com, <yahoo@...> wrote:

                            Kip, Martin, Grant and 680 fans:

                            As far as I know, Grant's 680 is more than a true-to-the-original replica of the original Altair. The replica is fully compatible with some cosmetic improvements and a good switching power supply. According to Computer Notes, expansion boards require a power supply upgrade.

                            Grant made an innovative expansion module that used the CPU socket to interface. The module included ram and more. Last I heard a revised design was planned. I mention this pioneering work, because expansion boards are rare. Experience with memory boards indicates MITS chip sockets are inferior to modern replacements.The Rev1 memory Mod may not be well documented.

                            I like Kip, Martin, and Grants ideas of 680 expansion. Memory is likely the first issue. If MITS memory works, it would still fill the expansion slots to get to 48K.

                            Here is a warning about board spacing. Don't ask how I learned that the board spacer size is important. Too short and the first board shorts pins to the clock crystal metal cover.

                            W. Tom S.
                             


                            --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                            Hi eberhard!
                            I certainly understand the appeal of a true-to-the-original replica of the Altair 680 and 680b.  In an effort to make the 680b that best it could be, has anyone expanded on the design to take advantage of higher cpu clock rates, more memory, various storage capabilities, various communications methods and other improvements to enhance the 680(b) series?   They did the absolute best with what was available back then, so how about upgrading the 680b and taking advantage of the absolute best of what is available now?  I for one am all for it!
                            Kip
                             
                            From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                            Sent: Thursday, September 12, 2013 2:37 AM
                            To: altaircomputerclub@yahoogroups.com
                            Subject: RE: [Altair Computer Club] Altair 680 expander boards
                             
                             
                            Kip,

                            The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                            As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                            Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                            With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                            680-KCACR cassette interface
                            680-BSM 16K static RAM
                            680-PCI Process Control Interface
                            680-UIO 2 serial plus 2 parallel ports

                            There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)
                             
                            Hi Guys!
                            I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.
                            Kip
                             
                            From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                            Sent: Wednesday, September 11, 2013 7:34 PM
                            To: altaircomputerclub@yahoogroups.com
                            Subject: [Altair Computer Club] Altair 680 expander boards
                             
                             
                            Since the subject of 680 replicas came up again, I thought I'd bring this up:

                            A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                            These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                            I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                            If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                            Let me know if you are interested.





                          • B Degnan
                            A separate transformer would be needed to power three additional cards.  Right? Bill Sent from AOL Mobile Mail ... From: eberhard To:
                            Message 13 of 15 , Sep 12, 2013
                            • 0 Attachment
                              A separate transformer would be needed to power three additional cards.  Right?
                              Bill

                              Sent from AOL Mobile Mail


                              -----Original Message-----
                              From: eberhard <eberhard@...>
                              To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                              Sent: Thu, Sep 12, 2013 05:07 PM
                              Subject: RE: [Altair Computer Club] Altair 680 expander boards




                              Kip,

                              The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                              As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                              Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                              With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                              680-KCACR cassette interface
                              680-BSM 16K static RAM
                              680-PCI Process Control Interface
                              680-UIO 2 serial plus 2 parallel ports

                              There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                               



                              --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                              Hi Guys!

                              I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                              Kip

                               

                              From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                              Sent: Wednesday, September 11, 2013 7:34 PM
                              To: altaircomputerclub@yahoogroups.com
                              Subject: [Altair Computer Club] Altair 680 expander boards

                               

                               

                              Since the subject of 680 replicas came up again, I thought I'd bring this up:

                              A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                              These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                              I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                              If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                              Let me know if you are interested.



                            • Martin Eberhard
                              Not really. Mine works great with the original power supply. I have 2 16K SRAM boards and a UIO. I checked out the voltage regulation, and it looks fine. It is
                              Message 14 of 15 , Sep 12, 2013
                              • 0 Attachment
                                Not really. Mine works great with the original power supply. I have 2 16K SRAM boards and a UIO. I checked out the voltage regulation, and it looks fine.

                                It is possible that if you had the 680-PCI board (with a bunch of relays) and also had a low-line condition on the 120V input, you might have a problem.

                                My 680B actually had the 2nd transformer hack. But it was so hokey that I took it out, never imagining that this was an official factory hack :-)

                                Martin


                                On Thu, Sep 12, 2013 at 2:35 PM, B Degnan <billdeg@...> wrote:
                                 

                                A separate transformer would be needed to power three additional cards.  Right?

                                Bill

                                Sent from AOL Mobile Mail


                                -----Original Message-----
                                From: eberhard <eberhard@...>
                                To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                                Sent: Thu, Sep 12, 2013 05:07 PM
                                Subject: RE: [Altair Computer Club] Altair 680 expander boards




                                Kip,

                                The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                                As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                                Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                                With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                                680-KCACR cassette interface
                                680-BSM 16K static RAM
                                680-PCI Process Control Interface
                                680-UIO 2 serial plus 2 parallel ports

                                There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                                 



                                --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                                Hi Guys!

                                I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                                Kip

                                 

                                From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                                Sent: Wednesday, September 11, 2013 7:34 PM
                                To: altaircomputerclub@yahoogroups.com
                                Subject: [Altair Computer Club] Altair 680 expander boards

                                 

                                 

                                Since the subject of 680 replicas came up again, I thought I'd bring this up:

                                A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                                These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                                I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                                If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                                Let me know if you are interested.




                              • wtsnet
                                A Computer Notes article describes how to add a second transformer. I was told the transformer is no longer available. The clone 680 has a new back panel
                                Message 15 of 15 , Sep 12, 2013
                                • 0 Attachment

                                  A Computer Notes article describes how to add a second transformer. I was told the transformer is no longer available. The clone 680 has a new back panel design for use with a switching supply.



                                  --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                                  A separate transformer would be needed to power three additional cards.  Right?
                                  Bill

                                  Sent from AOL Mobile Mail


                                  -----Original Message-----
                                  From: eberhard <eberhard@...>
                                  To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                                  Sent: Thu, Sep 12, 2013 05:07 PM
                                  Subject: RE: [Altair Computer Club] Altair 680 expander boards




                                  Kip,

                                  The Altair 680 was a low-cost product with limited expansion capability. In its base configuration, it had just one  expansion socket, which was intended only to take an "expansion board" - which was sold separately. Many (most?) Altair 680s and 680bs were sold without this expansion board, and were thus limited to 1K RAM, and 1 serial port.

                                  As far as I know, the excellent Grant Stockley replica is just that - a true-to-the-original replica of the original Altair, including the connector that would take an expansion board. I don't think Grant offered an expansion board for sale with his kit, (and I am sure someone here will educate me if I am wrong on this).

                                  Because so many 680s were originally sold without expansion boards, they are pretty scarce. This is why I decided to create a copy of the original Altair 680b expansion board. I am pretty sure that my expansion board, just like an original expansion board, will work perfectly in Grant's replica, just as it does in a real Altair 680 or 680b.

                                  With an expansion board, the Altair 680 - Grant's replica or original - will have 3 expansion sockets. I know of the following option boards that were made available for the 680b:

                                  680-KCACR cassette interface
                                  680-BSM 16K static RAM
                                  680-PCI Process Control Interface
                                  680-UIO 2 serial plus 2 parallel ports

                                  There was rumor of a floppy controller for the 680b, but to my knowledge, such a board was never offered for sale by MITS. (I think it is even doubtful that the 6800 processor, running at 500 KHz as it does in the Altair 680b, can even keep up with even a minidisk data rate.)

                                   



                                  --- In altaircomputerclub@yahoogroups.com, <altaircomputerclub@yahoogroups.com> wrote:

                                  Hi Guys!

                                  I have been a longtime admirer of the Motorola line of microprocessors and when I saw the discussion of the Altair 680 expander boards,  I thought interesting.  Hmmm, I would like to know want it would take to build a complete 680b computer system with expansion capabilities using the newest technology available.  I’m not really aware of what is currently available for the 680b and maybe later a 6809 or 6309 version.  I have seen 680b replicas before, that although very well done, had everything on one PCB with no expansion capabilities.  This design for the 680b did not interest me.  However, with the talk of expansion boards, I am again interested.  Any help with this endeavor will be much appreciated.  Thank you in advance.

                                  Kip

                                   

                                  From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of eberhard@...
                                  Sent: Wednesday, September 11, 2013 7:34 PM
                                  To: altaircomputerclub@yahoogroups.com
                                  Subject: [Altair Computer Club] Altair 680 expander boards

                                   

                                   

                                  Since the subject of 680 replicas came up again, I thought I'd bring this up:

                                  A while back, I designed and fabricated a small run of replica expander boards (backplanes) for the Altair 680. They are a pretty close replica, and have decent gold plating on the fingers, both top and bottom. You can see photos of my expander board in the Files section, under "Altair 680b Expander Board".

                                  These work great - that's what I have in my own 680b. with brand-new edge connectors, all of the usual flakiness problems of my 680b went away.

                                  I still have a few of these left, if anyone wants to buy one. I will sell them for $30 each without the edge connectors installed - they take the same edge connectors as all other Altair backplanes.

                                  If you want to buy edge connectors, I will place an order for them - they cost about $12 each, the last time I looked, and they take several weeks to be delivered.

                                  Let me know if you are interested.



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