Loading ...
Sorry, an error occurred while loading the content.

Re: [Altair Computer Club] Digest Number 258

Expand Messages
  • Dave Sroelov
    steve, i think the biggest niggly little gremlin i had was the original clock circuitry. when the first load came out of the factory, the clock circuit was
    Message 1 of 11 , May 13, 2006
    • 0 Attachment
      steve,

      i think the biggest niggly little gremlin i had was the original clock
      circuitry. when the first load came out of the factory, the clock
      circuit was completely screwed up, big time. after that was fixed
      everything worked fine. i must admit, the two ton transformer and
      capacitor were amusing as well. i started my company in 1976 with that
      machine, and used it exclusively for the first four or five years. now
      it's been thirty years and i'm still around. must be doing something right.

      but i digress, so back to the question at hand...

      the CCS 2200 series was a Z-80 based S-100 machine, made by a company in
      sunnyvale called California Computer Systems. they were clearly aiming
      for business grade machines and didn't make kits. it was really a nice
      little contraption, but the company is long dead, along with all the
      rest of them.

      dave



      altaircomputerclub@yahoogroups.com wrote:

      >Message 3
      > From: "Steve" alltare@...
      > Date: Fri May 12, 2006 10:51am(PDT)
      >Subject: Re: working altairs
      >
      >
      >Dave-
      >
      >It's great that you still have the Altair that you built. That's a
      >keeper. I built an 8800b from a kit, and I still have it too. I now
      >wonder how I had the patience to do it. It almost worked the first
      >time I plugged it in. My only goofs were a blob of solder in one of
      >the 100-pin sockets and one cold solder joint.
      >
      >Your CSS 2000 is an unknown one to me. Is it an 8080 machine?
      >
      >That reminds me of the Pertec PCC 2000. Does anyone in the forum
      >have one of those? It was made by MITS after the takeover, using an
      >8085 CPU, a pair of 8" internal floppies, and a "P-100" (not S-100)
      >buss. It's a pretty rare bird- not a single picture to be found by
      >Google or Yahoo.
      >
      >steve
      >
      >
      >
      >

      --
      Dave Sroelov
      A & S Computer Services, Inc.
      2813 Carriage Meadows Drive
      Wake Forest, NC 27587

      Tel: 919-554-4388
      Fax: 919-554-9431
      email: dave@...
    • Steve
      Those early Altairs had all kinds of timing problems. Thankfully, the model B referenced everthing to the system clock and most of those bugs disappeared.
      Message 2 of 11 , May 13, 2006
      • 0 Attachment

        Those early Altairs had all kinds of timing problems.  Thankfully, the model B referenced everthing to the system clock and most of those bugs disappeared.  They never did get the hang of dynamic memories, though.

        I have a few CCS boards, but have not seen a 2200 computer "in the flesh" that I can recall.  Is this the one?

        <img src="http://www.computercloset.org/ccs.jpg" height="373" width="640">
        http://www.computercloset.org/ccs.jpg 

        =======================

        --- In altaircomputerclub@yahoogroups.com, Dave Sroelov <dave@...> wrote:
        >
        > steve,
        >
        > i think the biggest niggly little gremlin i had was the original clock
        > circuitry. when the first load came out of the factory, the clock
        > circuit was completely screwed up, big time. after that was fixed
        > everything worked fine. i must admit, the two ton transformer and
        > capacitor were amusing as well. i started my company in 1976 with that
        > machine, and used it exclusively for the first four or five years. now
        > it's been thirty years and i'm still around. must be doing something right.
        >
        > but i digress, so back to the question at hand...
        >
        > the CCS 2200 series was a Z-80 based S-100 machine, made by a company in
        > sunnyvale called California Computer Systems. they were clearly aiming
        > for business grade machines and didn't make kits. it was really a nice
        > little contraption, but the company is long dead, along with all the
        > rest of them.
        >
        > dave
        >
        >
        >
        > altaircomputerclub@yahoogroups.com wrote:
        >
        > >Message 3
        > > From: "Steve" alltare@...
        > > Date: Fri May 12, 2006 10:51am(PDT)
        > >Subject: Re: working altairs
        > >
        > >
        > >Dave-
        > >
        > >It's great that you still have the Altair that you built. That's a
        > >keeper. I built an 8800b from a kit, and I still have it too. I now
        > >wonder how I had the patience to do it. It almost worked the first
        > >time I plugged it in. My only goofs were a blob of solder in one of
        > >the 100-pin sockets and one cold solder joint.
        > >
        > >Your CSS 2000 is an unknown one to me. Is it an 8080 machine?
        > >
        > >That reminds me of the Pertec PCC 2000. Does anyone in the forum
        > >have one of those? It was made by MITS after the takeover, using an
        > >8085 CPU, a pair of 8" internal floppies, and a "P-100" (not S-100)
        > >buss. It's a pretty rare bird- not a single picture to be found by
        > >Google or Yahoo.
        > >
        > >steve
        > >
        > >
        > >
        > >
        >
        > --
        > Dave Sroelov
        > A & S Computer Services, Inc.
        > 2813 Carriage Meadows Drive
        > Wake Forest, NC 27587
        >
        > Tel: 919-554-4388
        > Fax: 919-554-9431
        > email: dave@...
        >

      • Allison Parent
        ... Not on a bet, only some of the worst bugs. I have one of the earliest ones. Powersupply was too weak to support 16k of S4K ram and IO, CPU clock plain
        Message 3 of 11 , May 14, 2006
        • 0 Attachment
          --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@...> wrote:
          >
          >
          > Those early Altairs had all kinds of timing problems. Thankfully, the
          > model B referenced everthing to the system clock and most of those
          >bugs disappeared. They never did get the hang of dynamic memories,
          >though.

          Not on a bet, only some of the worst bugs. I have one of the earliest
          ones. Powersupply was too weak to support 16k of S4K ram and IO, CPU
          clock plain sucked as it relied on oneshots, bus ringing was problem
          too.

          To make it work passibly ok the backplane was replaced with a two
          sided WAMCO part with terminators, Power transformer rewound, filter
          cap values increased, CPU clock logic replaced with 8224 (Intel clock
          gen). Most of the real problems really didn't show till you have
          12-16k of ram and some IO while running BASIC.

          > I have a few CCS boards, but have not seen a 2200 computer "in the
          > flesh" that I can recall. Is this the one?

          I have a complete CCS2200. It's a nice machine and smaller than some
          but has robust powersupply. Great machine!

          > <img src="http://www.computercloset.org/ccs.jpg
          > <http://www.computercloset.org/ccs.jpg> " height="373" width="640">
          > http://www.computercloset.org/ccs.jpg
          > <http://www.computercloset.org/ccs.jpg>
          >
          > =======================
          > --- In altaircomputerclub@yahoogroups.com, Dave Sroelov <dave@>
          > wrote:
          > >
          > > steve,
          > >


          > > i think the biggest niggly little gremlin i had was the original clock
          > > circuitry. when the first load came out of the factory, the clock
          > > circuit was completely screwed up, big time. after that was fixed
          > > everything worked fine. i must admit, the two ton transformer and
          > > capacitor were amusing as well. i started my company in 1976 with that
          > > machine, and used it exclusively for the first four or five years. now
          > > it's been thirty years and i'm still around. must be doing something
          > right.
          > >
          > > but i digress, so back to the question at hand...
          > >
          > > the CCS 2200 series was a Z-80 based S-100 machine, made by a company
          > in
          > > sunnyvale called California Computer Systems. they were clearly aiming
          > > for business grade machines and didn't make kits. it was really a nice
          > > little contraption, but the company is long dead, along with all the
          > > rest of them.
          > >
          > > dave
          > >
          > >
          > >
          > > altaircomputerclub@yahoogroups.com wrote:
          > >
          > > >Message 3
          > > > From: "Steve" alltare@
          > > > Date: Fri May 12, 2006 10:51am(PDT)
          > > >Subject: Re: working altairs
          > > >
          > > >
          > > >Dave-
          > > >
          > > >It's great that you still have the Altair that you built. That's a
          > > >keeper. I built an 8800b from a kit, and I still have it too. I now
          > > >wonder how I had the patience to do it. It almost worked the first
          > > >time I plugged it in. My only goofs were a blob of solder in one of
          > > >the 100-pin sockets and one cold solder joint.
          > > >
          > > >Your CSS 2000 is an unknown one to me. Is it an 8080 machine?
          > > >
          > > >That reminds me of the Pertec PCC 2000. Does anyone in the forum
          > > >have one of those? It was made by MITS after the takeover, using an
          > > >8085 CPU, a pair of 8" internal floppies, and a "P-100" (not S-100)
          > > >buss. It's a pretty rare bird- not a single picture to be found by
          > > >Google or Yahoo.
          > > >
          > > >steve
          > > >
          > > >
          > > >
          > > >
          > >
          > > --
          > > Dave Sroelov
          > > A & S Computer Services, Inc.
          > > 2813 Carriage Meadows Drive
          > > Wake Forest, NC 27587
          > >
          > > Tel: 919-554-4388
          > > Fax: 919-554-9431
          > > email: dave@
          > >
          >
        • Steve
          Allison Parent- I have had much better luck with the 8800 than you had. I still own an original 8800 that I bought at a MITS surplus sale whien they were
          Message 4 of 11 , May 14, 2006
          • 0 Attachment
            Allison Parent-
            I have had much better luck with the 8800 than you had. I still own
            an original 8800 that I bought at a MITS surplus sale whien they were
            still in business. Other than having a beefed-up power supply, it is
            unmodified. I rented it to an accountant for a few years (back about
            1980), who used it daily. It had two or four 4K static RAMs, two 16K
            Static RAMs, floppy controllers, and a 2SI/O, and never had a serious
            hiccup.

            All of the Altairs had unterminated buses, so there was always the
            possibility of ringing. The noise and ringing were enough to bring a
            modern computer to its knees, but the Altair ran slow enough that it
            would usually just ignore the "ghost signals". Memory was the most
            susceptable to bus signal artifacts, but one trick that helped a lot
            was to put the touchiest memory cards as physically close as possible
            to the CPU board, where the bus's S/N ratio was the greatest. This
            was particularly effective with the MITS 16K dynamic boards.

            Obviously, your experience was different, but most people didn't have
            to resort to the extremes that you did, beyond correcting the power
            supply and making sure the one-shots were timed right.

            The 8800b model took your advice- The CPU board used an 8224 chip,
            and all 3 power supply voltages were robust, using a huge transformer
            and big filter caps.

            steve
            ========================

            --- In altaircomputerclub@yahoogroups.com, "Allison Parent"
            <kb1gmx@...> wrote:
            >
            > --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@> wrote:
            > >
            > >
            > > Those early Altairs had all kinds of timing problems.
            Thankfully, the
            > > model B referenced everthing to the system clock and most of those
            > >bugs disappeared. They never did get the hang of dynamic
            memories,
            > >though.
            >
            > Not on a bet, only some of the worst bugs. I have one of the
            earliest
            > ones. Powersupply was too weak to support 16k of S4K ram and IO,
            CPU
            > clock plain sucked as it relied on oneshots, bus ringing was problem
            > too.
            >
            > To make it work passibly ok the backplane was replaced with a two
            > sided WAMCO part with terminators, Power transformer rewound, filter
            > cap values increased, CPU clock logic replaced with 8224 (Intel
            clock
            > gen). Most of the real problems really didn't show till you have
            > 12-16k of ram and some IO while running BASIC.
            >
            > > I have a few CCS boards, but have not seen a 2200 computer "in the
            > > flesh" that I can recall. Is this the one?
            >
            > I have a complete CCS2200. It's a nice machine and smaller than
            some
            > but has robust powersupply. Great machine!
            >
            > > <img src="http://www.computercloset.org/ccs.jpg
            > > <http://www.computercloset.org/ccs.jpg> " height="373"
            width="640">
            > > http://www.computercloset.org/ccs.jpg
            > > <http://www.computercloset.org/ccs.jpg>
            > >
            > > =======================
            > > --- In altaircomputerclub@yahoogroups.com, Dave Sroelov <dave@>
            > > wrote:
            > > >
            > > > steve,
            > > >
            >
            >
            > > > i think the biggest niggly little gremlin i had was the
            original clock
            > > > circuitry. when the first load came out of the factory, the
            clock
            > > > circuit was completely screwed up, big time. after that was
            fixed
            > > > everything worked fine. i must admit, the two ton transformer
            and
            > > > capacitor were amusing as well. i started my company in 1976
            with that
            > > > machine, and used it exclusively for the first four or five
            years. now
            > > > it's been thirty years and i'm still around. must be doing
            something
            > > right.
            > > >
            > > > but i digress, so back to the question at hand...
            > > >
            > > > the CCS 2200 series was a Z-80 based S-100 machine, made by a
            company
            > > in
            > > > sunnyvale called California Computer Systems. they were clearly
            aiming
            > > > for business grade machines and didn't make kits. it was really
            a nice
            > > > little contraption, but the company is long dead, along with
            all the
            > > > rest of them.
            > > >
            > > > dave
            > > >
            > > >
            > > >
            > > > altaircomputerclub@yahoogroups.com wrote:
            > > >
            > > > >Message 3
            > > > > From: "Steve" alltare@
            > > > > Date: Fri May 12, 2006 10:51am(PDT)
            > > > >Subject: Re: working altairs
            > > > >
            > > > >
            > > > >Dave-
            > > > >
            > > > >It's great that you still have the Altair that you built.
            That's a
            > > > >keeper. I built an 8800b from a kit, and I still have it too.
            I now
            > > > >wonder how I had the patience to do it. It almost worked the
            first
            > > > >time I plugged it in. My only goofs were a blob of solder in
            one of
            > > > >the 100-pin sockets and one cold solder joint.
            > > > >
            > > > >Your CSS 2000 is an unknown one to me. Is it an 8080 machine?
            > > > >
            > > > >That reminds me of the Pertec PCC 2000. Does anyone in the
            forum
            > > > >have one of those? It was made by MITS after the takeover,
            using an
            > > > >8085 CPU, a pair of 8" internal floppies, and a "P-100" (not S-
            100)
            > > > >buss. It's a pretty rare bird- not a single picture to be
            found by
            > > > >Google or Yahoo.
            > > > >
            > > > >steve
            > > > >
            > > > >
            > > > >
            > > > >
            > > >
            > > > --
            > > > Dave Sroelov
            > > > A & S Computer Services, Inc.
            > > > 2813 Carriage Meadows Drive
            > > > Wake Forest, NC 27587
            > > >
            > > > Tel: 919-554-4388
            > > > Fax: 919-554-9431
            > > > email: dave@
            > > >
            > >
            >
          • Craig Landrum
            I have an original 8800 also that I built up from parts assembled in 2004-2005. The biggest problem I have is the unreliability of the diskette board pair.
            Message 5 of 11 , May 15, 2006
            • 0 Attachment
              I have an original 8800 also that I built up from
              parts assembled in 2004-2005. The biggest problem I
              have is the unreliability of the diskette board pair.
              Took me a while to get it to be able to boot, but even
              now it doesn't do so reliably, and I suspect I need to
              start replacing the caps on the disk controller board(s).
              Any ideas welcome. I believe I've found and replaced any bad
              74xx chips.

              When building the bus and power supply, I replaced
              all the electrolytics in the power supply. It is
              the original 8800 one and not the beefed up version,
              since I sort of wanted to keep it original as
              possible. I am using the original transformers and
              the original small rectifier.

              What I have plugged into my bus right now is:

              MITS CPU board
              MITS 4 16K static RAM cards
              MITS SIO2 card -drives a 9600 baud dumb terminal
              MITS SIOC? card - drives a 110 baud current loop ASR33
              MITS Two-board floppy controller with ?latest? eng. fixes
              MITS 1702 PROM board with boot prom and disk head positioner
              MITS centronics card

              I also have a MITS parallel card which I don't use and
              do not normally have plugged into the bus.

              This is 11 cards being driven off the original supply,
              but it seems to be able to supply about 8 volts to each
              card.

              The RAM check out fine with the RAM checking S/W utils
              Serial and centronics all work fine.

              Using this configuration, I have been able to boot disk
              BASIC, Altair DOS, and CP/M, and can selectively boot them
              (using the front panel switchs) so that the system "console"
              is either the fast dumb terminal or the ASR33 (I love
              being able to choose just using the boot switches) but I
              cannot boot anything until the system has been powered up for
              about 10 minutes and I've fiddled with it a bit. Then it
              suddenly seems to pass some warmup threshold and
              things start to work. The voltage does not seem to be
              a problem during that time. Caps on the disk board(s)??

              FYI, I also have one of those third-height bus terminator
              cards. Doesn't seem to make any difference whether it is
              in or out.

              Suggestions welcome.
              --
              Craig Landrum
              Chief Technical Officer
              mindwrap, inc.
              Phone: (540) 675-3015 x 229
              Fax: (540) 675-3130
              email: craigl@...
            • Andrew Kessel
              Could you guys remind me. What was the difference between the 8800 (which I have) and the 8800a? thanks
              Message 6 of 11 , May 15, 2006
              • 0 Attachment
                Could you guys remind me.  What was the difference between the 8800 (which I have) and the 8800a?
                 
                thanks

                 
              • H_E_Robert
                Craig, I can t recall ever having a temperature reactive cap issue, they tend to either work, or not. But the clock circuits and timing issues can certainly
                Message 7 of 11 , May 15, 2006
                • 0 Attachment
                  Craig,

                  I can't recall ever having a temperature reactive "cap"
                  issue, they tend to either work, or not. But the clock
                  circuits and timing issues can certainly be adversely affected
                  by temp. And of course the obvious, that IC's can develop temp
                  issues as well. The best way to isolate would be to reduce system
                  boards to the minimum, space them out on the back plane, and maybe
                  isolate the issue to the "mainframe" or the disk drive by warming
                  up the the drive first, and seeing if the Altair can boot from power
                  -up. And then reverse the process. Of course you can use a hand
                  held hair dryer to speed the warm-up process, targeting your suspected
                  board or component, or a can of that "freezing" spray to do the reverse.

                  Back in the old days, my tech's did board level repairs on all our DEC
                  VAX machines, and those techniques were used regularly. As far as caps
                  go, one thing I tend to forget is that the "tantalum" caps are
                  electrolytic's, and are adversely affected by age, and MITS tended to use
                  them in situations like timing, where the finer tolerances were required.

                  I probably didn't tell you anything you didn't already know or try, but
                  best of luck on your continuing Altair adventure!

                  Just Bob!

                  Craig Landrum wrote:
                  > I have an original 8800 also that I built up from
                  > parts assembled in 2004-2005. The biggest problem I
                  > have is the unreliability of the diskette board pair.
                  > Took me a while to get it to be able to boot, but even
                  > now it doesn't do so reliably, and I suspect I need to
                  > start replacing the caps on the disk controller board(s).
                  > Any ideas welcome. I believe I've found and replaced any bad
                  > 74xx chips.
                  >
                  > When building the bus and power supply, I replaced
                  > all the electrolytics in the power supply. It is
                  > the original 8800 one and not the beefed up version,
                  > since I sort of wanted to keep it original as
                  > possible. I am using the original transformers and
                  > the original small rectifier.
                  >
                  > What I have plugged into my bus right now is:
                  >
                  > MITS CPU board
                  > MITS 4 16K static RAM cards
                  > MITS SIO2 card -drives a 9600 baud dumb terminal
                  > MITS SIOC? card - drives a 110 baud current loop ASR33
                  > MITS Two-board floppy controller with ?latest? eng. fixes
                  > MITS 1702 PROM board with boot prom and disk head positioner
                  > MITS centronics card
                  >
                  > I also have a MITS parallel card which I don't use and
                  > do not normally have plugged into the bus.
                  >
                  > This is 11 cards being driven off the original supply,
                  > but it seems to be able to supply about 8 volts to each
                  > card.
                  >
                  > The RAM check out fine with the RAM checking S/W utils
                  > Serial and centronics all work fine.
                  >
                  > Using this configuration, I have been able to boot disk
                  > BASIC, Altair DOS, and CP/M, and can selectively boot them
                  > (using the front panel switchs) so that the system "console"
                  > is either the fast dumb terminal or the ASR33 (I love
                  > being able to choose just using the boot switches) but I
                  > cannot boot anything until the system has been powered up for
                  > about 10 minutes and I've fiddled with it a bit. Then it
                  > suddenly seems to pass some warmup threshold and
                  > things start to work. The voltage does not seem to be
                  > a problem during that time. Caps on the disk board(s)??
                  >
                  > FYI, I also have one of those third-height bus terminator
                  > cards. Doesn't seem to make any difference whether it is
                  > in or out.
                  >
                  > Suggestions welcome.
                • Craig Landrum
                  ... Thanks, Bob! All good suggestions. I should have done these tests already, but haven t. I ve also been bitten years ago by chips with a heat problem.
                  Message 8 of 11 , May 15, 2006
                  • 0 Attachment
                    >I can't recall ever having a temperature reactive "cap"
                    >issue, they tend to either work, or not. But the clock
                    >circuits and timing issues can certainly be adversely affected
                    >by temp. And of course the obvious, that IC's can develop temp
                    >issues as well. The best way to isolate would be to reduce system
                    >boards to the minimum, space them out on the back plane, and maybe
                    >isolate the issue to the "mainframe" or the disk drive by warming
                    >up the the drive first, and seeing if the Altair can boot from power
                    >-up. And then reverse the process. Of course you can use a hand
                    >held hair dryer to speed the warm-up process, targeting your suspected
                    >board or component, or a can of that "freezing" spray to do the reverse.
                    >
                    >Back in the old days, my tech's did board level repairs on all our DEC
                    >VAX machines, and those techniques were used regularly. As far as caps
                    >go, one thing I tend to forget is that the "tantalum" caps are
                    >electrolytic's, and are adversely affected by age, and MITS tended to use
                    >them in situations like timing, where the finer tolerances were required.
                    >
                    >I probably didn't tell you anything you didn't already know or try, but
                    >best of luck on your continuing Altair adventure!
                    >
                    >Just Bob!
                    >


                    Thanks, Bob! All good suggestions. I should have done these tests
                    already, but haven't. I've also been bitten years ago by chips with
                    a heat problem. I'll see what I can do with your selective power-up
                    tests before I go buy a can of cool-down stuff.
                    --
                    Craig Landrum
                    Chief Technical Officer
                    mindwrap, inc.
                    Phone: (540) 675-3015 x 229
                    Fax: (540) 675-3130
                    email: craigl@...
                  • H_E_Robert
                    Andrew, The 8800a had the 8800 front panel with 8800b components like flat handled swithces, one piece motherboard, and b power supply. Just Bob!
                    Message 9 of 11 , May 15, 2006
                    • 0 Attachment
                      Andrew,

                      The 8800a had the 8800 front panel with 8800b components like flat
                      handled swithces, one piece motherboard, and "b" power supply.

                      Just Bob!

                      Andrew Kessel wrote:
                      > Could you guys remind me. What was the difference between the 8800
                      > (which I have) and the 8800a?
                      >
                      > thanks
                      >
                      >
                      >
                      > ------------------------------------------------------------------------
                      > YAHOO! GROUPS LINKS
                      >
                      > * Visit your group "altaircomputerclub
                      > <http://groups.yahoo.com/group/altaircomputerclub>" on the web.
                      >
                      > * To unsubscribe from this group, send an email to:
                      > altaircomputerclub-unsubscribe@yahoogroups.com
                      > <mailto:altaircomputerclub-unsubscribe@yahoogroups.com?subject=Unsubscribe>
                      >
                      > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                      > Service <http://docs.yahoo.com/info/terms/>.
                      >
                      >
                      > ------------------------------------------------------------------------
                      >
                    • Steve
                      Andy- The 8800 had 4-slot mother boards, and you could daisy chain 4 of them to give you a total of 16 slots (16 S-100 sockets). The 8800A had a single
                      Message 10 of 11 , May 15, 2006
                      • 0 Attachment
                        Andy-

                        The 8800 had 4-slot mother boards, and you could daisy chain 4 of
                        them to give you a total of 16 slots (16 S-100 sockets). The 8800A
                        had a single 16-slot mother board similar to, but not the same as,
                        the one in the 8800b.

                        The 8800A could have either of two different front panels, depending
                        on when it was made- the original 8800 panel OR one that was
                        essentially the same, except that the power switch was "right side
                        up". There were some other minor variations in the screen printing.
                        And of course, the aluminum trip strip stuck to the bottom of the
                        front panel was different, too.

                        8800A's were made with the 8800-style "bat handle" toggle switches OR
                        with the 8800b-style flattened handles. Both variations were produced.

                        The 8800A used an 8800 power supply, but with bigger transformer. It
                        didn't use the 8800b supply or capacitors.

                        The 8800 and 8800A front panels were wired directly to the mother
                        board by lots of individual wires. The 8800b's front panel wasn't
                        connected directly to the mother board at all. It communicated with
                        the computer through a "Display/Control Interface Board", also known
                        as a front panel interface board. This was an S-100 board that plugs
                        into the mother board.

                        The same CPU board was used for the 8800 and 8800A. The B's CPU
                        board was completely different.

                        If you dig through the message archives, I think you'll find more
                        info on these things.

                        Steve
                        ========================================

                        --- In altaircomputerclub@yahoogroups.com, H_E_Robert <ueoguy@...>
                        wrote:
                        >
                        > Andrew,
                        >
                        > The 8800a had the 8800 front panel with 8800b components like flat
                        > handled swithces, one piece motherboard, and "b" power supply.
                        >
                        > Just Bob!
                        >
                        > Andrew Kessel wrote:
                        > > Could you guys remind me. What was the difference between the
                        8800
                        > > (which I have) and the 8800a?
                        > >
                        > > thanks
                        > >
                      • Allison Parent
                        inline comments... ... Mine was ordered December of 1974, when Poptronics het the box I was there. It was very low (xxx200) serial number. Nearly all the
                        Message 11 of 11 , May 16, 2006
                        • 0 Attachment
                          inline comments...

                          --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@...> wrote:
                          >
                          > Allison Parent-
                          > I have had much better luck with the 8800 than you had. I still own
                          > an original 8800 that I bought at a MITS surplus sale whien they were
                          > still in business. Other than having a beefed-up power supply, it is
                          > unmodified. I rented it to an accountant for a few years (back about
                          > 1980), who used it daily. It had two or four 4K static RAMs, two 16K
                          > Static RAMs, floppy controllers, and a 2SI/O, and never had a serious
                          > hiccup.

                          Mine was ordered December of 1974, when Poptronics het the box
                          I was there. It was very low (xxx200) serial number. Nearly all
                          the mods done were documeted by MITS in later days in early 1975.
                          The only one of mine that was the 8224 mod as I despise oneshots
                          for critical apps and I considered the clock critical.

                          One of the things everyone sorta knew(fould out later) was the TI
                          oneshots were better than National or Moto in the front pannel for
                          example.


                          > All of the Altairs had unterminated buses, so there was always the
                          > possibility of ringing. The noise and ringing were enough to bring a
                          > modern computer to its knees, but the Altair ran slow enough that it
                          > would usually just ignore the "ghost signals". Memory was the most
                          > susceptable to bus signal artifacts, but one trick that helped a lot
                          > was to put the touchiest memory cards as physically close as possible
                          > to the CPU board, where the bus's S/N ratio was the greatest. This
                          > was particularly effective with the MITS 16K dynamic boards.

                          They were a minor problem. The 88S4K rams were fussy until the mod
                          came out and then later the "upgrade" to 884MCD cards.

                          > Obviously, your experience was different, but most people didn't have
                          > to resort to the extremes that you did, beyond correcting the power
                          > supply and making sure the one-shots were timed right.

                          I was early adoptor and I was not alone with the problems.

                          I still have that machine and a 8800BT, both working.

                          > The 8800b model took your advice- The CPU board used an 8224 chip,
                          > and all 3 power supply voltages were robust, using a huge transformer
                          > and big filter caps.

                          The PS was a problem.

                          Allison

                          > steve
                          > ========================
                          >
                          > --- In altaircomputerclub@yahoogroups.com, "Allison Parent"
                          > <kb1gmx@> wrote:
                          > >
                          > > --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@> wrote:
                          > > >
                          > > >
                          > > > Those early Altairs had all kinds of timing problems.
                          > Thankfully, the
                          > > > model B referenced everthing to the system clock and most of those
                          > > >bugs disappeared. They never did get the hang of dynamic
                          > memories,
                          > > >though.
                          > >
                          > > Not on a bet, only some of the worst bugs. I have one of the
                          > earliest
                          > > ones. Powersupply was too weak to support 16k of S4K ram and IO,
                          > CPU
                          > > clock plain sucked as it relied on oneshots, bus ringing was problem
                          > > too.
                          > >
                          > > To make it work passibly ok the backplane was replaced with a two
                          > > sided WAMCO part with terminators, Power transformer rewound, filter
                          > > cap values increased, CPU clock logic replaced with 8224 (Intel
                          > clock
                          > > gen). Most of the real problems really didn't show till you have
                          > > 12-16k of ram and some IO while running BASIC.
                          > >
                          > > > I have a few CCS boards, but have not seen a 2200 computer "in the
                          > > > flesh" that I can recall. Is this the one?
                          > >
                          > > I have a complete CCS2200. It's a nice machine and smaller than
                          > some
                          > > but has robust powersupply. Great machine!
                          > >
                          > > > <img src="http://www.computercloset.org/ccs.jpg
                          > > > <http://www.computercloset.org/ccs.jpg> " height="373"
                          > width="640">
                          > > > http://www.computercloset.org/ccs.jpg
                          > > > <http://www.computercloset.org/ccs.jpg>
                          > > >
                          > > > =======================
                          > > > --- In altaircomputerclub@yahoogroups.com, Dave Sroelov <dave@>
                          > > > wrote:
                          > > > >
                          > > > > steve,
                          > > > >
                          > >
                          > >
                          > > > > i think the biggest niggly little gremlin i had was the
                          > original clock
                          > > > > circuitry. when the first load came out of the factory, the
                          > clock
                          > > > > circuit was completely screwed up, big time. after that was
                          > fixed
                          > > > > everything worked fine. i must admit, the two ton transformer
                          > and
                          > > > > capacitor were amusing as well. i started my company in 1976
                          > with that
                          > > > > machine, and used it exclusively for the first four or five
                          > years. now
                          > > > > it's been thirty years and i'm still around. must be doing
                          > something
                          > > > right.
                          > > > >
                          > > > > but i digress, so back to the question at hand...
                          > > > >
                          > > > > the CCS 2200 series was a Z-80 based S-100 machine, made by a
                          > company
                          > > > in
                          > > > > sunnyvale called California Computer Systems. they were clearly
                          > aiming
                          > > > > for business grade machines and didn't make kits. it was really
                          > a nice
                          > > > > little contraption, but the company is long dead, along with
                          > all the
                          > > > > rest of them.
                          > > > >
                          > > > > dave
                          > > > >
                          > > > >
                          > > > >
                          > > > > altaircomputerclub@yahoogroups.com wrote:
                          > > > >
                          > > > > >Message 3
                          > > > > > From: "Steve" alltare@
                          > > > > > Date: Fri May 12, 2006 10:51am(PDT)
                          > > > > >Subject: Re: working altairs
                          > > > > >
                          > > > > >
                          > > > > >Dave-
                          > > > > >
                          > > > > >It's great that you still have the Altair that you built.
                          > That's a
                          > > > > >keeper. I built an 8800b from a kit, and I still have it too.
                          > I now
                          > > > > >wonder how I had the patience to do it. It almost worked the
                          > first
                          > > > > >time I plugged it in. My only goofs were a blob of solder in
                          > one of
                          > > > > >the 100-pin sockets and one cold solder joint.
                          > > > > >
                          > > > > >Your CSS 2000 is an unknown one to me. Is it an 8080 machine?
                          > > > > >
                          > > > > >That reminds me of the Pertec PCC 2000. Does anyone in the
                          > forum
                          > > > > >have one of those? It was made by MITS after the takeover,
                          > using an
                          > > > > >8085 CPU, a pair of 8" internal floppies, and a "P-100" (not S-
                          > 100)
                          > > > > >buss. It's a pretty rare bird- not a single picture to be
                          > found by
                          > > > > >Google or Yahoo.
                          > > > > >
                          > > > > >steve
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > >
                          > > > > --
                          > > > > Dave Sroelov
                          > > > > A & S Computer Services, Inc.
                          > > > > 2813 Carriage Meadows Drive
                          > > > > Wake Forest, NC 27587
                          > > > >
                          > > > > Tel: 919-554-4388
                          > > > > Fax: 919-554-9431
                          > > > > email: dave@
                          > > > >
                          > > >
                          > >
                          >
                        Your message has been successfully submitted and would be delivered to recipients shortly.