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680b Project Update

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  • billdeg
    Here are my latest 680b restoration project notes. 1) Steve Shepard sent me an ACIA monitor prom which seems to be working. I toggled through the first 26 or
    Message 1 of 6 , Mar 1, 2007
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      Here are my latest 680b restoration project notes.

      1) Steve Shepard sent me an ACIA monitor prom which seems to be
      working. I toggled through the first 26 or so address bits and the
      data matched the prom code. No monitor dot prompt however. Checked
      using two terminals and hyperterminal/laptop.

      2) Also with help from Steve Shepard, learned that the IC in position
      L, 74L123 is missing. I located the position in the schematic to
      match/confirm. Steve suggested that I review every chip and
      connection to be sure nothing else is missing/incorrect. I am in the
      process of doing this now. I assumed that the missing IC was supposed
      to be that way, my mistake!

      3) I have taken hi-res photos to aid in the analysis. I have posted
      the new pics at the *bottom* of this page, if anyone is interested. I
      also have a link to some of the manuals.
      www.vintagecomputer.net/MITS/680/pictures.html

      4) I checked my chips on hand, I do not have a spare 74L123. If
      anyone here has one for sale, please let me know. I found a site that
      may be able to help, but I have not called them.
      http://www.mel.wisc.edu/mel_sale.htm

      Summary - Given (A big assumption) that all of the soldering is OK, I
      hope that installing a 74L123 in IC L will get me to a dot prompt
      finally. You can see from the pictures that this is definitely a kit,
      and that some connections were changed at some point.


      That's all..off to work!
      Bill D
    • Steve
      Bill, Attachments such as your picture(s) are sent to members who have chosen to read these messages via email. However, they don t stick to the messages
      Message 2 of 6 , Mar 1, 2007
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        Bill,

        Attachments such as your picture(s) are sent to members who have
        chosen to read these messages via email. However, they don't "stick"
        to the messages that are archived and read online, unless you jump
        through some hoops when posting. As a result, we online readers
        won't see your images.

        It's easier to park your pictures somewhere else and provide us with
        a link. If you don't have your own website for picture storage, I
        have found that Image Shack ( http://imageshack.us/ ) does a good job
        for free. Just store your pix there (up to 1.5MB/picture), then give
        us the URLs for them.

        MITS used a lot of those one-shot ICs. If you have the 8800 floppy
        disk controller boards (8" or 5") or an 8800 or 8800a front panel,
        you'll find several there. If you don't mind cannibalizing them, that
        is.

        Steve
        ============================
        --- In altaircomputerclub@yahoogroups.com, "billdeg" <billdeg@...>
        wrote:
        >
        > Here are my latest 680b restoration project notes.
        >
        > 1) Steve Shepard sent me an ACIA monitor prom which seems to be
        > working. I toggled through the first 26 or so address bits and the
        > data matched the prom code. No monitor dot prompt however.
        Checked
        > using two terminals and hyperterminal/laptop.
        >
        > 2) Also with help from Steve Shepard, learned that the IC in
        position
        > L, 74L123 is missing. I located the position in the schematic to
        > match/confirm. Steve suggested that I review every chip and
        > connection to be sure nothing else is missing/incorrect. I am in
        the
        > process of doing this now. I assumed that the missing IC was
        supposed
        > to be that way, my mistake!
        >
        > 3) I have taken hi-res photos to aid in the analysis. I have
        posted
        > the new pics at the *bottom* of this page, if anyone is
        interested. I
        > also have a link to some of the manuals.
        > www.vintagecomputer.net/MITS/680/pictures.html
        >
        > 4) I checked my chips on hand, I do not have a spare 74L123. If
        > anyone here has one for sale, please let me know. I found a site
        that
        > may be able to help, but I have not called them.
        > http://www.mel.wisc.edu/mel_sale.htm
        >
        > Summary - Given (A big assumption) that all of the soldering is OK,
        I
        > hope that installing a 74L123 in IC L will get me to a dot prompt
        > finally. You can see from the pictures that this is definitely a
        kit,
        > and that some connections were changed at some point.
        >
        >
        > That's all..off to work!
        > Bill D
        >
      • Bob Rosenbloom
        Anchor electronics, 408 727 3693 has 74L123 s for $1.25. Bob ... ... I hope that installing a 74L123 in IC L will get
        Message 3 of 6 , Mar 2, 2007
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          Anchor electronics, 408 727 3693 has 74L123's for $1.25.

          Bob

          > 4) I checked my chips on hand, I do not have a spare 74L123. If
          > anyone here has one for sale, please let me know. I found a site that
          > may be able to help, but I have not called them.
          > http://www.mel.wisc.edu/mel_sale.htm
          <http://www.mel.wisc.edu/mel_sale.htm>
          >
          > Summary - Given (A big assumption) that all of the soldering is OK,
          I > hope that installing a 74L123 in IC L will get me to a dot prompt
          > finally. You can see from the pictures that this is definitely a
          kit, > and that some connections were changed at some point.
          >
          >
          > That's all..off to work!
          > Bill D
        • Steve
          You can buy a 74HC123a CMOS equivalent of the 74L123 almost anywhere (Mouser, Digikey, ...). It should be pin- and function-compatable, although you might
          Message 4 of 6 , Mar 2, 2007
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            You can buy a 74HC123a CMOS equivalent of the 74L123 almost anywhere
            (Mouser, Digikey, ...). It should be pin- and function-compatable,
            although you might have to tweak the timing resistors- see the data
            sheets about that.

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

            --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@...>
            wrote:
            >
            > Bill,
            >
            > Attachments such as your picture(s) are sent to members who have
            > chosen to read these messages via email. However, they
            don't "stick"
            > to the messages that are archived and read online, unless you jump
            > through some hoops when posting. As a result, we online readers
            > won't see your images.
            >
            > It's easier to park your pictures somewhere else and provide us
            with
            > a link. If you don't have your own website for picture storage, I
            > have found that Image Shack ( http://imageshack.us/ ) does a good
            job
            > for free. Just store your pix there (up to 1.5MB/picture), then
            give
            > us the URLs for them.
            >
            > MITS used a lot of those one-shot ICs. If you have the 8800 floppy
            > disk controller boards (8" or 5") or an 8800 or 8800a front panel,
            > you'll find several there. If you don't mind cannibalizing them,
            that
            > is.
            >
            > Steve
            > ============================
            > --- In altaircomputerclub@yahoogroups.com, "billdeg" <billdeg@>
            > wrote:
            > >
            > > Here are my latest 680b restoration project notes.
            > >
            > > 1) Steve Shepard sent me an ACIA monitor prom which seems to be
            > > working. I toggled through the first 26 or so address bits and
            the
            > > data matched the prom code. No monitor dot prompt however.
            > Checked
            > > using two terminals and hyperterminal/laptop.
            > >
            > > 2) Also with help from Steve Shepard, learned that the IC in
            > position
            > > L, 74L123 is missing. I located the position in the schematic to
            > > match/confirm. Steve suggested that I review every chip and
            > > connection to be sure nothing else is missing/incorrect. I am in
            > the
            > > process of doing this now. I assumed that the missing IC was
            > supposed
            > > to be that way, my mistake!
            > >
            > > 3) I have taken hi-res photos to aid in the analysis. I have
            > posted
            > > the new pics at the *bottom* of this page, if anyone is
            > interested. I
            > > also have a link to some of the manuals.
            > > www.vintagecomputer.net/MITS/680/pictures.html
            > >
            > > 4) I checked my chips on hand, I do not have a spare 74L123. If
            > > anyone here has one for sale, please let me know. I found a site
            > that
            > > may be able to help, but I have not called them.
            > > http://www.mel.wisc.edu/mel_sale.htm
            > >
            > > Summary - Given (A big assumption) that all of the soldering is
            OK,
            > I
            > > hope that installing a 74L123 in IC L will get me to a dot prompt
            > > finally. You can see from the pictures that this is definitely a
            > kit,
            > > and that some connections were changed at some point.
            > >
            > >
            > > That's all..off to work!
            > > Bill D
            > >
            >
          • Dave Freeman
            we have 74L123 chip on our site acpsurplus.com we started this site recently to sell vintage parts as we have been getting demand for some of the weird stuff
            Message 5 of 6 , Mar 2, 2007
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              we have 74L123 chip on our site
              acpsurplus.com
              we started this site recently to sell vintage parts as we have been getting demand for
              some of the weird stuff we have accumulated over the past 30 years at ACP!
              dave freeman 714-558-8822
              On Mar 2, 2007, at 8:27 AM, Bob Rosenbloom wrote:

              Anchor electronics, 408 727 3693 has 74L123's for $1.25.

              Bob

              > 4) I checked my chips on hand, I do not have a spare 74L123. If
              > anyone here has one for sale, please let me know. I found a site that
              > may be able to help, but I have not called them.
              > http://www.mel.wisc.edu/mel_sale.htm
              <http://www.mel.wisc.edu/mel_sale.htm>
              >
              > Summary - Given (A big assumption) that all of the soldering is OK,
              I > hope that installing a 74L123 in IC L will get me to a dot prompt
              > finally. You can see from the pictures that this is definitely a
              kit, > and that some connections were changed at some point.
              >
              >
              > That's all..off to work!
              > Bill D


            • Derek J. Lassen
              I have been buying stuff from Dave s store since the 70 s.... No sh**, you need it, Dave s probably got it... (s) Derek (Altair s/n 0000067)
              Message 6 of 6 , Mar 2, 2007
              • 0 Attachment
                I have been buying stuff from Dave's store since the 70's....
                No sh**, you need it, Dave's probably got it...

                (s) Derek (Altair s/n 0000067)

                At 11:33 AM 3/2/2007, you wrote:

                >we have 74L123 chip on our site
                >acpsurplus.com
                >we started this site recently to sell vintage parts as we have been
                >getting demand for
                >some of the weird stuff we have accumulated over the past 30 years at ACP!
                >dave freeman 714-558-8822
                >On Mar 2, 2007, at 8:27 AM, Bob Rosenbloom wrote:
                >
                >>Anchor electronics, 408 727 3693 has 74L123's for $1.25.
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