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  1. Those switches have not been made for quite a...

    Those switches have not been made for quite a while now. A stash was found unexpectedly a couple of years ago and member glitch bought them up for the community. Contact him to see what he still has....
  2. The last ones trickled out of here at about one...

    The last ones trickled out of here at about one nameplate per year, so it seems most of the pent up demand has been met. I’d have to see how small of a batch they’d be willing to run.

    Mike
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    Waking up this old thread... In playing with a...

    Waking up this old thread... In playing with a SWTPC 6800 computer I just restored, I learned something about the automatic reader and punch on my Teletype that I never knew.

    As background, the...
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    If you can't find the actual SWTBUG ROM, you'll...

    If you can't find the actual SWTBUG ROM, you'll probably have to use an EPROM adapter to program a standard EPROM yourself. Unfortunately, the pinout and chip selects of the MC6830 are very different...
  5. I have typed in the assembly source for couple of...

    I have typed in the assembly source for couple of the missing utilities I was looking for (there are a few listings in the LFD-400 manual), so I now have a pretty complete and useful Percom disk...
  6. I’ve been able to complete the system running...

    I’ve been able to complete the system running under the MiniDisk+ PROMs and added several programs like BASIC and an assembler to the disk. It all works together, but operations don’t integrate with...
  7. Great - I'd like to see what PROMs you have...

    Great - I'd like to see what PROMs you have installed. For console I/O functions, the Percom PROMs call entry points in the computer's PROM monitor, so it shouldn't be hard to patch your PROMs to use...
  8. SWTPC 6800 and Percom Floppy Controller

    Iím restoring a SWTPC 6800 that includes the Percom LFD-400 floppy controller. This controller goes on the SS-50 bus instead of the SS-30 bus where the SWTPC controllers installed. The standard...
  9. Corey, Information about board mods and wiring...

    Corey,

    Information about board mods and wiring are here: https://deramp.com/downloads/misc_hardware/paper_tape_readers/OP-80A/

    Yes, I have more of the adapter boards. Send me your address by...
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    4,674

    On the original 8800, the data LEDs are driven...

    On the original 8800, the data LEDs are driven directly from the data-in bus. Each bit of the data-in bus is pulled up to 5v on the Altair CPU board, so if no memory or I/O board is driving the...
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    Great! I suspected IC-S over IC-U because the...

    Great!

    I suspected IC-S over IC-U because the pin 11 output of IC-U (which drives the lower 8 address switches), and the pin 13 input to the same gate on IC-U had to be working since deposits...
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    Good progress! Examine is actually not flakey at...

    Good progress! Examine is actually not flakey at all (doesnít work right, but not flakey). In your 2nd video, the CPU is not at the M1 state (M1 light on) when you raise examine, so a bad examine is...
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    You’re closer than you think. D7 doesn’t not...

    You’re closer than you think. D7 doesn’t not appear to be burnt out. Instead, you have actually deposited 43h at location zero, not C3h, which is why the loop doesn’t work when single stepping. This...
  14. Sounds like a good plan. For short programs, I’ve...

    Sounds like a good plan. For short programs, I’ve found that 200ms of delay after CR gives reliable loads. For larger programs, 300ms is necessary. Not easy to reliably translate that into a number...
  15. Loading of BASIC is full 8-bit, so I’m not sure...

    Loading of BASIC is full 8-bit, so I’m not sure what your ADM will do with the 8-bit characters and possible unintended escape sequences it sees. I don’t recall how “dumb” the 3A is. Maybe dumb...
  16. If you have a PROM card installed, you can use 4K...

    If you have a PROM card installed, you can use 4K BASIC and a load/save PROM. See BLOAD.ASM here:
    ...
  17. 1140 : DB 06 " " in 006H 1142 : E6 01 " ...

    1140 : DB 06 " " in 006H
    1142 : E6 01 " " ani 001H
    1144 : C2 40 11 " @ " jnz L1140
    1147 : DB 07 " " in 007H
    1149 : C9 " " ret
  18. 4K BASIC does not have CLOAD or CSAVE commands....

    4K BASIC does not have CLOAD or CSAVE commands. In 8K BASIC 4.0, cassette input loop is at 1140h. The output loop is at 114Eh.

    Mike
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    Dave, I know the original two-piece covers...

    Dave,

    I know the original two-piece covers were made in both steel and aluminum during the Sol-20's production run, but I am not familiar with a factory made one piece cover.

    Speaking of...
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    Polymorphic Poly-8813 Owners

    Looking for a favor from Poly-8813 owners. Take a look at your CPU board, video board, and RAM boards and see if any of them have a wire as part of a mod that is tacked onto bus pin 16. The CPU board...
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    That byte is unused. I’ve seen both 00h and FAh...

    That byte is unused. I’ve seen both 00h and FAh in SOLOS ROMs.

    Mike
  22. Thread: Sysgen

    by deramp5113
    Replies
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    1,355

    Yes, you relocate CP/M down to allocate space at...

    Yes, you relocate CP/M down to allocate space at a known address within the uninitialized area of the BIOS. Then write a standard CP/M program (e.g., IOBYTE.COM) that copies a payload of code into...
  23. Thread: Sysgen

    by deramp5113
    Replies
    24
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    1,355

    I recently solved a similar issue in which I...

    I recently solved a similar issue in which I needed to add full IOBYTE support to an existing BIOS, but there was no way the additional code would fit in the two existing boot tracks. Unfortunately,...
  24. Thread: Sysgen

    by deramp5113
    Replies
    24
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    1,355

    The typical BIOS development process is to run...

    The typical BIOS development process is to run MOVCPM and save the result to a file like you did (e.g., CPM62.COM). Then run "DDT CPM62.COM" and patch your own CP/M loader in at 900h. The start of...
  25. Thread: Sysgen

    by deramp5113
    Replies
    24
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    1,355

    In the SYSGEN 2 source, most likely you can get...

    In the SYSGEN 2 source, most likely you can get it working by simply changing the NSECTS and NTRKS equates to match your system. Only in a few cases have I had to further customize SYSGEN than those...
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