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  1. 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...
  2. 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...
  3. 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...
  4. 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...
  5. 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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    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...
  10. 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...
  11. 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...
  12. 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:
    ...
  13. 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
  14. 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
  18. Thread: Sysgen

    by deramp5113
    Replies
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    1,294

    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...
  19. Thread: Sysgen

    by deramp5113
    Replies
    24
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    1,294

    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,...
  20. Thread: Sysgen

    by deramp5113
    Replies
    24
    Views
    1,294

    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...
  21. Thread: Sysgen

    by deramp5113
    Replies
    24
    Views
    1,294

    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...
  22. Thread: Sysgen

    by deramp5113
    Replies
    24
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    1,294

    SYSGEN version 2 supports an image file specified...

    SYSGEN version 2 supports an image file specified on the command line. Here's a link to the original source for SYSGEN 2 from Digital Research
    ...
  23. First, make sure the Z80 reset line (pin 26) goes...

    First, make sure the Z80 reset line (pin 26) goes low and then high when you press and then release the reset button. It looks like your board has been strapped to use the standard PRESET line from...
  24. From what I can see looking at the jumpers on...

    From what I can see looking at the jumpers on your PROM/RAM card and the CPU board, the system is configured as a very standard VG system. During the first three bus cycles after power on or reset,...
  25. What about the 5v regulator on the PROM/RAM...

    What about the 5v regulator on the PROM/RAM (upper right corner)?

    Mike
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