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  1. J

    Olivetti PCS86 ram expansion info

    Fascinating. It's a pity that there doesn't seem to be documentation for the FE2011 chipset online, bar a 2-page overview.
  2. J

    Identifying a 'buffer' space at the end of a program

    By way of contrast, SID starts the program being debugged with SP=0100h, so unless the program sets up its own stack there's a chance of it being overwritten by (for example) DMA to 80h.
  3. J

    Amstrad PC1512 Hard Disk

    There is no FDISK for GEM. GEM runs on top of DOS (or DOS Plus), and the FDISK on the PC1512 boot disk is the one for MSDOS 3.2. FDISK /MBR was introduced in MSDOS 5, so won't be available on the PC1512 unless you use a more recent version of MSDOS. Not quite. There is the possibility of a...
  4. J

    sanyo mbc 550 michtron copy protection removal help

    I had another look at the protection code, and searching for the sequence B2 02 B9 03 00 80 F2 03 and replacing the first two bytes by EB 13 should bypass it. But the resulting EXE still didn't seem to work on MAME - the problem may be some other part of the emulation rather than the copy...
  5. J

    FreeDOS or MS-DOS Low Level Disk Access (byte/block)

    Note that ddrescue and dd_rescue both exist. Of the two, I've only used ddrescue so can't say how they compare, but it seemed to do a good job with the failing hard drives I unleashed it on.
  6. J

    How can I use a 5.25 floppy on a modern computer? I need urgent help.

    I think you're going to confuse people by using terms like "ATA". That refers to a type of hard drive connection with 40 or 80 wires in the cable, not a floppy connection with 34. (Also, the PC1512 dates from 1986 and ran MSDOS 3.2, and its display is not anything like MCGA, but that's by the...
  7. J

    Combo Floppy and Hard disc controller

    The Future Domain TMC-870, TMC-875 and TMC-885 are 8-bit SCSI+floppy boards.
  8. J

    Dumped a bunch of random BIOS chips from old ISA/PCI cards/mobos- Need advice

    The 12x18 font is also found in the Windows 1.x driver for the IM1024 (V1DSK.ZIP at http://cd.textfiles.com/carousel/030A/ ).
  9. J

    Dumped a bunch of random BIOS chips from old ISA/PCI cards/mobos- Need advice

    Thanks very much. Looks as if it's 80x86 code, which is helpful if I want to point a disassembler at it. I've also attached dumps of the two fonts I found:
  10. J

    Dumped a bunch of random BIOS chips from old ISA/PCI cards/mobos- Need advice

    Having just got round to looking at these: Which dump(s) come from the Image Manager 1024?
  11. J

    Most common emulation for CP/M programs?

    It's quite possible that your .bashrc or equivalent file is directly setting the prompt to include VT100 control codes. For example, my .bashrc contains the lines: if [ "$color_prompt" = yes ]; then...
  12. J

    Most common emulation for CP/M programs?

    The MYZ80 emulator supports two families of terminal emulation: "MYZ80" - supports codes for VT100, Televideo 912, ADM 3A, Morrow MT70 "VT52" - supports codes for VT52, Amstrad CPC / PCW / Spectrum +3 It has a number of other emulations which are slight variants of the "MYZ80" scheme, with...
  13. J

    Finished most of my CP/M compatible OS outline today. :) Looking for suggestions.

    I wrote a GOTO for CP/M 3 SUBMIT back in the day, so you could actually do branching. SUBTSEA.COM at http://www.seasip.info/Cpm/software/gencpm.html contains it. The CP/M 3 SUBMIT RSX has a call to return the address of the FCB it's using for the submit file, so GOTO requests that and then seeks...
  14. J

    CP/M article on The Register

    The issue was that the 2001 licence granted permission only to distribute "the CP/M technology" as part of the "Unofficial CP/M Web Site", so no-one else could legally distribute it. The 2022 licence removes that limitation and gives everybody the right to "use, distribute, modify, enhance, and...
  15. J

    24 pin dot matrix impact printers popularity back in the day.

    In the world of Amstrad's word processors, a 24-pin printer was the most common upgrade path from the built-in 9-pin or daisywheel printer in the late 1980s/early 1990s. I remember seeing a query in one of the magazines about whether anyone had made an updated GSX driver to support the writer's...
  16. J

    Finished most of my CP/M compatible OS outline today. :) Looking for suggestions.

    CP/M 2 SUBMIT parses the .SUB file and writes a temporary file called $$$.SUB with one line per record, in reverse order. The CCP checks for this file, loads the last record into memory, shortens the file by one record, and executes the command. By default SUBMIT.COM writes $$$.SUB either to the...
  17. J

    Program load not 0100h best practive

    The Amstrad PCW uses the NMI for floppy interrupts, but it ensures that while the NMI is enabled, the memory banking has the BIOS (rather than the TPA) paged in at address 0000h. ZCN is a CP/M workalike for the Amstrad notepad computers which has to support their use of the NMI - I think it...
  18. J

    Reviving an IBM CGA Card

    It was quite common for AT motherboards (starting with the 5170 itself) to have one or two 8-bit slots, for this reason.
  19. J

    Question about CP/M Behavior on serial writes (to disk)

    On this point: Digital Research's LINK does this rather than use the random access API, presumably so it can do random access on CP/M 1.
  20. J

    Main use of large format dot matrix printers.

    At one time HM Revenue and Customs came out with a range of preprinted P45 forms (used when an employee leaves). The form comes in four parts (one for HMRC, one for the old employer, one for the new employer, and one for the employee). Two of the forms were reasonably standard: tractor-fed A4...