• Please review our updated Terms and Rules here

Search results

  1. S

    ZFx86™ 486 PC-in-a-Chip

    Benchmarking a retro machine and comparing with similar machines tells you whether your machine is configured and working properly. In my opinion, this is useful information. There is little point in playing retro games on a retro machine in a worse way than they were intended for.
  2. S

    How can I write DOS Floppies from .img files in DOS 6.22?

    I've written a program which receives raw image files via serial (xmodem) and writes them to floppy disk. Does not access any hardware directly. May be useful if the system used to write the images lacks storage for the image files, and works on non-compatible machines. I wrote it to write disk...
  3. S

    Bit7 in CP/M characters.

    CP/M itself only uses 7-bit ASCII characters. Some implementations use the top bit as a parity bit, extended characters or strip/ignore it. Others used it as a single-character video attribute. Depending on your terminal hardware, this could be inverse, underlined, bright, bold or blinking. The...
  4. S

    PC/IX Images

    I would like to have the manuals as well. The disks are, if I remember correctly, in "dump" format and you use "restore" to install them.
  5. S

    Sound Card / Serial Port Conflict

    Do an optical check of the mainboard. Look for battery damage, rust, or capacitor leakage (electrolyic fluid on the surface). If moving cards between ISA slots changes the symptoms, you may have a (partial) short circuit somewhere. Also check the connectors. Remove everything from the board...
  6. S

    Sound Card / Serial Port Conflict

    Which means that it is probably not the sound card itself, but something else. You seem to have many cards installed, maybe your bus load is too high; it is possible that a capacitor or some other component is starting to leak current, overloading the bus. Also, a failing PSU producing unstable...
  7. S

    Sound Card / Serial Port Conflict

    You could have a bus conflict, for example caused by some decoder chip going bad and randomly (or less randomly) activating some other chip. I also had seriously weird behaviour on a 386/486-ish board which turned out to be a broken crystal. The oscillator circuitry produced ISA frequencies all...
  8. S

    Ctrl-C vs Ctrl-Break

    At a hardware level (on an AT or newer), the BREAK key is quite special. It does not follow the make/break (down/up) convention, and needs to be handled specially in the state machine if you want to detect it. It is not possible to detect when the key is released either. So not strictly a...
  9. S

    C code portability question

    When I was looking at getting the Arachne web browser working in Linux again, I noticed that there is no universal 32-bit type available for both 16 and 64 bit compiles: "int" is either 16 or 32 bit, and "long" is either 32 or 64 bit. (For Arachne specifically, this causes font rendering to...
  10. S

    WinNT 3.1 - 4.0 software for ALPHA / MIPS / PPC architectures

    WinWorldPC also contains some Internet Explorer versions for MIPS and Alpha.
  11. S

    Really cheap CP/M

    PCjs has added support for the 8080, see https://www.pcjs.org/machines/pcx80/exerciser/. Another 8080 CP/M machine is available at https://www.tramm.li/i8080/emu8080.html. A Z80-based implementation is at https://heathkit.garlanger.com/emulator/jsH89/, but I couldn't get it to boot. A version...
  12. S

    Really cheap CP/M

    Hi, Congratulations. I made a similar thing last year, but simpler and using an Atmega8515 (because of XMEM). Pictures and sources are available at https://www.mikrocontroller.net/topic/523119. CPU speed is decent (approximately 2.6 MHz i80, at 16 MHz), disk speed is acceptable. The Atmega8515...
  13. S

    Any interest in a standalone controller for QIC-02 interface drives?

    Cool. What hardware/controller are you using?
  14. S

    Classic repair issue

    Some mild handwashing soap only, and yes.
  15. S

    Classic repair issue

    I had cleaned the area under and around the caps with alcohol and a toothbrush, but not the rest of the board. Did some (a lot) more scrubbing on the board, which changed the checkerboard pattern to a garbage screen with a fully corrupted Sad Mac. Then I did even more scrubbing, which turned it...
  16. S

    Classic repair issue

    About 40 mV on 5V and 60 mA on 12 V, measured on the hard drive power connector (without floppy/hard drive connected). Looks good to me. Hmm, I don't have access to an ultrasonic cleaner... used ethanol and a careful application of toothbrush, nothing else. So you're saying that a deep cleaning...
  17. S

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

    Native IDE interfaces generally support CHS without issues (Linux definitely does), but even if it is not supported (e.g. through USB interfaces), you should be able to at least detect the drive and show name and serial number. ddrescue is open source: https://www.gnu.org/software/ddrescue/ I...
  18. S

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

    You definitely want to use a somewhat more modern system, Linux and dd_rescue (not plain dd). That program has been designed to extract the absolute maximum possible off a failing hard drive. It will outperform whatever you can cobble together yourself, and it will likely do a lot better than...
  19. S

    Classic repair issue

    I've completely recapped the analog board, except for the two big 220 µF / 400 V caps. Not sure whether they are prone to leaking, but all other caps in the whole system have been replaced with fresh ones now. Unfortunately, the system still displays a checkerboard pattern and I don't know much...