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    XMS memory problem.

    Hi all, I've been designing a 16 bit XMS board for use on AT class motherboards that have limited onboard expansion. For example I have a Commodore PC-40-III that can only have 1MB onboard. The board currently consists of between 2 and 8 AS6C4008-55PCN 512K x 8 bit SRAMs (one each for the high...
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    Adding a reset button to a 5170?

    Hi all, Anyone know of a convenient way of adding a reset button to the 8MHz version of the 5170 motherboard? Cheers. Phill.
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    Sprinter III Schematic.

    Hi all, Does anyone have the schematic for the Holmes Sprinter III, the documentation refers to a schematic but it's not included in the PDF file. Cheers. Phill.
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    Tandon TM-100-2A problem.

    Hi all, I have an IBM branded TM-100-2A 40 track DS drive that I'd like to repair. Last time it was used it suffered a mildly catostrophic failure (c36 a 475, which if I'm reading correctly is 4.75µf, tant capacitor went pop and caught fire!). I can source and replace this cap easily enough but...
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    Model 3, making a bootable floppy.

    Hi all, I have a model 3 with a FreHD, which can boot LDOS 5.3.1 or Newdos. I can format a floppy disk from both but is there an easy way of transfering the system to them so that they are bootable on a mchine without a FreHD (or with the HD disconnected). Cheers. Phill.
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    TRSDOS / LSDOS for the Model III disassembily / source

    Hi all, Does anyone know if there is an archive of the source / a dissasembily of either TRSDOS or LSDOS for the TRS80 Model 3 available anywhere? I've searched and come up with nothing. Cheers. Phill.
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    Model 3 video output.

    Hi all, I have a working TRS80 model 3 motherboard, but that's all I have :( I'm using a PS2->Crosspoint switch to implement the keyboard, and have a circuit using a 74LS02 and some discretes to combine the syncs and video into a composite sync like signal. However when I feed this into one...
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    Model 3/Model 4 floppy drive interface.

    Hi all, I keep seeiing refferences to the later versions of the Model 4 using a 177x based floppy controller (e.g. Wikipedia), but cannot find a schematic for this. Does anyone know if it is available and if so where? Cheers. Phill.
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    PET power transformer.

    Hi all, I have one of the Universal PET boards with the 6845 video controller, that I'd like to power up. I have tested the board in my PET 3008 and it seems to work without problems. However I only have one PET case :( So does anyone have the specs of the mains transformer please, or advice...
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    XTIDE universal bios disk translation....

    Hi all, Following on from my post about imaging.... Is there documented anywhere an explanation of the translation scheme used by the XTIDE universal bios ? Also is there a way of enquiring of the drive e.g. via an INT call to find out what scheme is currently in use? Cheers. Phill.
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    Imaging XT-IDE CF card to use in emulation.....

    Hi all, So here's the setup I have a 5150 PC with a WD MFM controller in it, attached to this is a 20MB hard disk. This all works fine but I wanted to take a dump of the hard disk for backup / emulation purposes. The machine is running PC-DOS 4. So I installed an XT CF lite rev 2, jumpered so...
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    UMB Memory tester..

    Hi all, Is there a program that will test memory above 640K on a PC / XT class machine. Specifically I want to test memory in defined UMB areas. e.g. the 128K D000-EFFF Cheers. Phill.
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    Correct seetings for latest XTIDE and lo-tech CF-lite.v2

    Hi all, I'm trying to update the firmware on my Lo-tech CF-LITE v2 to the lates XTIDE firmware. I've tried using both the IDE-XT and IDE-XTL, but obviously edited the settings to be XT-CF v2/v3/Lite in PIO mode base address 0x300 (which my card is jumpered for). Saved the bios, combined it...
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    PC I/O woes.....

    Hi all, I finally think I've got to the bottom of the problems I was having with interfacing a DS12887 with the PC-RETRO board. The PC-RETRO is a chip for chip copy of the 64K-256K 5150 board and so therefore has all it's problems / limitations, namely incomplete address decoding of the I/O...
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    ISA interfacing.

    Hi all, Am I correct in assuming that only *ONE* of the the memory or I/O write strobes may be active at one time e.g. nMEMR, nMEMW, nIOR, nIOW ? The reason I ask is because I have a RAM / Clock card (I have been developing on and off for a couple of years), this has an 74ALS245 buffer between...
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    XTIDECFG saving ROM

    Hi there, In the XTIDE config / flasher program I can configure the settings of the XTIDE bios. I have done this however I don't see a way of saving the bios image back to a file so that I can later program it with a different flasher utility (lo-tech's flash in this case). Anyone know if it...
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    Clock not running....

    Hi all, I've been upgrading / restoring a Compaq Portable II (8MHz 80286) that I have been given. Because it hadn't been run for about 20 years I had to replace the CMOS battery with a new one. It takes a 3.6V AA size battery which I was able to source from Amazon. However even with the new...
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    DOS software that uses the scroll wheel.....

    Hi All, I'm developing a little adapter board that is basically a PS/2 mouse to serial mouse protocol converter. I have it working well as a standard 2 button 2 axis mouse, and is identified by the standard MS mouse driver. I'm now working on making it optionally identify as an MS scroll...
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    Everex EV-178

    Hi all, Attached is the software for the Everex EV-178 ISA memory expansion card. The files where recovered off the driver disk supplied with my cards. I'm putting this here so that people can find it....as I couldn't when I searched earlier.....feel free to archive elsewhere. Cheers. Phill.
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    Prodos and fixed disks....

    Hi there, I have been having a play round with a design for an SD card interface to the Apple that is accessable in prodos, details here : http://www.applefritter.com/?q=content/building-my-own-sd-card-interface-apple-ii I was having problems getting it working till I happened to try it with a...