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MINIX and memory on the AT

With my new AboveBoard/AT (bought from the very friendly Thomas at digitaldinos.com) my AT is happily running MINIX 2.0.4.

MINIX/86 uses XMS (extended memory), not EMS (expanded memory, the scheme that pages the RAM in and out of the 640-1024k area, invented for XTs which couldn't address any higher). I understand that MINIX 1.5 had drivers for cards like the RamPage which provide hardware EMS, but those drivers have been removed. Just about any 16-bit ISA card made for the AT will provide XMS, since its "new" enlarged address bus can address up to 16 megabytes, making trickery like EMS unnecessary.


Exploring The AT

The AT came with a bootable "Exploring" disk. This plays you songs, shows a millipede eating your floppies that you forgot to back up, tells you how to work fanfold paper, teaches you the peculiar original meaning of "Cut"/"Paste", shows you how to write simple BASIC programs, and lots of other things. It's very funny today, but probably helped a lot of people not be scared of their first computer.

This file is an image of the floppy labeled "Hardware Reference Library - Exploring The IBM Personal Computer AT - Version 1.00 - Copyright International Business Machines Corp. 1983, 1984"


Intel AboveBoard/AT

This ZIP file contains all files from the floppy labeled "Intel ABOVE BOARD/AT - Installation and Utility Software - Version 2.2 - ©1985, Intel Corporation. ... Part no. 300042." The included configuration utilites don't seem to work unless they're on the A: floppy, believe it or not.

This board allowed up to 2 MB (!) of XMS in the AT.


Setup and Diagnostics

I've noticed people on the net have asked for a copy of the diagnostics/setup floppy. This allows you to set the drive types, memory size, and other things that you could set on the XT by flipping reliable-but-unfriendly DIP switches. I have a surprising amount of this original IBM stuff so as I need it, I'll try to post images. I hope IBM doesn't yell at me for it, but come on, this stuff is over 20 years old. If you lose this floppy, the AT turns into a doorstop if the BIOS battery dies.

Here are two versions of the AT's setup floppy. I also have version 1.00 dated 1984. Let me know if you need it.

This file is an image of the floppy labeled "Hardware Reference Library - Diagnostics for IBM Personal Computer AT - Version 1.02 - Copyright IBM Corp. 1981, 1982, 1983, 1984"

This file is an image of the floppy labeled "Hardware Reference Library - Diagnostics for IBM Personal Computer AT - Version 2.00 - Copyright IBM Corp. 1981, 1982, 1983, 1984, 1985"


About disk images

My AT has a "modern" 1.44 Meg 3.5 inch drive as the primary floppy. In order to make the original 360k floppy images boot from that disk, I've done this (in Linux):

  • Close or tape over both holes on a 3.5" floppy
  • fdformat /dev/fd0D720
  • dd if=the-image-file of=/dev/fd0D720

William Tooker was kind enough to write and report that he was able to make a setup floppy for his AT from my disk image, using his Windows system. He says:

I recently received an AT and needed a start disk, so I found your site, got the v2 image and used WinImage (www.winimage.com). Apparently, I was able to format a 1600KB 5&1/4" floppy to 1200KB and then write the 360KB image to the disk. It works fine and my AT boots normally again, especially now that it has a new battery. Thanks for the images.

Thanks William for this pointer.


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