Getting the IBM PC/AT to Recognize a 1.44MB Hard Disk

Lots of time this week getting my IBM PC/AT up to speed. Here's a synopsis:

Getting a New Compact Flash Hard Drive

Instead of the XT-IDE Compact Flash hard disk adapter, I switched it for a modern XT-IDE Rev 4 IDE controller card and an IDE to Compact Flash adapter. This way I can use a spinning IDE adapter or whatever later and use the old adapter in an XT machine. Much fiddling with jumpers and it worked. Same shenanigans getting it to be bootable. My latest trick is boot to DOS 3.1 then upgrade to DOS 5. That seems to work well. I now have a 128MB Compact Flash SSD working in the AT.

Getting the Sony 1.44MB 3.5 inch disk drive working

Even though my machine is the latest revision of the PC/AT made, with a BIOS dated 11/15/1985, the IBM Diagnostics Diskette (version 2.03) setup only has 360k, 1.2M and 720k floppy drive options. The BIOS does have code for 1.44M 3.5" drives. But how to set that? I went back to minuszerodegrees.net here and there is a third party program called GSETUP.EXE that can set the right drive type. Yay!

I just needed it on my Compact Flash hard drive. To do so, I used my Tweener Pentium III/500 to read the file off a thumb drive then write it to the Compact Flash card via a USB to Compact Flash card adapter. Yes, this is a lot of hardware for this type of work. I could have copied it to the Compact Flash from my modern desktop but I'm not that smart. It did allow me to copy GSETUP to my MS-DOS 5 boot floppy - likely why I chose that route.

With GSETUP.EXE, I ran it (no special boot required and indeed I could chose 1.44MB 3.5" drive as a choice for drive B. Then I could read and write high density 3.5" drives like I should. Yay!

See the next installment for upgrading DOS & more.