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Service technician diagnostics disk for QNX 2 machine?

For the old QNX2 and QNX4 RTOS

Service technician diagnostics disk for QNX 2 machine?

Postby obsol33t » Tue Dec 05, 2017 10:50 pm

I have an old CEMCORP/UNISYS Lexicon server from the mid-late 1980s that was used to run a network of ICON terminals in a school. It boots the "ICON Series System Software 3.00.04" which is based on QNX 2.05b. It seems to be working well.

I've imaged all of the floppy disks that came with it as well as the MFM hard drive. I have installation disks for the ICON Series SSW versions 3 and 4. I want to use version 4 so that I can install some newer applications, and bought a second MFM drive to install it on. It is a Seagate ST-4096 80 MB drive.

A former student assistant network administrator of these Lexicon servers remembers a teacher calling in a service technician to work on it one day. He had a special service technician diagnostics disk that could do things like low level format a drive, and maybe even change the drive geometry settings. This former student recently imaged the ROM chips and disassembled the code. He discovered that it is hard coded to use 17 sectors/track and 4 heads, so only the number of cylinders can be increased to a maximum of 1023 which means it can only use up to 33 MB. The WD1002-05 controller doesn't seem to have a BIOS that I can enter on boot to configure anything.

I'm hoping that someone here might be familiar with mid-late 1980's computers running QNX 2, and might know what this mysterious service technician disk may have been. It would be even better if someone has an image of such a disk! I've tried booting an MSDOS boot disk on the machine and it won't boot. I suspect it might only support booting a QNX 2 filesystem.

Any help would be greatly appreciated.
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