I was thumbing through a document called the HP Touchscreen Personal Computer Systems Configuration Guide and noticed that it had some handy information.
This sets the ROM version as D.
This means that it should cope with the later operating system. It shipped with 45621-13001 A.01.03, but it seems to run with E.01.01 ie MS-DOS 3.2.
It also supports the 9122 disk drive unit, which i’ve used on the HPDrive emulator. It’s also much the same as the 9123 unit that i’ve added. Although it claims compatibility, i’ve had no success accessing double-sided disk images. Under MS-DOS 2.1 i can’t format single sided disks in the 9123, but i can under MS-DOS 3.2.
