HP110+ upgrade DOS2.11 to DOS6

[Sylvain Cote]

In the x86 BIOS pre-standardization world, all computers had a custom BIOS and manufacturer had to write their own IO.SYS file.
This is why MS-DOS is delivered with IO.SYS (computer-specific) and MSDOS.SYS (generic).
While this was somewhat easy for text mode, graphic mode was another thing. (CGA, EGA, VGA, HGC, HP-150, DEC Rainbow PC-100, etc.)