Another disk imaging project

[Tony Duell]

> I understand that the jump from the PC/1981 to XT/1983
> made it possible to boot from a HD, otherwise a floppy
> had to be involved.

I am pretty sure some later PC BIOSes (not XT ones, specifically) allowed 
booting from a hard disk.

More exactly, what was added was the search for extension ROMs. No IBM PC 
or XT motherboard BIOS knew anything about hard disks. But the later ones 
searched for extension ROMs before booting, and if any were found, a 
routine in each extension ROM was executed. This routine could re-direct 
software interrupt vectors to point to routines in the ROM, in 
particular, the bootstrap vector could point to a routine in an extension 
ROM that would attempt to boot from a hard disk before falling back to 
the standard floopy drive boot routine.

-tony