9 May
2009
9 May
'09
8:24 a.m.
dwight elvey wrote:
The reason for the FM on the fist track was that it
was then compatable with boot code for disk that
were all FM. One could boot FM and then switch to
MFM for the rest of the disk. It seems strange now
but made sense at the time.
Dwight
True, but that's not all. The reason for FM on T0 is so that any disk
of any format that had been properly sysgen'd and contained the proper
CBIOS could then be booted from that system. It allowed the flexibility
of having a multi-format system. Another reason is so that the disk
controller boot rom (or boot code wherever it was) could start booting
ANY disk since they all began with FM 26x128. Boot in FM, read the boot
loader. THEN, the boot loader which could be more complex and would
specifically match that individual floppy (unlike the boot rom), it
would continue the boot, handling whatever format the rest of the disk was.
jS