12 Jun
2014
12 Jun
'14
11:36 p.m.
I'm told that some vendors shipped CP/M systems that would auto-detect
between several disk formats, e.g., 8-inch single density vs double
density, but I've never used one. Obviously the BIOS would change the
values in the disk parameter block. At what point is it safe for the BIOS
to do that? Obviously you wouldn't want to do format detection every time
the BIOS SELDSK function is called, but is it reasonable to do it whenever
READ or WRITER are called after a SELDSK of a changed drive number? Or is
there a way the BIOS can figure out specifically when the BDOS is trying to
log in a new disk?