10 Oct
2006
10 Oct
'06
5:42 p.m.
On 10/10/2006 at 4:29 PM Chris M wrote:
Even the 5150 had ancillary sockets, but I wasn't
simply referring to adding BASIC roms to a board. What
the big deal could have been I don't know, but some at
least felt they were getting a little extra something
by having the original IBM code on board. Yes there
must have been some kind of difference, albeit small.
One of the benefits was that code was in a standard location and RAM
locations used by BIOS had a known assignment. There were early programs
that simply used far CALLs to invoke bits and pieces of BIOS ROM routines.
For many years, Phoenix tried to keep routine entry points the same as IBM
in their BIOSes. Writing a BIOS that was "functionally" equivalent often
wasn't good enough.
Cheers,
Chuck