markz@microsoft.UUCP (Mark Zbikowski) (11/04/83)
A quote from a recent issue of Info-IBMPC
"... [Am I missing something? IBM uses interrupts in
the range 0-1F and Intel reserves these. This seems
like a problem to me. -Ed.]..."
Yes, something is being missed, but the problem seen is
only a problem for IBM and for the ISV's who happened to
use the direct calls to the IBM ROM BIOS rather than use
the DOS interface. The much-publicized issue was NOT whether
or not IBM had used the interrupt vectors but rather that
MSDOS/PC-DOS had usurped them. To quote from the previous
article in Info-IBMPC:
"... Page 2-4 of the I'M manual reveals that MS-DOS
uses 25 of those 27 reserved interrupt vectors.
Specifically, MS-DOS uses 5 and 8 through 31
inclusive...."
This is not the case. The cited documentation says NOTHING
about MSDOS/PC-DOS using these vectors. Rather, on the
previous two pages, the document describes these interrupts
as the interface to the IBM ROM BIOS.
On page 2-7, under the heading of 'other R/W memory ussage'
are described the ONLY vectors in use by MSDOS/PC-DOS.
FYI: MSDOS/PC-DOS has been running on several 80188's and
80186's for quite some time without modification. Only the
device drivers were changed.
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