USQB015@LIVERPOOL.AC.UK (Mark Powell) (05/08/89)
According to the Hitch-hikers guide to the BIOS (?) X/BIOS calls are
re-entrant to a "few" levels. However, I wouldn't try it as from past
experience I find that re-entrant is synonamous with non-re-entrant. Also
using the same BIOS call in the foreground as well as in the interrupt
is a recipe for disaster. I doubt very many BIOS calls could handle that
sort of "abuse". The print routine is sure to use some fixed memory locations
while it's printing, which would be corrupted by the call to the same routine
in the timer a code. Also BIOS calls have quite an overhead when talking
in terms of interrupt handlers. It's better to write your own routines for
such work. Maybe....
Mark Powell
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