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From: scott@bbxsda.UUCP (Scott Amspoker)
Newsgroups: comp.lang.c
Subject: Turbo C question
Message-ID: <246@bbxsda.UUCP>
Date: 12 Oct 89 22:22:23 GMT
Distribution: na
Organization: BASIS International, Albuquerque NM
Lines: 26

I have a stange question about Turbo C.

I am doing a realtime MIDI application (using Turbo C) with an
interval timer interrupting about once a millisecond.  I noticed 
while doing an experiment one evening that fewer "ticks" were taking 
place over the period of about a minute than expected.  After considerable
investigation I determined that the less output I did to the screen,
the more accurate my counter.  If I did no output at all, the timer
was accurate down to the tick.  I concluded that something in the
putch() call in Turbo C was causing me to miss an occasional interrupt.
I figured this would happen if they had disabled the interrupts for
longer than one of my timer intervals.

Does this make sense?  The machine I am using is a Yamaha C1 which is
*extremely* compatible with a 286-based PC.  However, its LCD display
looks like a CGA to the software.  Is it possible putch() is waiting
for the horizontal retrace with the interrupts disabled?  This is not
necessary as it was with older CGA's.

Thanks

-- 
Scott Amspoker
Basis International, Albuquerque, NM
(505) 345-5232
unmvax.cs.unm.edu!bbx!bbxsda!scott