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From: Bob.Stout@p6.f506.n106.z1.fidonet.org (Bob Stout)
Newsgroups: comp.lang.c
Subject: Turbo C Interrupt Question
Message-ID: <2729.2714B1DE@urchin.fidonet.org>
Date: 10 Oct 90 12:59:13 GMT
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The minute you do a geninterupt(8), you screw up your machine's time. Although 
AT and higher class PC's include a battery backed real-time clock, the only 
time it's used is when the machine's booted and its time is loaded into DOS. 
Thereafter, DOS time (i.e. the TIME command, all file time/date stamps, etc.) 
are based on the time as maintained by Int 8. Start throwing in spurious 
interrupts (bad idea anyway since Int 8 is a hardware interrupt) and you mess 
up all sorts of things. Int 1Ch is provided for just this purpose -  a 
software interrupt triggered off the Int 8 hardware interrupt. Generating 
asynchronous Int 8's means your system will also have to figure out why your 
Int 8 handler is sending out spurious EOI commands to the timer chip when it 
hasn't previously signalled an interrupt to the CPU via the interrupt 
controller chip.