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From: hamby@uahcs1.UUCP (Jason N. Hamby)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Use DOS interrupt 1C (timer tick) from MSC help needed
Message-ID: <700@uahcs1.UUCP>
Date: Sat, 5-Sep-87 00:37:07 EDT
Article-I.D.: uahcs1.700
Posted: Sat Sep  5 00:37:07 1987
Date-Received: Sun, 6-Sep-87 21:08:20 EDT
References: <338@gsg.UUCP>
Lines: 15
Keywords: MS-DOS timer interrupt MSC clock
Summary: Bug Report


Hello,
  If the driver at 1C is replaced by your own, the last thing YOUR code
  should do is to REENABLE Interrupts (STI) and then call the old interrupt
  handler. If the old interrupt handler is not called, the system crashes
  as soon as control is returned back to command.com after running your
  program. Also, an interrupt driver of that type MUST be disabled before 
  your program exits (or load your driver as a TSR) or your interrupt driver
  will not remain in memory... but the system will keep calling... CRASH.
			Jason Hamby

P.S. The above information was not conveinently located correctly in many
   texts I have at my disposal. As with most pc tech stuff, the school of
   hard knocks provided an answer. If any of this information is incorrect,
   someone please post a rebuttal. Flames will be mv \dev\null...