HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                             INT 8 - System timer

       no input data

       related memory:

       40:6C = Daily timer counter (4 bytes)
       40:70 = 24 hr overflow flag (1 byte)
       40:67 = Day counter on all products after AT
       40:40 = Motor shutoff counter - decremented until 0 then
               shuts off diskette motor

       - INT 1C is invoked as a user interrupt
       - the byte at 40:70 is a flag that certain DOS functions use
         and adjust the date if necessary.  Since this is a flag and
         not a counter it results in DOS (not the RTC) losing days
         when several midnights pass before a DOS call
       - generated 18.2 times per second by the 8253 Programmable Interval
         Timer (PIT)
       - normal INT 8 execution takes approximately 100 microseconds

       - see   8253

Esc or Alt-X to exit int 8 Home/PgUp/PgDn/End ←↑↓→
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