Robert Fortune wrote in a message to All:
 RF>   Does anyone know why a doubleword (40:6C thru 40:6F) is reserved
 RF> in the   BIOS Data Area to hold the system timer ticks (18.2xxxx
 RF> per second), but   only uses 3 of the 4 bytes to hold the number of
 RF> timer ticks? I've   written test programs to verify this and all my
 RF> tests show that 40:6F   is never used, and is always zero. Any and
 RF> all replies welcome. TIA! 
Because it contains the number of timer ticks since midnight. The normal 
timer tick rate is 18.2 ticks per second, so that would give 1572480 ticks 
per day. For the fourth, most significant byte to actually be used, the tick 
value would have to reach a value of 16777216, which would take over 10 days, 
and the timer ticks are reset at midnight.
The fourth byte *would* be used on a system that uses about 200 ticks per 
second or more for its timer tick rate.
Even if the fourth byte would never be used under normal circumstances, it is 
still required because 3 bytes is not a type the CPU can handle without 
special conversions.
greetings,
Tom
tomtorfs@village.uunet.be
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