INT 1A,0 - Read System Clock Counter

AH = 00

on return:

AL = midnight flag, 1 if 24 hours passed since reset

CX = high order word of tick count

DX = low order word of tick count

- incremented approximately 18.206 times per second

- at midnight CX:DX is zero

- this function can be called in a program to assure the date is

updated after midnight; this will avoid the passing two midnights

date problem