Int 1AH [AT] [PS/2] Function 00H Get tick count

Returns the contents of the clock tick counter.

Call with:

AH = 00H

Returns:

AL = rolled-over flag

00H if midnight not passed since last read

<>00H if midnight was passed since last read

CX:DX = tick count (high 16 bits in CX)

Notes:

This function is supported by the PC/XT and PCjr ROM BIOS, but is not present in the ROM BIOS for the original PC.

The returned value is the cumulative number of clock ticks since midnight. There are 18.2 clock ticks per second. When the counter reaches 1,573,040, it is cleared to zero, and the rolled-over flag is set.

The rolled-over flag is cleared by this function call, so the flag will only be returned nonzero once per day.

Int 1AH Function 01H can be used to set the clock tick counter to an arbitrary 32-bit value.