INT 1Ah,  00h (0)        Read System-Timer Time Counter                   all

Reports the current time of day, and whether 24 hours has passed since
1) the last power-on, 2) the last system reset, or 3) the last system-
timer time read or set.

On entry:      AH         00h

Returns:       CX         High-order part of clock count
DX         Low-order part of clock count
AL         0 if 24 hours has not passed; else 1

                                                                          

Notes:         The following formulas convert the clock count to
the time of day:

Hour      = Clock / 65543 (1007h)
Remainder = Clock MOD 65543

Minutes   = Remainder / 1092 (444h)
Remainder = Remainder MOD 1092

Second    = Remainder / 18.21
Remainder = Remainder MOD 18.21

Hundredths = CINT(Remainder * 100)

The "system timer" (as distinguished from the real-
time clock) is the timer that's set when the system
is started. This time is temporary, lasting only as
long as the system is turned on.

The clock count may also be read as a 4-byte integer
at memory location 0:046C. This 4-byte value is
equal to the 4-byte integer in CX:DX after Service
00h has been called.

After the call, the flag (at 0:0470h) stating
whether 24 hours has passed or not, is cleared.

When TIME is typed at the command line, DOS gets the
time by means of this service.

Counts occur at the rate of 18.2 per second.

See also: INT 1Ah, 01h
See also: INT 1Ah, 02h

INT 1Ah, 00h (0) Read System-Timer Time Counter all