INT 1aH: Timer I/O (and MRCI POST Hook)
INT 1aH services provide access to the system clock. Also INT 1aH may be
intercepted by a hardware-based MRCI compression system.
b001H Query MRCI hardware support
AH BIOS Service Supported by
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00H read the clock (ticks) [PC] [XT] [AT]
01H set the clock (ticks) [PC] [XT] [AT]
02H read time from CMOS RTC [AT]
03H set the time on CMOS RTC [AT]
04H read date from CMOS RTC [AT]
05H set the date on CMOS RTC [AT]
06H set alarm on CMOS RTC [AT]
07H cancel alarm on CMOS RTC [AT]
The PC BIOS works with a "tick count" of the number of 55ms intervals
which have occurred since the PC was turned on or reset. The AT BIOS also
provides access to the real-time clock values which are updated constantly
without CPU action, and are stored in the AT's CMOS Memory.
On AT-compatible machines, most short-interval timer/alarm operations are
perfomed via INT 15H.
See Also: ROM-BIOS Functions
System Information Functions (DOS fns)
BIOS Data Area (0040:006c)