User`s manual

DIGITAL-LOGIC AG MSLB-P5 Manual V0.3
PRELIMINARY 194
16.6.18 Interrupt 1Ah–Time of Day Services
The INT 1Ah software interrupt handles the time of day I/O services. A Carry flag set on exit may indi-
cate the clock is not operating.
Interrupt 1Ah Time-of-Day Services
AH = 00h Read current time
Exit:
CX High word of tick count
DX Low word of tick count
AL 00h = Day rollover has not occurred
(Timer count is less than 24 hours since last
power on or reset)
AH = 01h Set current time (Clear rollover bit)
Entry:
CX High word of tick count
DX Low word of tick count
AH = 02h Read real time clock
Exit:
CH BCD hours
CL BCD minutes
DH BCD seconds
DL 00 = Standard Time
01h = Daylight Savings
AH = 03h Set the real time clock
Entry:
CH BCD hours
CL BCD minutes
DH BCD seconds
DL 01h = Daylight saving
00h = Otherwise
AH = 04h Read date from real time clock
Exit:
CH BCD century
CL BCD year
DH BCD month
DL BCD date
AH = 05h Set date in real time clock
Entry:
CH BCD century
CL BCD year
DH BCD month
DL BCD date
AH = 06h Set real-time alarm
Entry:
CH BCD hours to alarm
CL BCD minutes to alarm
DH BCD seconds to alarm
Exit:
C 1 = Alarm already set
AH = 07h Reset real-time alarm
Exit:
AL Value written to CMOS RAM register 0Bh