Intermec 6100 Reference Guide

R

INT 1Ah, Function AH = 00h:  Read System Timer Ticks

BIOS
Retrieves the values from the BIOS data areas 40:6Eh (high word) and 40:6Ch

(low word).  The value returned is the total number of clock ticks since midnight

of system timer channel 0.  Clock ticks occur 18.2 times per second and are proĆ

cessed by INT 08h.  Interrupts are disabled while the timer tick is read to preĆ

vent update during access to the memory locations.  The timer overflow flag, reĆ

turned in AL, is reset to zero when this function is executed.
On Entry:  AH = 00h
On Return:

CX = High word of system timer tick count

DX = Low word of system timer tick count

AL = Timer overflow flag

0 if day has not rolled over since last read

1 if timer value has exceeded 24 hours

INT 1Ah, Function AH = 01h:  Set System Timer Ticks

BIOS
Sets the BIOS data values located at 40:6Ch and 40:6Eh to the data contained in

CX and DX, respectively.  It thereby sets the system timer tick count.  Execution

of this function clears the timer overflow flag at location 40:70h.
On Entry:

AH = 01h

CX = High byte of the system timer tick count

DX = Low byte of the system timer tick count

On Return:

None

INT 1Ah, Function AH = 02h:  Read the Real-Time Clock Time

BIOS
Reads the hour, minute, second, and Daylight Savings option data from the

CMOS RAM area of the MC 146818.  Must verify that the updateĆinĆprogress bit

is zero and disable interrupts before accessing the CMOS data.
On Entry:

AH =02h

On Return:

CH = Hours in BCD (0ć23)

CL = Minutes in BCD (0ć59)

DH = Seconds in BCD (0ć59)

DL = Daylight Savings Time option

0 = No Daylight Savings Time 

1 = Daylight Savings Time