IBM PC CONVERTIBLE Technical Reference page 186

01E5
01E5 B4 OA
01E7 BO 26
01E9 E8 0000
OIEC B4 OB
OlEE BO 82
OIFO
E8 0000
DIF3 B4 OC
01F5 E8 0000
01F8 B4 00
OIFA E8 0000
OlFD C3
OIFE
01FE
01FE 51
01FF B9 0258
0202
0202 B4 OA
0204 E8 0000
0207 A8 80
0209
74 05
020B E2 F5
0200 33 CO
020F F9
0210
0210 59
0211 C3
0212
0212
INITIALIZE_STATUS
FUNCTION: INITIALIZE RTC CONTROL AND STATUS REGISTERS
REG A = 976.6 USEC PERIODIC INTERRUPT
32.768 KHZ TIME BASE
REG B = ENABLE SET, 24HR, BCD MODES
DISABLE ALL INTERRUPTS AND DAYLIGHT SAVINGS
READ REG C AND D TO CLEAR STATUS
INPUT: NONE
OUTPUT: NONE
REGISTERS MODIFIED: AX
INITIALIZE_STATUS PROC
MOV AH, RTCUP _STAT
MOV AL, 26H
CALL PULRTCNMI
NEAR
ADDRESS AND INITIALIZE
; RTCUP_STAT (RegA) TO GIVE
; **INT.=976.6 MICRO SEC.
MOV AH,RTCMODE ; ADDRESS AND INITIALIZE
MOV AL,SELCLOCK+SEL24HR ; RTCMODE (RegB): (=82H)
CALL PULRTCNMI * MODES ON ... SET, 24HR, BCD
MOV
CALL
MOV
CALL
RET
AH,RTCINLSTAT
GELRTCNMI
AH,RTCCOND_STAT
GELRTCNMI
INITIALIZLSTATUS ENDP
UPD_IN_PR
* DSABLE ALL OTH (NO DYLGHT)
GET RTCINLSTAT (RegC)
TO INITIALIZE IT
GET RTCCOND_STAT (RegD)
TO INITIALIZE IT
RETURN TO CALLER
FUNCTION: WAIT FOR RTC CLOCK TO UPDATE TIME. SET CARRY IF CLK NOT
OPERATING (DOESN'T LEAVE UPDATE MODE AFTER 600 MSEC).
INPUT: NONE
OUTPUT: AX = 0 CLOCK NOT UPDATING
CARRY FLAG = 1 CLOCK NOT OPERATING
= 0 CLOCK HAS BEEN UPDATED
REGISTERS MODIFIED: AX
UPD_IN_PR PROC NEAR
PUSH CX SAVE CX
MOV CX ,600 SET LOOP COUNT
UPDATE :
MOV
AH,RTCUP _STAT
ADDRESS AND
CALL GELRTCNMI
GET RTCUP _STAT (RegA)
TEST AL,RTCUIP
IF NOT UPDATING (UIP=O)
JZ
UPD_I N_PREND
THEN RETURN
LOOP UPDATE ELSE IF CX
<>
0 THEN LOOP
XOR AX,AX ELSE CLEAR AX AND
STC SET CARRY FOR ERROR SIGNAL
UPD_IN_PREND:
POP CX RESTORE CX
RET RETURN TO CALLER
UPD_IN_PR
ENDP
TOD_PROC
ENDP
SUBTTL SET TIME OF DAY
ROM BIOS 2-161