* COPYRIGHT (C) 1984 BY PETER A. STARK

* 146818 CLOCK PATCH FOR SK*DOS 

* PROGRAM READS THE DATE FROM THE PT-69 BOARD'S CLOCK
* CHIP ON BOOTUP OF SK*DOS, SO USER DOES NOT HAVE TO
* TYPE IT IN.

* PROGRAM DOES NOTHING IF THE CLOCK IS NOT SET PROPERLY

* APPEND THIS CODE TO SK*DOS.SYS

*  EQUATES

MONTH   EQU    $CC0E     MONTH
DAY     EQU    $CC0F     DAY
YEAR    EQU    $CC10     YEAR
COLDS   EQU    $CD00     SK*DOS TRANSFER ADDRESS
CLOCKA  EQU    $E01D
CLOCKD  EQU    $E01E

* PATCH SK*DOS TO COME HERE
        ORG    $CA02
        JMP    GETDAT    GO TO THIS PATCH TO GET DATE

* GET THE TIME AND DATE AND CHECK THEM

        ORG    $C400
GETDAT  PSHS   A,B,X,Y,U SAVE ALL REGISTERS
        LDA    #2
        BSR    READIT    GET MINUTES
        CMPA   #$59      CHECK IT
        BHI    NOGOOD    CLOCK NOT SET IF >59 MIN
        LDA    #4
        BSR    READIT    GET HOURS
        ANDA   #$7F      REMOVE AM/PM FLAG
        CMPA   #$12      CHECK IT
        BHI    NOGOOD    NG IF PAST 12 O'CLOCK
        LDA    #6
        BSR    READIT    GET DAY OF WEEK
        CMPA   #7        CHECK IT
        BHI    NOGOOD    NO 8-DAY WEEKS ALLOWED
        LDA    #7
        BSR    READIT    GET DAY OF MONTH
        CMPA   #$31      CHECK IT
        BHI    NOGOOD    MAX 31 DAYS A MONTH
        BSR    BCDHEX    CONVERT BCD TO HEX
        STA    DAY       GIVE IT TO SK*DOS
        LDA    #8
        BSR    READIT    GET MONTH
        CMPA   #$12      CHECK IT
        BHI    NOGOOD    MAX 12 MONTHS A YEAR
        BSR    BCDHEX    CONVERT BCD TO HEX
        STA    MONTH     GIVE IT DO SK*DOS

        LDA    #9
        BSR    READIT    GET THE YEAR
        CMPA   #$84      CHECK IT
        BLO    NOGOOD    MUST BE 84 OR LATER
        CMPA   #$99
        BHI    NOGOOD    ASSUME THIS CENTURY
        BSR    BCDHEX    CONVERT BCD TO HEX
        STA    YEAR      GIVE IT TO SK*DOS
        PULS   A,B,X,Y,U
        RTS              AND THEN CONTINUE SK*DOS

* ON INVALID TIME, JUST RETURN TO SK*DOS

NOGOOD  PULS   A,B,X,Y,U
        JMP    $CA05     CONTINUE JUST AFTER EXIT

* GET DATA FROM 146818 CLOCK CHIP

READIT  STA    CLOCKA    GIVE ADDRESS TO CLOCK
        LDA    CLOCKD    GET THE DATAGAIN
        RTS

* CONVERT BCD TO HEX ROUTINE

BCDHEX  PSHS   A         SAVE BCD NUMBER
        LSRA
        LSRA             MOVE MSD INTO LSD
        LSRA
        LSRA
        LDB    #10
        MUL              MULTIPLY IT BY 10
        PULS   A         GET OLD VALUE FROM STACK
        ANDA   #$0F      KEEP ONLY LSD
        PSHS   B         SAVE TENS VALUE ON STACK
        ADDA   0,S+      ADD IT TO UNITS
        RTS              AND RETURN

        END    COLDS