The Cheater Clock

[Grevle]

I made my own clock on for the Atari and provide the executable and the Assembly listing. I name it the cheater clock because all it does is look at the rtclock adress 20 ($14) and advance the Counter one second up til 99 minutes and 59 Seconds. It adjust timing for PAL and NTSC machines. It seem to be fairly accurate , but not exactly real time clock..

 

Cheaterclock.XEX

 

The Listing in Assembler:

 

; Cheater clock

*=12288 ; set adress for program

SDMCTL = 559 ; Can turn on and off Antic (needed when creating display list)
SDLSTL = 560 ; Shadow display list pointer low - Antic må vite hvor den nye display listen er
SDLSTH = 561 ; Shadow display list pointer high 

     
 ; Here is some equates

SECONDS = 1600
TENSEC =   1601
MINUTES = 1602
TENMIN  = 1603 

     
     
     LDX #1 
     STX TENMIN ; set 1 here or the ten minute number get out of sync

     LDA #0
     
     
     STA SDMCTL ;TURN ANTIC OFF
     LDA #0 ; LOW BYTE
     STA SDLSTL ; store low byte of display list adress
     LDA #144 ; HIGHBYTE
     STA SDLSTH ;store high byte of display list adress
     LDA #34
     STA SDMCTL ; ... Turn on Antic again

    

    ; set some colors
     
     LDX #12
     STX 710
     LDX #24
     STX 708
     LDX #34
      STX 709
     LDX #58
     STX 711
     LDX #60
     STX 712
     
     ;put the clock on screen before it starts
     
     LDX #16
     STX 40220
     STX 40219
     STX 40217
     STX 40216
     LDX #26     
     STX 40218
    
START
     LDX 53268 ; check for pal atari
     CPX #1
     BEQ PAL
     LDX 20
     CPX #60  ;check rtclock to advance time 1 second ntsc
     BCC START
     JMP NTSC
PAL     
     LDX 20
     CPX #50  ; check rtclok to advance time 1 second pal
     BCC START
NTSC
     
     LDX #0
     STX 20          ;reset rtclock when wanted number is reached
     LDX TENSEC ;check if tenseconds is = 5 to advance minute counter
     CPX #5
     BEQ CHTENSEC     
CONT
     
     LDX SECONDS
     CPX #10
     BEQ TENSEC2
     LDA SECONDS
     CLC
     ADC #16
     STA 40220
     INC SECONDS
     JMP START

TENSEC2
     LDA TENSEC
     ADC #16
     STA 40219
     INC TENSEC
     LDX #1
     STX SECONDS
     LDX #16
     STX 40220
     
     JMP START

CHTENSEC
     LDX SECONDS ; check if seconds = 9 to advance minute counter
     CPX #10
     BEQ SETZ     
     JMP CONT

     
MINUTE2
     LDA MINUTES
     ADC #16
     STA 40217
     INC MINUTES
     LDX #0
     STX TENSEC
     JMP CONT

SETZ
     LDX MINUTES
     CPX #9
     BEQ MINUTEC
CONTR
     LDX #1 ;reset seconds counter
     STX SECONDS
     LDX #0 ; SLOPPY CODE ADJUSTMENT
     STX TENSEC
     LDX #16
     STX 40220 ; put zeroes on screen
     STX 40219
     INC MINUTES
     CLC
     LDA MINUTES
     ADC #16
     STA 40217 ; put minutes on screen
     
     JMP START
MINUTEC
     LDX #16
     STX 40217
     INC TENMIN
     CLC
     LDA TENMIN
     ADC #15
     STA 40216 ; put tenminutes on screen
     LDX #0
     STX MINUTES
     DEC MINUTES ; decrease one for sloppy coding
     JMP CONTR

; The Display list for GR.0
*=36864
Mylist

.Byte 112,112,112 ; three blank lines
.byte 66,64,156 ; first is lms command two other is for screen adress (Adress off display list) high byte,lowbyte  = low byte,highbyte = 39936
.byte 2,2,2,2,2,2,2,2,2,2,2,2
.byte 2,2,2,2,2,2,2,2,2,2,2 ; 23 times antic mode 2 lines = Basic mode 0
.byte 65,144,0 ; first is jump on vertical blank instructions,2 other is the adress low byte first. the adress for the display list itself

 

 

Edited March 9, 2020 by Grevle