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mod10-bin-dec.s
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mod10-bin-dec.s
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ORB = $6000
ORA = $6001
DDRB = $6002
DDRA = $6003
val = $0200
mod10 = $0202
msg = $0204
E = $10
RW = $20
RS = $40
.org $8000
reset:
LDX #$ff ;set pointer
TXS
LDA #$ff ;set VIA as autput
STA DDRB
JSR lcd_init
LDA #$28 ;4bit-2lines
JSR lcd_instruction
LDA #$0F ; Display on, cursor on, blinking on
JSR lcd_instruction
LDA #$06 ; Increment,shift
JSR lcd_instruction
LDA #$01 ;clear Display
JSR lcd_instruction
LDA #0
TAX
TAY
STA msg
LDA number
STA val
LDA number + 1
STA val + 1
divide:
LDA #0
STA mod10
STA mod10 + 1
CLC
LDX #16
div_loop:
ROL val
ROL val + 1
ROL mod10
ROL mod10 + 1
SEC
LDA mod10
SBC #10
TAY
LDA mod10 + 1
SBC #0
BCC ignore_r
STY mod10
STA mod10 + 1
ignore_r:
DEX
BNE div_loop
ROL val
ROL val + 1
LDA mod10
CLC
ADC #"0"
STA mod10
LDA mod10
JSR push_char
LDA val
ORA val + 1
BNE divide
LDX #0
print:
LDA msg,x
BEQ loop
JSR write_char
INX
JMP print
push_char:
PHA
LDY #0
loop_char:
LDA msg,y
TAX
PLA
STA msg,y
INY
TXA
PHA
BNE loop_char
PLA
STA msg,y
RTS
loop:
JMP loop
number: .word 1729
lcd_wait:
PHA ;save A
LDA #$F0 ;set VIA as in/out
STA DDRB
lcd_busy:
LDA #RW
STA ORB
LDA #(RW | E)
STA ORB
LDA ORB ;upper nibble
PHA
LDA #RW
STA ORB
LDA #(RW | E)
STA ORB
LDA ORB
PLA
AND #$08
BNE lcd_busy
LDA #RW ;Clear E bit
STA ORB
LDA #$FF ;set VIA as output
STA DDRB
PLA
RTS
lcd_instruction:
JSR lcd_wait
PHA
LSR
LSR
LSR
LSR
STA ORB ; set upper nibble
ORA #E
STA ORB
EOR #E
STA ORB
PLA
AND #$0F
STA ORB
ORA #E
STA ORB
EOR #E
STA ORB
RTS
lcd_init:
LDA #$02 ;4bit mode
STA ORB
ORA #E
STA ORB
AND #$0F
STA ORB
RTS
write_char:
JSR lcd_wait
PHA
LSR
LSR
LSR
LSR
ORA #RS
STA ORB ; set upper nibble
ORA #E
STA ORB
EOR #E
STA ORB
PLA
AND #$0F
ORA #RS
STA ORB
ORA #E
STA ORB
EOR #E
STA ORB
RTS
.org $9ffc ;for 28c64 rom
.word reset
.word $0000
.org $fffc
.word reset
.word $0000