p47a.asm

SEI        ;Disable interrupts
NOP
NOP
LDA #7F
STA DC0D   ;Mask CIA1's interrupt generator
SEI

LDA #08    ;Set the KERNAL's interrupt vector
STA 0315   ;at $0314/$0315
LDA #B0    ;to $08B0.
STA 0314   ;Implemented below.

LDA #00    
STA D011   ;Turn off the display
STA D020   ;Set border color to black

JSR 0855   ;Call routine to move data

LDA #3B    ;Turn the VIC's display back on
STA D011
CLI        ;Enable interrupts

0831:
LDA #00    
BNE 0831   ;Enter a tight infinite loop.

SEI        ;Disable interrupts
JSR FDA3   ;Initialise SID, CIA and IRQ
JSR FD15   ;Restore default I/O vectors
JSR E5A0   ;Initialize the VIC

LDA #01    ;Use color code "white"
LDX #00

0843:
STA D800,X  ;Fill color memory with "white"
STA D900,X
STA DA00,X
STA DB00,X
DEX
BNE 0843

CLI        ;Enable interrupts
RTS        ;Return to BASIC


;----[ Move Data, Configure VIC and CIAs ]----

0855:
LDX #00

0857:
LDA 8328,X  ;Copy color data to color memory
STA D800,X
LDA 8428,X
STA D900,X
LDA 8528,X
STA DA00,X
LDA 8628,X
STA DB00,X

LDA 7F40,X  ;Copy multi-color data to screen memory
STA 5C00,X
LDA 8040,X
STA 5D00,X
LDA 8140,X
STA 5E00,X
LDA 8240,X
STA 5F00,X

DEX
BNE 0857

LDA 8710
STA D021  ;Set VIC background color

LDX #01
STX D01A  ;Mask VIC raster interrupt
STX 0832  ;Enable the infinite loop above.

BIT DC0D  ;Enable CIA1's Interrupts

LDA #2E    
STA D012  ;Set VIC raster counter

LDA #78
STA D018  ;Set VIC memory pointers

LDA #02    
STA DD00  ;Set VIC memory bank

LDA #D8    
STA D016  ;Turn on VIC multi-color mode
RTS


;----[ IRQ Service Routine Wedge ]----

08B0:
LDA #01
STA D019   ;Clear Raster Interrupt
LDA DC01   ;Scan Keyboard Matrix
AND #10    ;Compare with space key column 
BNE 08C1   ;Skip if space not pressed

LDA #00    
STA 0832   ;Break the infinite loop above

08C1:
JMP EA81   ;Continue KERNAL IRQ routine