one cycle

This is a program to flip graphics modes in one cycle to produce more seemingly impossible graphics gymnastics for a computer made in 1977.

This is very untested. I have no real hardware to test this on. It seems to break an older version 1.26.0.5 of AppleWin that I was using via wine on Linux. I downloaded a newer version AppleWin1.26.1.1 and did only a little bit of testing. Currently, I am testing it on KEGSMAC version 0.91 on a PowerPC Mac.

• Fill video memory with $4C bytes.
• Turn on graphics.
• Flip between hi-res and lo-res within 13 cycles.

There should be no rest for emulators trying to simulate the intricacies of old hardware.

onecycle.bas.txt

100   FOR I = 768 TO 820
110       READ B : POKE I, B : NEXT
120   FOR I = 19532 TO 19540
130       READ B : POKE I, B : NEXT
140   CALL 768 : END

200   DATA169,76,133,76,133,77
210   DATA133,78,162,4,160,8,32
220   DATA34,3,162,32,160,64,32
230   DATA34,3,44,80,192,32,76
240   DATA76,44,16,192,76,57
250   DATA251,132,235,160,0,132
260   DATA236,134,237,145,236
270   DATA200,208,251,232,228
280   DATA235,208,244,96

300   DATA173,0,192,16,1,96,76
310   DATA86,192

onecycle.s

	ORG $300
	LDA #$4C
	STA $4C
	STA $4D
	STA $4E
	LDX #$04
	LDY #$08
	JSR FILL
	LDX #$20
	LDY #$40
	JSR FILL
	BIT $C050
	JSR $4C4C
	BIT $C010
	JMP $FB39 ; TEXT
FILL
	STY $EB
	LDY #$00
	STY $EC
LOOP2
	STX $ED
LOOP
	STA ($EC),Y
	INY
	BNE LOOP
	INX
	CPX $EB
	BNE LOOP2
	RTS

vapor.s

	ORG $4C4C
VAPOR
	LDA $C000
	BPL REPEAT
	RTS
REPEAT
	JMP $C056