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# Mattel Aquarius 64 Color Flicker Mode

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I have put together a flicker mode demonstration. It is nothing fancy yet, but bear with me because I just learned assembler 2 days ago. What this program does is rapidly switch between two colors while waiting for a vertical refresh flag, meaning, it doesn't start drawing until it knows the last screen was done drawing. My assumption is that there is enough clock cycles to complete the task in a single frame - but I could be wrong. This is untested on an actual aquarius, but works well on the emulator. (Remember to have your timing set to NTSC.) Check it out and let me know what you think.

Basic Program

```
5 x=0:i=0:n=0
10 DATA 33,212,52,219,253,203,71,32,250,205,27,125,33,212,52,219,253
20 DATA 203,71,32,250,205,54,125,195,0,125,14,255,6,0,112,35,13,121,230
30 DATA 15,254,15,204,48,125,121,177,32,241,112,201,17,24,0,25,4,201
40 DATA 14,255,6,0,112,35,4,13,121,230,15,254,15,204,76,125,121,177,32
41 DATA 240,112,201,17,24,0,25,201
44 data -1
45 n=32000:
50 POKE 14341,INT(N/256):POKE 14340,N-256*PEEK(14341)
60 READ I:IF I=-1 GOTO 75
70 POKE N,I:N=N+1:GOTO 60
75 print chr\$(11);
80 print "            64 Flicker Color"
85 print "     256 Block Matrix Demonstration"
90 t=0
100 poke 13484+t,t:poke 13484+t+(17*40),t
110 poke 13484+((t+1)*40)-1,t:poke 13484+17+((t+1)*40)-1,t
120 t=t+1:if t<>16 then goto 100
130 x=usr(0)
140 goto 130

```

For the geeks, here is the ASM code:

```
; File: FLICK.ASM; Displays a 64 Color Aquarius "Mode"
;
; Use tasm (supplied with VirtualAquarius) to compile:
; tasm -80 -b test.asm
;
.org 32000			; Start Program at Memloc 32000

main:	ld  hl, 13524		; Set Memory Location to Color Video
delaya:	in a, (253)		; Read VSYNC Signal Flag
bit 0,a			; Test bit 1 of VSYNC signal
jr nz, delaya		; Loop and wait for the sync
call hblock		; Draw the horizontal block

ld hl, 13524		; Reset the Memloc
delayb: in a, (253)		; Read VSYNC Signal Flag
bit 0,a			; Test bit 1 of VSYNC signal
jr nz, delayb		; Loop and wait for the sync
call vblock		; Draw the vertical block

jp main

hblock:	ld  c, 255		; 16 Blocks x 16 Lines, c counter
ld  b, 0		; Start the Block at color 0
hloop:	ld  (hl), b		; Set the color
inc hl			; Move to next location
dec c			; drop the counter
ld  a, c		; check out the counter
AND 15			; Strip off first nibble
cp 15			; is the second nibble 15?
call z, nxtline		; go to the next line

ld a, c			; put the counter back in accumulator
or c			; Are we at zero?
jr nz, hloop		; if counter is nz repeat loop
ld (hl),b
ret			; if counter is z return

nxtline:ld de, 24		; Lines are 40 bytes long, at end of line, 40-16
add hl, de		; Add 40 to the memloc
inc b
ret

vblock:	ld  c, 255		; 16 Blocks x 16 Lines, c counter
ld  b, 0		; Start the Block at color 0
vloop:	ld  (hl), b		; Set the color
inc hl			; Move to next location
inc b
dec c			; drop the counter
ld  a, c		; check out the counter
AND 15			; Strip off first nibble
cp 15			; is the second nibble 15?
call z, ntline		; go to the next line

ld a, c			; put the counter back in accumulator
or c			; Are we at zero?
jr nz, vloop		; if counter is nz repeat loop
ld (hl),b
ret			; if counter is z return

ntline: ld de, 24		; Lines are 40 bytes long, at end of line, 40-16
add hl, de		; Add 40 to the memloc
ret
.END

```

flick.zip

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Check it out and let me know what you think.

Very funny, but I am not sure if I saw all 64 colors.

Good program!

Regs,

Martin

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Since my pc has a lot of processes running in the background (video editing, DVR, etc), I had to turn up the Aquarius processing speed to get the effect.

I could see a nice color gradient table forming.

Nice! I look forward to seeing this developed further.

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