A86: Grayscale


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A86: Grayscale



I was working on a little grayscale program last night, but I was unable to
get it to display gray.

I used the following code ($E000 and $E400 are the 2 pics in my code)

Loop:
 ld a,$20
 out (0),a
 ;a whole bunch of nops - I tried anywhere from 0 to 100...
 ld a,$24
 out (0),a
 ;whole bunch more nops - same as above...
 call _getkey
 cp kExit
 jr z,FixScreen
 jr Loop
FixScreen:
 ld a,$3C
 out (0),a
 ret

When I put pauses directly after each out (0),a, it switches the screen like
I want it to, but when I take out both pauses and use the above code, it just
shows one of them the whole time, until I hit escape...

Also, I tried loading the entire pic into vid mem (before I changed it) with
an ldir and it never worked...  I used the following code:

 ld hl,Pic0
 ld de,$FC00
 ld bc,1024
 ldir
 ;.......
Pic0:
 .db 0,0,0,0,0,0,0   ;1024 zeros with 4 1 bits in the middle...
 ;etc...

Anyone know why either of these didn't work?

~Steve