AMSTRAD CPC SCREEN HELP - WORKED OUT BY N.W.C. 4-7-1987.
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NORMAL SCREEN START : &C000/49152
NORMAL SCREEN END : &FFCF/65487
MODE 0:
SCREEN BYTE: PIXEL A, PIXEL B
PIXEL A: BIT 7 5 3 1
PIXEL B: BIT 6 4 2 0
BIT PEN VALUE BYTE VALUE PIXEL
0 8 1 B
1 8 2 A
2 2 4 B
3 2 8 A
4 4 16 B
5 4 32 A
6 1 64 B
7 1 128 A
MODE 1:
SCREEN BYTE: PIXEL A, PIXEL B, PIXEL C, PIXEL D
PIXEL A: BIT 7 3
PIXEL B: BIT 6 2
PIXEL C: BIT 5 1
PIXEL D: BIT 4 0
BIT PEN VALUE BYTE VALUE PIXEL
0 2 1 D
1 2 2 C
2 2 4 B
3 2 8 A
4 1 16 D
5 1 32 C
6 1 64 B
7 1 128 A
MODE 2:
SCREEN BYTE: PIXEL A,B,C,D,E,F,G,H
PIXEL A: BIT 7
PIXEL B: BIT 6
PIXEL C: BIT 5
PIXEL D: BIT 4
PIXEL E: BIT 3
PIXEL F: BIT 2
PIXEL G: BIT 1
PIXEL H: BIT 0
PEN VALUE: PEN 0=BIT RESET/PEN 1=BIT SET