Gdc I/O-Address And Bit Map - NEC Advanced Personal Computer System Reference Manual

Controller PCB
Table 3-2 GDC I/O-Address and Bit Map
I/O READ/ BIT MAP
ADDRESS WRITE 7
6
5 4
3
L H V
D
D
40 Read
M
P
B
S
A
W
40 Write
P P P P P
7
6
5 4
3
42 Read
D
D D D D
7 6 5 4 3
42 Write
C C C C C
7 6
5
4 3
46 Write
BIT
7 6
5
4
3
Figure 3-8 GDC Status Register Bit Map
2 I
0
F
F D
E
F
R
P P P
2 1
0
D D D
2 I 0
C C C
2
I
0
C
R
T
2
INSTRUCTION
Read Status Register
Write Parameter Register
Read Data Register
Write Command Register
Reset Interrupt Request
1
0
[
DATA READY
FIFO BUFFER FULL
FIFO BUFFER EMPTY
DRAWING
DMA EXECUTE
VERTICAL SYNC
HORIZONT AL BLANK
NOT USED
3-9