Accessing The Palette Registers; Accessing The Status Registers; Accessing The Video Ram - Yamaha V9938 Programmer's Manual

Note: data in register R#17 can not be changed by indirect addressing.
Register #17
Port #3 first byte
Port #3 second byte
...
th
Port #3 n byte

1.2. Accessing the Palette Registers

To set data in the MSX-VIDEO palette registers (P#0 to P#15) you must first set the
palette register number in register R#16 (Color palette address pointer) and subsequently
write two bytes of data (in specific order) into port #2. Every color consists of 3 sets of 3
bits: red, green and blue component (value 0...7).
Note: after writing pair of data to port #2 palette register number (pointer) in
register R#16 auto-increments.
Register #16
Port #2 first byte
Port #2 second byte

1.3. Accessing the status registers

To read the status registers of MSX-VIDEO (S#0 to S#9) you must first set the
register number in R#15 (Status register pointer) and then read data from port #1.
Register #15 (write)
Port #1 data (read)
© 1985 ASCII CORP. / NIPPON GAKKI CO.
MSB 7 6 5
AII 0 R5
0: Auto-increment is enabled
1: Auto-increment is disabled
D7 D6 D5
D7 D6 D5
D7 D6 D5
MSB 7 6 5
0 0 0
0 R2 R1
Red data
0 0 0
MSB 7 6 5
0 0 0
D7 D6 D5
4 3 2 1
R4 R3 R2 R1
D4 D3 D2 D1
D4 D3 D2 D1
D4 D3 D2 D1
4 3 2 1
0 C3 C2 C1
R0 0 B2 B1
Blue data
0 0 G2 G1
Green data
4 3 2 1
0 S3 S2 S1
D4 D3 D2 D1
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0 LSB
R0 Register #
D0 Data
D0 Data
D0 Data
0 LSB
C0 Palette #
B0 Data 1
G0 Data 2
0 LSB
S0 Stat Reg #
D0 Data read
© 2010-2015 Eugeny Brychkov