| Address |
R/W |
Detail
|
| $D400
|
R
|
Keyboard data high bit
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
D8
|
|
|
| $D401
|
R
|
Keyboard data low 8 bits
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
Keyboard data bits 0~7
|
|
|
|
| $D402
|
R
|
Acknowledge IRQ from main CPU
|
|
|
| $D403
|
R
|
One-shot buzzer
|
|
|
| $D404
|
R
|
Send attention IRQ to main CPU
|
|
|
| $D405
|
W
|
Sub-CPU mode
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
FAST
|
| FAST
|
Set performance mode
Display steals cycles from CPU in Slow
|
0: Fast
1: Slow
|
CSCP emulator implies this port interacts with the 400 line board config.
|
|
|
| $D406
|
R
|
Kanji ROM data left byte
|
| W
|
Kanji ROM address high byte
|
| $D407
|
R
|
Kanji ROM data right byte
|
| W
|
Kanji ROM address low byte
|
|
|
| $D408
|
R
|
Turn display on
|
| W
|
Turn display off (show only black)
|
|
|
| $D409
|
R
|
Allow access to VRAM
When in Slow performance mode, this reduces performance to ~1/3
|
| W
|
Disable access to VRAM
|
|
|
| $D40A
|
R
|
Clear BUSY flag to main CPU
|
| W
|
Set BUSY flag to main CPU
|
|
|
| $D40B
|
RW
|
400-line card I/O
|
| $D40C
|
RW
|
400-line card I/O
|
|
|
| $D40D
|
R
|
Turn on INS LED on keyboard (?)
|
| W
|
Turn off INS LED on keyboard (?)
|
|
|
| $D40E
|
W
|
VRAM offset address high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
OA14
|
OA13
|
OA12
|
OA11
|
OA10
|
OA9
|
OA8
|
OA14 only available in 400-line mode.
|
| $D40F
|
W
|
VRAM offset address low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
OA7
|
OA6
|
OA5
|
OA4
|
OA3
|
OA2
|
OA1
|
OA0
|
OA4~OA0 only available on L4 and AV when enabled in $D430.
Together with $D40E, determines VRAM access offset.
This offset is used both for the CPU and the display.
|
| $D410
|
RW
|
ALU command register
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
EST
|
M1
|
M2
|
|
ALGO
|
| EST
|
Process ALU command
|
0: Do not process
1: Process
|
| M1
|
? TODO
|
? TODO
|
| M2
|
? TODO
|
0: Write with イコール
1: Write with NOTイコール
|
| ALGO
|
ALU math algorithm
|
000: PSET
001: Don't Use
010: OR
011: AND
100: XOR
101: NOT
110: TILEPAINT
111: COMPARE
|
|
| $D411
|
RW
|
ALU logical color
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
G
|
R
|
B
|
|
| $D412
|
RW
|
ALU mask register
|
| $D413
|
RW?
|
ALU compare registers
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
MASK
|
|
G
|
R
|
B
|
|
| $D414
|
| $D415
|
| $D416
|
| $D417
|
| $D418
|
| $D419
|
| $D41A
|
| $D41B
|
RW
|
ALU bank disable register
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
1
|
G
|
R
|
B
|
|
| $D41C
|
W
|
ALU tile paint register B
|
| $D41D
|
W
|
ALU tile paint register R
|
| $D41E
|
W
|
ALU tile paint register G
|
| $D420
|
W
|
ALU address offset register high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
A13~A9
|
|
| $D421
|
W
|
ALU address offset register low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
A8~A1
|
TODO
|
| $D422
|
W
|
ALU line style pattern register high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
P15~P8
|
|
| $D423
|
W
|
ALU line style pattern register low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
P7~P0
|
TODO
|
| $D424
|
W
|
ALU X start position high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
X9~X8
|
|
| $D425
|
W
|
ALU X start position low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
X7~X0
|
TODO
|
| $D426
|
W
|
ALU Y start position high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
Y8
|
|
| $D427
|
W
|
ALU Y start position low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
Y7~Y0
|
TODO
|
| $D428
|
W
|
ALU X end position high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
X9~X8
|
|
| $D429
|
W
|
ALU X end position low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
X7~X0
|
TODO
|
| $D42A
|
W
|
ALU Y end position high byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
Y8
|
|
| $D42B
|
W
|
ALU Y end position low byte
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
Y7~Y0
|
TODO
|
|
|
| $D42E
|
W
|
Sub-RAM bank select (AV40 only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
KNJSEL
|
|
SRA
|
SRB
|
| KNJSEL
|
Select kanji ROM
|
0: Level 1
1: Level 2
|
| SRA
|
Console RAM bank
|
| SRB
|
CG RAM bank
|
|
|
|
| $D42F
|
W
|
VRAM bank select (AV40 only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
BS
|
VRAM bank select (value 11 is invalid)
|
|
|
| $D430
|
R
|
Miscellaneous status (AV only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
BLANK
|
|
BUSY
|
|
VSYNC
|
|
RESET
|
| BLANK
|
Current blanking status
|
0: Blanking
1: Display
|
| BUSY
|
Current BUSY state
|
0: Busy
1: Ready
|
| VSYNC
|
Current VSYNC state
|
0: Vdisp
1: Vsync
|
|
| W
|
Miscellaneous flags (AV only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
NMIMASK
|
DISPPG
|
ACTPG
|
|
OFSLOEN
|
CGBANK
|
| NMIMASK
|
NMI mask register (yes really...)
|
0: Enabled
1: Disabled
|
| DISPPG
|
Display page
|
0: Page 0
1: Page 1
|
| ACTPG
|
Active page
|
| OFSLOEN
|
Offset register OA4~OA0 enable
|
0: Disabled
1: Enabled
|
| CGBANK
|
CG ROM bank
|
|
|
|
| $D431
|
RW
|
Keyboard encoder data register (AV only)
TODO
|
| $D432
|
R
|
Keyboard encoder status register (AV only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
LATCH
|
|
ACK
|
| LATCH
|
Data receive validity
|
0: Allowed
1: Not allowed
|
| ACK
|
Data send status
|
0: Not complete
1: Complete
|
|
|
|
| $D433
|
W
|
VRAM block select (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
DISPBLK
|
|
ACTBLK
|
| DISPBLK
|
Display block
|
0: Block 0
1: Block 1
|
| ACTBLK
|
Active block
|
|
|
|
| $D438
|
W
|
Window X start position high byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
XWS-A9~XWS-8
|
|
| $D439
|
W
|
Window X start position low byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
XWS-A7~XWS-A3
|
|
|
| $D43A
|
W
|
Window X end position high byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
XWE-A9~XWE-A8
|
|
| $D43B
|
W
|
Window X end position low byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
XWE-A7~XWE-A3
|
|
|
| $D43C
|
W
|
Window Y start position high byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
YWS-A9~YWS-A8
|
|
| $D43D
|
W
|
Window Y start position low byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
YWS-A7~YWS-A0
|
|
| $D43E
|
W
|
Window Y end position high byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
YWE-A9~YWE-A8
|
|
| $D43F
|
W
|
Window Y end position low byte (AV40EX only)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
YWE-A7~YWE-A0
|
All of the window position registers are used together.
Defines a window in which the opposite block from the one specified in DISPBLK in $D433 will be displayed.
If both start coordinates are beyond the end coordinates, the condition is inverted.
|