| Address |
R/W |
Detail
|
| $FD00
|
R
|
Keyboard data high bit, and clock speed indicator
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
D8
|
|
CLK
|
| D8
|
Keyboard data bit 8
|
|
| CLK
|
Clock speed
|
0: 1.2MHz
1: 2MHz
AV always reads '1'
|
|
| W
|
Audio cassette and printer
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
SLCTIN
|
STRB
|
|
CASRMT
|
CASWR
|
| SLCTIN
|
Printer select input
|
0: Select
1: Unselect
|
| STRB
|
Printer strobe
|
Strobe for data exchange (edge pulse)
|
| CASRMT
|
Audio cassette remote
|
0: ON
1:OFF
|
| CASWR
|
Audio cassette data
|
Write data, MIC
|
|
|
|
| $FD01
|
R
|
Keyboard data low 8 bits
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
Keyboard data bits 0~7
|
|
| W
|
Printer output data
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
Output data
|
|
|
|
| $FD02
|
R
|
Audio cassette and printer
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
CASRD
|
|
DET2
|
DTT1
|
PE
|
ACKNG
|
ERROR
|
BUSY
|
| CASRD
|
Cassette data read, SPK
|
|
| DET2
|
Printer DET 2
|
(unused)
|
| DTT1
|
Printer DTT 1
|
(unused)
|
| PE
|
Printer Paper Empty
|
0: Normal
1: No paper
|
| ACKNG
|
Acknowledge
|
Triggered by reading (?)
|
| ERROR
|
Printer Error
|
0: Error
1: Normal
|
| BUSY
|
Printer Busy
|
0: Ready
1: Busy
|
|
| W
|
IRQ mask
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
SYNDET
|
RXRDY
|
TXRDY
|
MFD
|
|
TIMER
|
PRINTER
|
KEY
|
| SYNDET
|
RS-232 sync detect
|
0: Disable
1: Enable
|
| RXRDY
|
RS-232 serial receive ready
|
| TXRDY
|
RS-232 serial transmit ready
|
| MFD
|
Mini-floppy disk
|
| TIMER
|
Periodic timer (every 2.03ms)
|
| PRINTER
|
Printer ready for next character
|
| KEY
|
Keystroke received
|
|
|
|
| $FD03
|
R
|
IRQ flags
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
EXT
|
TIMER
|
PRINTER
|
KEY
|
| EXT
|
Expansion
|
0: Active
1: Inactive
|
| TIMER
|
Periodic timer
|
| PRINTER
|
Printer ready for next character
|
| KEY
|
Keystroke received
|
|
| W
|
Buzzer
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
REPEAT
|
SINGLE
|
|
SPEAKER
|
| REPEAT
|
Repeating buzzer
|
0: Off
1: On
|
| SINGLE
|
One-shot buzzer
|
0: Off
1: On
|
| SPEAKER
|
Output buzzer to speaker
|
0: Mute
1: Output
|
|
|
|
| $FD04
|
R
|
Sub-CPU interface, FIRQ flags
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
FDCMODE
|
KNJMODE
|
400CARD
|
400LINE
|
IRQMODE
|
BREAK
|
ATN
|
| FDCMODE
|
FDC mode
|
0: 1MB
1: 320KB
|
L4 only
|
| KNJMODE
|
Kanji ROM mode
|
0: SUB
1: MAIN
|
L4 only
|
| 400CARD
|
400-line card
(260k color mode for AV40?)
|
0: Enable(?)
1: Disable(?)
|
L4 only
|
| 400LINE
|
400-line mode
|
0: 400-line
1: 200-line
|
L4 only
|
| IRQMODE
|
IRQ mode
|
0: Normal
1: SFD
|
L4 only
|
| BREAK
|
Break key pressed
|
0: Active
1: Inactive
|
| ATN
|
Sub-CPU attention signal
|
|
| W
|
Sub-CPU interface
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
FDCMODE
|
KNJMODE
|
400CARD
|
400LINE
|
IRQMODE
|
|
| FDCMODE
|
FDC mode
|
0: 1MB
1: 320KB
|
L4 only
|
| KNJMODE
|
Kanji ROM mode
|
0: SUB
1: MAIN
|
L4 only
|
| 400CARD
|
400-line card
(260k color mode for AV40?)
|
0: Enable(?)
1: Disable(?)
|
L4 only
|
| 400LINE
|
400-line mode
|
0: 400-line
1: 200-line
|
L4 only
|
| IRQMODE
|
IRQ mode
|
0: Normal
1: SFD
|
L4 only
|
|
|
|
| $FD05
|
R
|
Sub-CPU status, expansion status
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
BUSY
|
|
EXTDET
|
| BUSY
|
Sub-CPU busy signal
|
0: Ready
1: Busy
|
| EXTDET
|
Expansion card presence
|
0: Present
1: Not present
|
|
| W
|
Sub-CPU status, expansion status
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
HALT
|
CANSEL
|
|
| HALT
|
Halt sub-CPU execution
|
0: Run
1: Halt
|
| CANSEL
|
Send IRQ to sub-CPU
|
0: No
1: Yes
|
|
|
|
| $FD06
|
RW
|
RS-232 data
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
RS-232 data
|
Read to receive, write to transmit.
|
|
|
| $FD07
|
RW
|
RS-232 command and status (TODO)
|
|
|
| $FD08
|
RW
|
Light pen (TODO)
|
|
|
| $FD09
|
RW
|
Light pen (TODO)
|
|
|
| $FD0A
|
RW
|
Light pen (TODO)
|
|
|
| $FD0B
|
R
|
Boot switch status, RS-232 interface
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
CD
|
|
MODE
|
| CD
|
RS-232 Carrier Detect
|
0: On
1: Off
|
AV20, AV40 only
|
| MODE
|
Boot mode switch
|
0: BASIC
1: DOS
|
AV only
|
|
| W
|
RS-232 interface configuration
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
CLKSEL
|
BAUD
|
|
| CLKSEL
|
RS-232 clock select
|
TODO
|
AV20, AV40 only
|
| BAUD
|
RS-232 baud rate
|
TODO
|
AV20, AV40 only
|
|
|
|
| $FD0C
|
W
|
RS-232 interface configuration
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
DTR
|
|
ENABLE
|
| DTR
|
RS-232 DTR
|
0: Output
1: Prohibit
|
AV20, AV40 only
|
| ENABLE
|
RS-232 enable
|
0: Disable
1: Enable
|
AV20, AV40 only
|
|
|
|
| $FD0D
|
W
|
PSG command register
|
|
|
| $FD0E
|
RW
|
PSG data register
|
|
|
| $FD0F
|
RW
|
ROM bank mode
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
MODE
|
| MODE
|
Change ROM bank status by access type
|
Read: ROM
Write: RAM
|
|
|
|
| $FD10
|
W
|
Initiator ROM disable
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
INITROM
|
|
| INITROM
|
Initiator ROM enable
|
0: Enabled
1: Disabled
|
AV only
|
|
|
|
| $FD12
|
R
|
Sub monitor status register
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
320MODE
|
1
|
DISPTMG
|
VSYNC
|
| 320MODE
|
320/640 mode
|
0: 640
1: 320
|
AV only
|
| DISPTMG
|
Display timing status
|
0: Blanking
1: Display
|
AV only
|
| VSYNC
|
V-sync status
|
1: Active time (TODO: are you sure?)
|
AV only
|
|
| W
|
Sub monitor status register
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
320MODE
|
0
|
| 320MODE
|
320/640 mode
|
0: 640
1: 320
|
AV only
|
|
|
|
| $FD13
|
W
|
Sub-bank register
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0
|
| Name
|
|
SB
|
| SB Value |
Behavior |
Valid System
|
| 000
|
Old Sub Monitor (Type C) (640x200) |
All
|
| 001
|
New Sub Monitor (Type A) (640x200) |
AV
|
| 010
|
New Sub Monitor (Type B) (320x200) |
AV
|
| 011
|
Prohibited
|
| 1XX
|
Sub Monitor RAM |
AV40
|
|
|
|
| $FD15
|
W
|
FM control register
|
|
|
| $FD16
|
RW
|
FM data register
|