Note: Most of the register names come from neogeo_spex.pdf
I/O registers
Always read/written as bytes (?)
| Address
|
Name
|
Read
|
Write
|
Handled by
|
| $300000
|
REG_P1CNT
|
Player 1 controls (active low)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
D |
C | B | A | Right | Left | Down | Up |
|
?
|
NEO-C1
|
| $300001
|
REG_DIPSW
|
Dipswitches (active low)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
Freeze |
Freeplay | Multiplayer configuration | Controller mode (normal or mahjong) | Coin mode (normal or versus) | Test mode |
|
Kick watchdog
|
NEO-F0 (read)
|
| $300081
|
?
|
Read only
|
?
|
?
|
| $320000
|
REG_SOUND
|
Send command to Z80
|
Read Z80 reply code
|
NEO-D0 ?
|
| $320001
|
REG_STATUS_A
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
NEC D4990 data bit |
NEC D4990 time pulse | ? | Service | Coin 2 | Coin 1 |
|
?
|
?
|
| $340000
|
REG_P2CNT
|
Player 2 controls (active low)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
D |
C | B | A | Right | Left | Down | Up |
|
?
|
NEO-C1
|
| $380000
|
REG_STATUS_B
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
Memory card
write protect | Memory card
inserted | Select P2 | Start P2 | Select P1 | Start P1 |
|
?
|
NEO-C1
|
| $380001
|
REG_POUTPUT
|
?
|
Joypad ports outputs
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
P2 outputs | P1 outputs |
MAME select_controller
|
NEO-D0
|
| $380011
|
?
|
?
|
Write only, after a write to $3A0019
|
?
|
| $380021
|
REG_SLOT
|
?
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
Slot # |
|
NEO-F0?
|
| $380030(1?)
|
?
|
?
|
MAME set_output_latch (LED marquee ?)
|
NEO-F0?
|
| $380040(1?)
|
?
|
?
|
MAME set_output_data (LED marquee ?)
|
NEO-F0?
|
| $380050(1?)
|
?
|
?
|
MAME upd4990a_control_16_w (Calendar)
|
NEO-F0?
|
| $380061
|
?
|
?
|
Base address for writes (used by the MVS BIOS)
|
?
|
| $380065
|
?
|
?
|
Write only (used by the MVS BIOS)
|
?
|
| $380067
|
?
|
?
|
Write only (used by the MVS BIOS)
|
?
|
| $3800E1
|
?
|
?
|
Write only (used by the MVS BIOS)
|
?
|
System registers
Handled by a 74HC259 adressable latch on cart systems. Byte writes only.
| Address
|
Name
|
Write
|
| $3A0001
|
REG_DISPENABL
|
Normal video output
|
| $3A0011
|
REG_DISPDSABL
|
Darken video output
|
| $3A0003
|
REG_SWPBIOS
|
Use the BIOS vector table
|
| $3A0013
|
REG_SWPROM
|
Use the cart's vector table
|
| $3A0005
|
REG_CRDUNLOCK1
|
Enable writes to memory card (use REG_CRDUNLOCK2 too)
|
| $3A0015
|
REG_CRDLOCK1
|
Disable writes to memory card
|
| $3A0007
|
REG_CRDLOCK2
|
Disable writes to memory card
|
| $3A0017
|
REG_CRDUNLOCK2
|
Enable writes to memory card (use REG_CRDUNLOCK1 too)
|
| $3A0009
|
?
|
?
|
| $3A0019
|
?
|
?
|
| $3A000B
|
REG_BRDFIX
|
Use the embedded SFIX and SM1 ROM
|
| $3A001B
|
REG_CRTFIX
|
Use the cart's S ROM and M ROM
|
| $3A000D
|
REG_SRAMLOCK
|
Write-protects SRAM (MVS)
|
| $3A001D
|
REG_SRAMULOCK
|
Unprotects SRAM (MVS)
|
| $3A000F
|
REG_PALBANK1
|
Use palette bank 1
|
| $3A001F
|
REG_PALBANK0
|
Use palette bank 0
|
Video registers
Handled by the GPUs.
| Address
|
Name
|
Size
|
Read
|
Write
|
| $3C0000
|
REG_VRAMADDR
|
Word
|
Read VRAM (address isn't changed)
|
Sets VRAM address
|
| $3C0002
|
REG_VRAMRW
|
Word
|
Read VRAM (address isn't changed)
|
Write VRAM
|
| $3C0004
|
REG_VRAMMOD
|
Word
|
Reads VRAM address modulo
|
Sets VRAM address modulo (signed)
|
| $3C0006
|
REG_HBLANKCNT
|
Word
|
|
| Bit |
15 |
14 |
13 |
12 |
11 |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
Auto animation speed
(in frames) |
Raster interrupt
mode | Raster interrupt
enable | Disable auto animation | ? |
|
| $3C0008
|
REG_HBLANKPOS
|
Word
|
Invalid
|
MSB of RLI position (number of pixels)
|
| $3C000A
|
?
|
Word
|
Invalid
|
LSB of RLI position (number of pixels)
|
| $3C000C
|
REG_IRQACK
|
Byte
|
Invalid
|
Interrupt Acknowledge.
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
Ack VBlank | Ack HBlank | Ack IRQ3 |
|
| $3C000E
$3C000F
|
?
|
?
|
Some emulators treat these locations like $3C000A.
|
NeoGeo CD registers
NEO-MGA / LC8953 / LC98000 ?
| Address
|
Name
|
Size
|
Read
|
Write
|
Handled by
|
| $FF0002
|
?
|
Word
|
?
|
NeoRaine load_files
|
?
|
| $FF0004
|
?
|
Word
|
?
|
CDM3-2 BIOS writes 0,1,3,7
|
?
|
| $FF000E
|
?
|
Byte
|
?
|
CDM3-2 BIOS writes $3F,$3C
|
?
|
| $FF000F
|
?
|
Byte
|
?
|
CDM3-2 BIOS writes $20,$10,$08,$04
|
?
|
| $FF0011
|
?
|
Byte
|
?
|
CDM3-2 BIOS writes $FE
|
?
|
| $FF0017
|
?
|
Byte
|
CDM3-2 BIOS read/writes bit 0
|
?
|
| $FF0061
|
?
|
Byte
|
?
|
Bit4: Run microcode ?
|
LC8953
|
| $FF0064~$FF0070
|
?
|
(Long)words
|
?
|
Registers used by microcode (NeoRaine upload_param)
|
| $FF007E~$FF008F
|
?
|
Words
|
?
|
Microcode (16x9bit instructions ?)
|
| $FF0101
|
?
|
Byte
|
?
|
CDM3-2 BIOS writes low nibble
|
?
|
| $FF0103
|
?
|
Byte
|
CDM3-2 BIOS: sequential read/writes
|
?
|
| $FF0105
|
?
|
Byte
|
?
|
upload_type_w
|
?
|
| $FF0108
|
?
|
Word
|
?
|
CDM3-2 BIOS writes $5555
|
?
|
| $FF010C
|
?
|
Word
|
?
|
CDM3-2 BIOS writes $5555 and reads
|
?
|
| $FF0111
|
REG_DISBLSPR
|
Byte
|
?
|
Disable/enable sprites ?
|
NEO-GRC/NEO-OFC
|
| $FF0115
|
REG_DISBLFIX
|
Byte
|
?
|
Disable/enable fix layer ?
|
| $FF0119
|
REG_ENVIDEO
|
Byte
|
?
|
Enable/disable video output ? (disable works)
|
| $FF011C
|
REG_CDCONFIG
|
Word
|
| Bit |
15 |
14 |
13 |
12 |
11 |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
1 |
0 | CD lid switch | Configuration jumpers | ? |
|
No effect
|
NEO-CDD board
|
| $FF0121
|
REG_UPMAPSPR
|
Byte
|
?
|
Set upload zone to SPR DRAM
|
?
|
| $FF0123
|
REG_UPMAPPCM
|
Set upload zone to PCM DRAM
|
| $FF0127
|
REG_UPMAPZ80
|
Set upload zone to Z80 DRAM
|
| $FF0129
|
REG_UPMAPFIX
|
Set upload zone to FIX DRAM
|
| $FF0141
|
REG_UPUNMAPSPR
|
Unset SPR DRAM to upload zone
|
| $FF0143
|
REG_UPUNMAPPCM
|
Unset PCM DRAM to upload zone
|
| $FF0147
|
REG_UPUNMAPZ80
|
Unset Z80 DRAM to upload zone
|
| $FF0149
|
REG_UPUNMAPFIX
|
Unset FIX DRAM to upload zone
|
| $FF016F
|
REG_DISBLIRQ
|
Byte
|
?
|
Disable/enable interrupts
|
?
|
| $FF0183
|
REG_ENZ80
|
Byte
|
?
|
Enable/disable(reset) Z80
|
?
|
| $FF0188
|
REG_CDDALEFTL
|
Word
|
See Reading CDDA sound levels
|
No effect
|
NEO-MGA
|
| $FF018A
|
REG_CDDARIGHTL
|
| $FF01A1
|
?
|
Byte
|
?
|
Upload zone 1MiB SPR DRAM bank selection
|
?
|
| $FF01A3
|
?
|
Byte
|
?
|
Upload zone 1MiB PCM DRAM bank selection
|
?
|
| $FF01A7
|
?
|
Byte
|
?
|
CDM3-2 BIOS writes
|
?
|
| $FF01FC
|
?
|
Word
|
?
|
CDDA control ?
|
?
|
| $FF01FE
|
?
|
Word
|
?
|
CD DA/data switch ?
|
?
|