Note: Most of the register names come from neogeo_spex.pdf
Common registers
I/O registers
| Address
|
Name
|
Size
|
Read
|
Write
|
Handled by
|
| $300000
|
REG_P1CNT
|
Byte
|
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
|
Byte
|
Dipswitches (active low)
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
Freeze |
Freeplay | Coin meters ? | Autofire | ? | Test mode |
|
Kick watchdog
|
NEO-F0 (read)
|
| $300081
|
?
|
Byte
|
Read only
|
?
|
?
|
| $320000
|
REG_SOUND
|
Byte
|
Send command to Z80
|
Read Z80 reply code
|
NEO-D0 ?
|
| $320001
|
REG_STATUS_A
|
Byte
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
|
?
|
?
|
| $340000
|
REG_P2CNT
|
Byte
|
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
|
Byte
|
| 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
|
?
|
Byte
|
?
|
Joypad ports outputs
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
P2 outputs | P1 outputs |
MAME select_controller
|
NEO-D0
|
| $380011
|
?
|
Byte
|
?
|
Write only, after a write to $3A0019
|
?
|
| $380021
|
REG_SLOT
|
Byte
|
?
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
? |
Slot # |
|
NEO-F0?
|
| $380030(1?)
|
?
|
Byte
|
?
|
MAME set_output_latch (LED marquee ?)
|
NEO-F0?
|
| $380040(1?)
|
?
|
Byte
|
?
|
MAME set_output_data (LED marquee ?)
|
NEO-F0?
|
| $380050(1?)
|
?
|
Byte
|
?
|
MAME upd4990a_control_16_w (Calendar)
|
NEO-F0?
|
| $380061
|
?
|
Byte
|
?
|
Base address for writes (used by the MVS BIOS)
|
?
|
| $380065
|
?
|
Byte
|
?
|
Write only (used by the MVS BIOS)
|
?
|
| $380067
|
?
|
Byte
|
?
|
Write only (used by the MVS BIOS)
|
?
|
System registers
Handled by a 74HC259 adressable latch.
| Address
|
Name
|
Size
|
Read
|
Write
|
| $3A0001
|
REG_DISPENABL
|
Byte
|
Invalid
|
Normal video output
|
| $3A0011
|
REG_DISPDSABL
|
Byte
|
Invalid
|
Darken video output
|
| $3A0003
|
?
|
Byte
|
Invalid
|
Use the BIOS vector table
|
| $3A0013
|
REG_SWPROM
|
Byte
|
Invalid
|
Use the cart's vector table
|
| $3A0005
|
REG_CRDUNLOCK1
|
Byte
|
Invalid
|
Allow /WE to pass through to memory card when low
|
| $3A0015
|
REG_CRDLOCK1
|
Byte
|
Invalid
|
Don't allow /WE to pass through to memory card
|
| $3A0007
|
REG_CRDLOCK2
|
Byte
|
Invalid
|
Don't allow /WE to pass through to memory card
|
| $3A0017
|
REG_CRDUNLOCK1
|
Byte
|
Invalid
|
Allow /WE to pass through to memory card when high
|
| $3A0009
|
?
|
Byte
|
Invalid
|
?
|
| $3A0019
|
?
|
Byte
|
Invalid
|
?
|
| $3A000B
|
REG_BRDFIX
|
Byte
|
Invalid
|
Use the embeded fix tileset (SFIX)
|
| $3A001B
|
REG_CRTFIX
|
Byte
|
Invalid
|
Use the cart's fix tileset
|
| $3A000D
|
REG_SRAMLOCK
|
Byte
|
Invalid
|
Write-protects the SRAM (MVS)
|
| $3A001D
|
REG_SRAMULOCK
|
Byte
|
Invalid
|
Unprotects SRAM (MVS)
|
| $3A000F
|
REG_PALBANK1
|
Byte
|
Invalid
|
Use palette bank 1
|
| $3A001F
|
REG_PALBANK0
|
Byte
|
Invalid
|
Use palette bank 0
|
Video registers
Probably handled by the LSPC chips.
| 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
|
Word
|
REG_VRAMMOD
|
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 |
Raster line counter |
? | 1:50Hz
0:60Hz | Auto animation counter |
Line counter: (diagram needed)
$00F8-$00FF : Vertical sync
$0100-$010F : Top border
$0110-$01EF : Active display
$01F0-$01FF : Bottom border
|
| Bit |
15 |
14 |
13 |
12 |
11 |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
Auto animation speed (in frames) |
HBlank (RLI) interrupt mode | HBlank interrupt enabled | 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 only (from NeoCD's source)
NEO-MGA / LC8953 ?
| Address
|
Name
|
Size
|
Read
|
Write
|
Handled by
|
| $FF0002
|
?
|
Word
|
?
|
?
|
?
|
| $FF007E~$FF008F
|
?
|
Word
|
?
|
dma_mode
|
| $FF0105
|
?
|
Byte
|
?
|
upload_type_w
|
| $FF0111
|
?
|
Byte
|
?
|
spr_disable
|
| $FF0115
|
?
|
Byte
|
?
|
fix_disable
|
| $FF0119
|
?
|
Byte
|
?
|
video_enable
|
| $FF011C
|
?
|
Word
|
region_code, 0xFF
|
?
|
| $FF016F
|
?
|
Byte
|
?
|
disable_irq_w
|
| $FF0183
|
?
|
Byte
|
?
|
z80_enable
|
| $FF0188
|
?
|
Word
|
CDDA_LEFTSTREAM
|
?
|
NEO-MGA
|
| $FF018A
|
?
|
Word
|
CDDA_RIGHTSTREAM
|
?
|