NeoGeo Development Wiki - User contributions [en]

Playing sound samples

2026-10-04T01:29:45Z

Furrtek: /* ADPCM-A */

==[[ADPCM]]-A==

Definitions of [[YM2610_registers#ADPCM-A part|ADPCM-A registers]]:

<syntaxhighlight lang="z80">
;ADPCM-A register defines (YM2610 port B: address $06, data $07)
PA_CTRL: EQU $00 ;bit 7: 0 = key on, 1 = dump (key off). Bits 0-5: channel mask
PA_MVOL: EQU $01 ;master volume, 0-$3F ($3F = loudest)
PA_CVOL: EQU $08 ;+channel: bit 7 = left, bit 6 = right, bits 0-4 = volume 0-$1F
PA_STARTL: EQU $10 ;+channel: start address bits 8-15
PA_STARTH: EQU $18 ;+channel: start address bits 16-23
PA_ENDL: EQU $20 ;+channel: end address bits 8-15
PA_ENDH: EQU $28 ;+channel: end address bits 16-23
</syntaxhighlight>

(Full list of defines [[YM2610 ASM defines|here]])

Registers marked "+channel" exist once per channel: add the channel number (0-5) to the base address. For example, the start address low register of CH3 is PA_STARTL+2 = $12. In PA_CTRL, bit 0 is CH1 and bit 5 is CH6, so several channels can be keyed on or off with a single write.

===Writing to the YM2610===
The real YM2610 requires a minimum delay between writes, see [[Z80/YM2610 interface]].

<syntaxhighlight lang="z80">
ORG $0018
jp WritePortB ;RST $18 vector (only 8 bytes available here, so jump)

;Write E to YM2610 port B register D (ADPCM-A, FM channels 3-4)
;Destroys: nothing
WritePortB:
push af
WPB_wait1:
in a,($04) ;status 0
rlca ;busy flag -> carry
jr c,WPB_wait1
ld a,d
out ($06),a ;register number
WPB_wait2:
in a,($04)
rlca
jr c,WPB_wait2
ld a,e
out ($07),a ;value
pop af
ret

;Write E to YM2610 port A register D (SSG, ADPCM-B, FM channels 1-2, flag control)
WritePortA:
push af
WPA_wait1:
in a,($04)
rlca
jr c,WPA_wait1
ld a,d
out ($04),a
WPA_wait2:
in a,($04)
rlca
jr c,WPA_wait2
ld a,e
out ($05),a
pop af
ret
</syntaxhighlight>

===Playing a sample===
Example: play V ROM $000000-$00FFFF on CH1, centered, at maximum volume. The start and end addresses must be written before the channel is keyed on. The master volume is global, so it usually only needs to be set once, at driver initialization.

<syntaxhighlight lang="z80">
;playback parameters
CH: EQU 0 ;channel 0-5 (0 = CH1)
MVOL: EQU $3F ;master volume
CVOL: EQU $C0+$1F ;left + right, channel volume $1F
START_ADDR: EQU $000000 ;first byte of the sample in V ROM
END_ADDR: EQU $00FFFF ;last byte of the sample (inclusive)

PlayADPCMA:
ld de,(PA_MVOL<<8)+MVOL
rst $18
ld de,((PA_CVOL+CH)<<8)+CVOL
rst $18
ld de,((PA_STARTL+CH)<<8)+((START_ADDR>>8)&$FF)
rst $18
ld de,((PA_STARTH+CH)<<8)+((START_ADDR>>16)&$FF)
rst $18
ld de,((PA_ENDL+CH)<<8)+((END_ADDR>>8)&$FF)
rst $18
ld de,((PA_ENDH+CH)<<8)+((END_ADDR>>16)&$FF)
rst $18
ld de,(PA_CTRL<<8)+(1<<CH) ;key on
rst $18
ret
</syntaxhighlight>

Keying on a channel that is already playing restarts it from its start address. When the channel reaches its end address it stops on its own and sets its end flag; there is no looping.

===Stopping a sample===
Writing PA_CTRL with bit 7 set stops (dumps) the channels selected in bits 0-5:

<syntaxhighlight lang="z80">
StopADPCMA:
ld de,(PA_CTRL<<8)+$80+(1<<CH) ;dump CH
rst $18
ret
</syntaxhighlight>

Writing $BF stops all six channels.

===End flags===
The end flags of the ADPCM-A channels can be read in bits 0-5 of status 1 (port $06); bit 7 is the ADPCM-B end flag. A flag stays set until it is cleared through the flag control register $1C on port A. Writing 1 to a bit clears and masks that flag, and writing 0 unmasks it again so it can be set by the next sample end.

<syntaxhighlight lang="z80">
;Z flag clear on return if CH has finished playing
CheckADPCMAEnd:
in a,($06) ;status 1
and 1<<CH
ret

;Clear the end flag of CH
ClearADPCMAEnd:
ld de,($1C<<8)+(1<<CH) ;clear and mask
call WritePortA
ld de,($1C<<8)+$00 ;unmask
call WritePortA
ret
</syntaxhighlight>

==ADPCM-B==
The YM2610 has one ADPCM-B channel. It plays 4-bit ADPCM samples at a variable rate, from about 1.85 kHz to 55.5 kHz, and can loop. This makes it suited to music, longer ambience and voice. Like ADPCM-A, samples are addressed in 256-byte units with an inclusive end address. Depending on the cartridge board, ADPCM-B samples are read from the same V ROM as ADPCM-A or from a separate ROM.

The ADPCM-B registers are on YM2610 '''port A''': the Z80 writes the register number to port '''$04''' and the value to port '''$05''' (see WritePortA above).

Definitions of [[YM2610_registers#ADPCM-B part|ADPCM-B registers]]:

<syntaxhighlight lang="z80">
;ADPCM-B register defines (YM2610 port A: address $04, data $05)
PB_CTRL1: EQU $10 ;bit 7 = start, bit 4 = repeat, bit 0 = reset
PB_CTRL2: EQU $11 ;bit 7 = left, bit 6 = right
PB_STARTL: EQU $12 ;start address bits 8-15
PB_STARTH: EQU $13 ;start address bits 16-23
PB_ENDL: EQU $14 ;end address bits 8-15
PB_ENDH: EQU $15 ;end address bits 16-23
PB_DELTAL: EQU $19 ;Delta-N (playback rate) low byte
PB_DELTAH: EQU $1A ;Delta-N high byte
PB_VOL: EQU $1B ;volume, 0-$FF ($FF = loudest)
</syntaxhighlight>

===Playback rate===
The playback rate is set by the 16-bit Delta-N value:

rate = 55.5 kHz × Delta-N / 65536
Delta-N = rate × 65536 / 55555

For example, a sample recorded at 22050 Hz needs Delta-N = 26011 ($659B), and one at 11025 Hz needs 13006 ($32CE). Changing Delta-N while the sample plays changes its pitch, which can be used to play one sample at different notes.

===Playing a sample===
Example: play V ROM $100000-$13FFFF on ADPCM-B at 22050 Hz, centred, at maximum volume. All parameters must be written before the start bit is set. The pan bits in PB_CTRL2 must be set, otherwise nothing is heard.

<syntaxhighlight lang="z80">
;playback parameters
B_START: EQU $100000 ;first byte of the sample in V ROM
B_END: EQU $13FFFF ;last byte of the sample (inclusive)
B_DELTA: EQU $659B ;22050 Hz
B_VOL: EQU $FF
B_PAN: EQU $C0 ;left + right

PlayADPCMB:
ld de,(PB_CTRL1<<8)+$01 ;reset, in case a sample is playing
call WritePortA
ld de,(PB_CTRL1<<8)+$00
call WritePortA
ld de,(PB_CTRL2<<8)+B_PAN
call WritePortA
ld de,(PB_STARTL<<8)+((B_START>>8)&$FF)
call WritePortA
ld de,(PB_STARTH<<8)+((B_START>>16)&$FF)
call WritePortA
ld de,(PB_ENDL<<8)+((B_END>>8)&$FF)
call WritePortA
ld de,(PB_ENDH<<8)+((B_END>>16)&$FF)
call WritePortA
ld de,(PB_DELTAL<<8)+(B_DELTA&$FF)
call WritePortA
ld de,(PB_DELTAH<<8)+(B_DELTA>>8)
call WritePortA
ld de,(PB_VOL<<8)+B_VOL
call WritePortA
ld de,(PB_CTRL1<<8)+$80 ;start ($90 = start with repeat)
call WritePortA
ret
</syntaxhighlight>

With the repeat bit set ($90), the sample loops from its end address back to its start address until it is stopped. Only the whole start-to-end range can loop; there is no separate loop point.

===Stopping a sample===
<syntaxhighlight lang="z80">
StopADPCMB:
ld de,(PB_CTRL1<<8)+$01 ;reset
call WritePortA
ld de,(PB_CTRL1<<8)+$00
call WritePortA
ret
</syntaxhighlight>

===End flag===
The ADPCM-B end flag is bit 7 of status 1 (port $06), and it is cleared through bit 7 of the flag control register $1C on port A, the same way as the ADPCM-A flags:

<syntaxhighlight lang="z80">
;Z flag clear on return if ADPCM-B has finished playing
CheckADPCMBEnd:
in a,($06) ;status 1
and $80
ret

ClearADPCMBEnd:
ld de,($1C<<8)+$80 ;clear and mask
call WritePortA
ld de,($1C<<8)+$00 ;unmask
call WritePortA
ret
</syntaxhighlight>

==ADPCM-A demo==

An interactive demo with source files can be found [http://smkdan.eludevisibility.org/neo/adpcma_demo2.zip here].

[[Category:Code]]
[[Category:Sound Code]]

Making scrollable backgrounds

2026-10-04T01:17:50Z

Furrtek: Unslop, note about possible methods

Scrolling backgrounds are formed by a set of [[sprites]] positioned directly next to each other. A full-size sprite is only 16 pixels wide, so 20 are needed to fill the [[frame_size|active display]] horizontally, with a 21st one used to fill the gap that would be present on an edge when scrolling by less than 16 pixels at a time. The [[sticky bit]] can be used to make this simpler and avoid the overhead of updating the position of so many sprites.

It is possible to take advantage of the 512 pixel wrapping property of sprite positions to set up a layer made of 32 sprites, and update the tiles of individual sprites just before they appear on screen. However all 32 sprites would count in the sprites-per-line limit of 96, which is very wasteful.

A better method is to "rotate" a set of 21 sprites and dynamically chaining and unchaining them.

==Demos==
Interactive demos with source can be found [http://smkdan.eludevisibility.org/neo/scroll_02.zip here].

(todo: clean it up, make scroll3, finish documenting it here)

[[Category:Code]]
[[Category:Graphics Code]]

Making scrollable backgrounds

2026-10-04T01:01:03Z

Furrtek: Reverted edits by Eaglesoftware777 (talk) to last revision by Freem

Scrolling backgrounds are formed using a set of [[sprites]] positioned directly next to each other. A sprite is only 16 pixels wide, so many are needed to fill the screen horizontally. The [[Sticky bit]] is often used to make this simpler. A set of 21 chained sprites can be used to make a single full-screen scrolling background layer.

==Updating VRAM==
(todo)

==Demos==
Interactive demos with source can be found [http://smkdan.eludevisibility.org/neo/scroll_02.zip here].

(todo: clean it up, make scroll3, finish documenting it here)

[[Category:Code]]
[[Category:Graphics Code]]

Development tools

2026-09-29T02:49:42Z

Furrtek: Reverted edits by Eaglesoftware777 (talk) to last revision by Defalt

__NOTOC__
==68000==
{|class="wikitable"
!colspan=6 style="background-color:#ccc"|Assemblers
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [http://john.ccac.rwth-aachen.de:8000/as/ AS] || Alfred Arnold, et al || Multi-target assembler || (multiple) || Provided as source code and binaries (Windows, DOS) ||  
|-
| [http://sun.hasenbraten.de/vasm/ vasm] || Volker Barthelmann, et al || Multi-target assembler || (multiple) || Provided as source code<br/>"official" binaries are for older versions ||  
|-
| JAS || Charles Doty, Paul Lee, Michael Hope || Modified version of AS || Windows || (base AS version unknown; binary is circa 1999/12/30) || [[File:JAS.zip]]
|-
| Maccer || Michael Hope || Pre-processor for AS-series assemblers || (multiple) || Provided as source code and Windows binary ||  
|-
| [http://gendev.spritesmind.net/page-macX.html MaccerX] || Kaneda || Updated version of Maccer || (multiple) || Provided as source code and Windows binary; added support for XGCC (gcc) and comments ||  
|-
| SNASM68K || S.N. Systems || 680x0 assembler || Windows ||   || [http://segaretro.org/SNASM68K SNASM68K at Sega Retro]<br/><small>(Modified version by Nemesis)</small>
|-
!colspan=6 style="background-color:#ccc"|Compilers
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| NeoDev kit || Fabrice Martinez, Jeff Kurtz, et al || GCC compiler and library || (multiple) ||   || [[File:NeoDev001.zip]]
|-
!colspan=6 style="background-color:#ccc"|Disassemblers
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| IRA || Tim Ruehsen, ported by Antirad || Intelligent ReAssembler for M680x0 || (multiple) || PC port of an Amiga app; provided as source ("PC") and binary (Windows) || [[File:Ira.zip]]
|-
| unidasm || MAMEdev || Universal Disassembler || (multiple) || Included with the Windows MAME distribution; can be built from source ||  
|}

==Z80==
{|class="wikitable"
!colspan=6 style="background-color:#ccc"|Assemblers
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [http://john.ccac.rwth-aachen.de:8000/as/ AS] || Alfred Arnold, et al || Multi-target assembler || (multiple) || Provided as source code and binaries (Windows, DOS) ||  
|-
| [http://sun.hasenbraten.de/vasm/ vasm] || Volker Barthelmann, et al || Multi-target assembler || (multiple) || Provided as source code<br/>"official" binaries are for older versions ||  
|-
| [https://github.com/vhelin/wla-dx WLA DX] || Ville Helin, et al || Multi-target assembler || (multiple) || Provided as source code || [http://www.niksula.cs.hut.fi/~tursas/wla/wladx_binaries_20040822.zip WLA-DX 9.2 Win32 binaries]
|-
| [http://www.nongnu.org/z80asm/ z80asm] || Bas Wijnen (and others?) || Z80 assembler || (multiple) || Provided as source code ||  
|-
!colspan=6 style="background-color:#ccc"|Compilers
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| ZCC || Ken Yap, et al || Z80 development package with C compiler || (multiple) || Provided as source code and binaries (Windows); circa January 1996 || [[File:zcc096.zip]]
|-
| [http://sdcc.sourceforge.net/ SDCC] || Sandeep Dutta, et al || "Small Device C Compiler" || (multiple) || Provided as source code and binaries (various platforms) || [http://sdcc.sourceforge.net/snap.php Snapshot Builds]
|-
| [http://www.z88dk.org/forum/ z88dk] || (many people) || z80 C cross compiler with assembler/linker || (multiple) || Provided as source code and binaries (Windows, Mac) || [http://nightly.z88dk.org/?C=M;O=D Nightly Builds]<br/><small>(Hit escape as soon as you see the links for "latest")</small>
|-
!colspan=6 style="background-color:#ccc"|Disassemblers
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| DASM || Charles Doty || Z80 disassembler || DOS || Source code and binary included. || [[File:dasmz80.zip]]
|-
| [http://www.inkland.org.uk/dz80/ DZ80] || Inkland || Z80 disassembler || (multiple) || Provided as source code (command line version) and binaries (DOS command line, Windows GUI) ||  
|-
| unidasm || MAMEdev || Universal Disassembler || (multiple) || Included with the Windows MAME distribution; can be built from source ||  
|-
| Z80DASM || ? || Z80 disassembler || Windows || Binary || http://trd.speccy.cz/sbor/Z80DASM.ZIP
|}

==Source Editors==
There are a lot of source code editors out there... Use whatever you're comfortable with (hopefully one with 68000 and Z80 syntax highlighting).

==Sound and Music==
{|class="wikitable"
|-
!colspan=6 style="background-color:#ccc"|Music Drivers and Tools
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [[MVSTracker]] || Ivan Mackintosh || FM tracker || Windows || [http://www.archaic.fr/interviews/interview-jeff-kurtz-repond-a-nos-questions/3/ Z80 driver does not work on hardware] ||  
|-
| [http://gendev.spritesmind.net/page-mvst.html MVSTracker Suite] || Pascal Bosquet, Kaneda || Modified version of MVSTracker || Windows || supports Mega Drive as well. Neo-Geo driver still doesn't work on hardware. ||  
|-
!colspan=6 style="background-color:#ccc"|Sound Editors
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [http://www.goldwave.com/release.php GoldWave] || GoldWave Inc. || commercial sound editor || Windows ||   ||  
|-
| [http://www.sonycreativesoftware.com/soundforgesoftware Sound Forge] || Sony || commercial sound editor || Windows, Mac ||   ||  
|-
| [http://audacity.sourceforge.net/ Audacity] || Audacity developers || open-source sound editor || (multiple) ||   ||  
|-
!colspan=6 style="background-color:#ccc"|Sound Encoders
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [https://github.com/freem/adpcma ADPCM-A encoder] || freem || Command-line ADPCM-A encoder || (multiple) || Provided as source code and binary (Windows) ||  
|-
| [http://www.smspower.org/forums/11965-VGMLoggingWithOtherEmulators?start=200#66597 ADPCM-B encoder] || ValleyBell and Fred/FRONT || Command-line ADPCM-B encoder || (multiple) || Provided as source code and binary (Windows) || [[File:ADPCM_Encode.zip]]
|-
| [[Neo Sound Builder]] || Jeff Kurtz/Neobitz || GUI V ROM/PCM file creator || Windows || ADPCM-A only || [https://www.facebook.com/Neobitz/photos/a.462349983789893.110879.221161891242038/1093044660720419/?type=3 announcement post]
|}

==Graphics==
{|class="wikitable"
|-
!colspan=6 style="background-color:#ccc"|Graphics Viewers and Editors
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [[YY-CHR]] || YY || multi-format tile editor || Windows || FIX files require plugin (YY-CHR.NET only, see below); Sprites need conversion (see tools below) || [http://www.romhacking.net/utils/119/ YY-CHR 0.99]
|-
| NGFX || blastar || Fix, Sprite, TITLE_*.SYS viewer/editor; LOGO_*.SYS viewer || Windows || WIP; not yet released. || [https://www.romhacking.net/download/utilities/1175/]
|-
| neospriteviewer || Matt Greer || S and C ROM tile viewer || Web ||   || [https://neospriteviewer.mattgreer.dev site]
|-
!colspan=6 style="background-color:#ccc"|Graphics Converters and Tools
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| [[DATLib]] graphics tools || HPMAN || Tools used to process and display graphics on Neo-Geo. || Windows || Animator, BuildChar, CharSplit, Framer || [https://www.dropbox.com/s/wqviye5xxzktr6y/DATlib_0.3.rar?dl=0 download]
|-
| [[NGGTool|NeoGeo Graphics ToolSuite]] || evo || Tool to convert between SNES/SFC and Neo-Geo graphics. || Windows || Fix conversion is botched (see page for details) || [http://furrtek.free.fr/noclass/neogeo/nggts.zip NGGTS]
|-
| Sprite graphics converter || IQ || Converts MVS graphics (.c*) to CD graphics (.SPR). || Windows ||   || [http://furrtek.free.fr/noclass/neogeo/gfxmvstocd.zip MVS to CD sprite converter]
|-
| [https://github.com/freem/NeoSpriteConv Neo-Geo Sprite Converter] || freem || Convert 4BPP SMS/GG/WSC graphics to Neo-Geo format. || (multiple) || Provided as source code and binary (Windows)<br/><small>Further work required for converting to Cart (split files by words (2 bytes)) and CD (byteswap file)-usable files.</small> || [http://ajworld.net/neogeodev/utils/neosprconv.zip main download]
|-
| [https://github.com/Kannagi/Neoconvert Neoconvert] || Kannagi || Convert PNG to rom Cx with map, palette and HiColor. || Windows,Linux || || [https://github.com/Kannagi/Neoconvert download]
|-
| [https://github.com/Kannagi/Neoextract Neoextract] || Kannagi || extract rom Cx or s1 to bmp. || Windows,Linux || || [https://github.com/Kannagi/Neoextract download]
|
|-
| [https://github.com/city41/sromcrom sromcrom] || Matt Greer || Generate S and C ROMs from images, generates corresponding source code as well || cross platform || || [https://github.com/city41/sromcrom download]
|
|-
| [https://neo-source.com/index.php?topic=4180.msg37936 buildobj] || iq_132 || Compress / Decompress NeoGeo CD OBJ files || Windows || || [https://neo-source.com/index.php?topic=4180.msg37936 buildobj]
|}

==Other Tools==
{|class="wikitable"
|-
!Name !! Author(s) !! Description !! Platform(s) !! Notes !! Download
|-
| MemCardTool || Fabrice Martinez || Memory card manager || Windows ||   || [[File:memcardtool.zip]]
|-
| [https://github.com/freem/romwak ROMwak] || Jeff Kurtz, ported by freem || Binary image manipulation tool || (multiple) || Provided as source code and binary (Windows) ||  
|}

[[Category:Code]]

User talk:Eaglesoftware777

2026-09-28T15:36:35Z

Furrtek:

'''Welcome to ''NeoGeo Development Wiki''!'''
We hope you will contribute much and well.
You will probably want to read the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents help pages].
Again, welcome and have fun! [[User:Furrtek|Furrtek]] ([[User talk:Furrtek|talk]]) 11:42, 23 September 2026 (CEST)

Hello. I need to know if your edits are AI-generated, and/or if you allow AI agents to make edits on your behalf through your account.

USER subroutine

2026-09-27T00:58:54Z

Furrtek: /* Command 2 */

The USER subroutine (not called, always jumped to by the [[system ROM]]) is required [[68k]] code which needs to perform actions according to the command value set in {{BR|BIOS_USER_REQUEST}}.

At the end of the routine, a jump to [[SYSTEM_RETURN|BIOSF_SYSTEM_RETURN]] is needed to give back control to the BIOS.

=Handling code=

<syntaxhighlight>
JT_User:
dc.l StartupInit
dc.l EyeCatcher
dc.l Game
dc.l Title

User:
move.b d0,REG_DIPSW
clr.l d0
move.b BIOS_USER_REQUEST,d0
lsl.b #2,d0
lea JT_User,a0
movea.l (a0,d0),a0
jsr (a0)
jmp BIOSF_SYSTEM_RETURN
</syntaxhighlight>

=USER_REQUEST values=

==Command 0==
Initialize the backup RAM data (default highscores, rankings, etc).

On MVS, requested only once when the game is started for the first time on the system (the [[system ROM]] doesn't find the game's NGH number in the [[backup RAM]]).
On AES, always requested on startup.

Set {{BR|BIOS_USER_MODE}} to 0 during operations, and don't forget to kick the watchdog as interrupts are disabled.

[[Viewpoint]], which has its backup RAM save pointer set to $100000 ([[68k program header]] $10E) and game save size set to $0200 (header $112) does this:
<syntaxhighlight>
move.b #$00,BIOS_USER_MODE
lea $100000,a0 ; Start of game save block
move #$001F,d1 ; 32*4 longword writes = 512 bytes
moveq #0,d0
.cl:
move.l d0,(a0)+
move.l d0,(a0)+
move.l d0,(a0)+
move.l d0,(a0)+
dbf d1,.cl
move.b d0,REG_WATCHDOG
...
jmp BIOSF_SYSTEM_RETURN
</syntaxhighlight>

Exit by jumping to SYSTEM_RETURN.

==Command 1==
Show the game's own boot logo animation (when [[68k program header|$114]] = 1).

This command by default is only called on AES and not on the [[MVS]]. It is called once only at system start (before attract mode) and not again.

Later games by SNK trick the MVS bios into calling this subroutine. They do this by first moving and then executing code from RAM during their command 2 routine. This code determines the games SLOT location and then stores this location to address 0xD00058 (See routine from 0xA910E in KOF99).

A side affect is the new eye catcher does not display right away, at least one attract mode sequence must be completed first. SNK appear to have done this with the aim of updating the original spinning logo with their new version and thus this method is not advised if you want an eye catcher to show on MVS hardware. Instead it is advised to call your own the eye catcher routine from within command 2 (attract mode) only. See Aero Fighters 2 as an example, it has both the Neo Geo eye catcher and a VideoSystem eye catcher.

==Command 2==
Show the game's demo, this means anything related to attract mode. (the recommended duration is ?). Jump to SYSTEM_RETURN if the game wasn't started, or after a game over.

On AES systems the system ROM only comes this far and never proceeds further.

==Command 3==
Show the game's title screen. This is called when a coin is inserted on [[MVS]] only and is never called on AES systems. {{BR|BIOS_COMPULSION_TIMER}} is used as a count-down timer for auto-start.

Some games write 0x01 to 0x10FEC5 in this routine. It stops the bios calling command 3 twice after game over if credits are already in the system (attract mode skipped). When 0x00 the bios will initiate another command 3 a few frames after the first. This causes the title page to draw twice. This could be a bios bug which SNK fixed by adding this variable in a later bios revision (needs confirming).

To see an example compare Art or Fighting to Art of Fighting 2 after game over.

[[Category:Code]]

USER subroutine

2026-09-27T00:53:40Z

Furrtek: /* Command 0 */

The USER subroutine (not called, always jumped to by the [[system ROM]]) is required [[68k]] code which needs to perform actions according to the command value set in {{BR|BIOS_USER_REQUEST}}.

At the end of the routine, a jump to [[SYSTEM_RETURN|BIOSF_SYSTEM_RETURN]] is needed to give back control to the BIOS.

=Handling code=

<syntaxhighlight>
JT_User:
dc.l StartupInit
dc.l EyeCatcher
dc.l Game
dc.l Title

User:
move.b d0,REG_DIPSW
clr.l d0
move.b BIOS_USER_REQUEST,d0
lsl.b #2,d0
lea JT_User,a0
movea.l (a0,d0),a0
jsr (a0)
jmp BIOSF_SYSTEM_RETURN
</syntaxhighlight>

=USER_REQUEST values=

==Command 0==
Initialize the backup RAM data (default highscores, rankings, etc).

On MVS, requested only once when the game is started for the first time on the system (the [[system ROM]] doesn't find the game's NGH number in the [[backup RAM]]).
On AES, always requested on startup.

Set {{BR|BIOS_USER_MODE}} to 0 during operations, and don't forget to kick the watchdog as interrupts are disabled.

[[Viewpoint]], which has its backup RAM save pointer set to $100000 ([[68k program header]] $10E) and game save size set to $0200 (header $112) does this:
<syntaxhighlight>
move.b #$00,BIOS_USER_MODE
lea $100000,a0 ; Start of game save block
move #$001F,d1 ; 32*4 longword writes = 512 bytes
moveq #0,d0
.cl:
move.l d0,(a0)+
move.l d0,(a0)+
move.l d0,(a0)+
move.l d0,(a0)+
dbf d1,.cl
move.b d0,REG_WATCHDOG
...
jmp BIOSF_SYSTEM_RETURN
</syntaxhighlight>

Exit by jumping to SYSTEM_RETURN.

==Command 1==
Show the game's own boot logo animation (when [[68k program header|$114]] = 1).

This command by default is only called on AES and not on the [[MVS]]. It is called once only at system start (before attract mode) and not again.

Later games by SNK trick the MVS bios into calling this subroutine. They do this by first moving and then executing code from RAM during their command 2 routine. This code determines the games SLOT location and then stores this location to address 0xD00058 (See routine from 0xA910E in KOF99).

A side affect is the new eye catcher does not display right away, at least one attract mode sequence must be completed first. SNK appear to have done this with the aim of updating the original spinning logo with their new version and thus this method is not advised if you want an eye catcher to show on MVS hardware. Instead it is advised to call your own the eye catcher routine from within command 2 (attract mode) only. See Aero Fighters 2 as an example, it has both the Neo Geo eye catcher and a VideoSystem eye catcher.

==Command 2==
Show the game's demo, this means anything related to attract mode. (the recommended duration is ?).

On AES systems the bios only comes this far and never calls command 3, if title page is required it must be done here.

==Command 3==
Show the game's title screen. This is called when a coin is inserted on [[MVS]] only and is never called on AES systems. {{BR|BIOS_COMPULSION_TIMER}} is used as a count-down timer for auto-start.

Some games write 0x01 to 0x10FEC5 in this routine. It stops the bios calling command 3 twice after game over if credits are already in the system (attract mode skipped). When 0x00 the bios will initiate another command 3 a few frames after the first. This causes the title page to draw twice. This could be a bios bug which SNK fixed by adding this variable in a later bios revision (needs confirming).

To see an example compare Art or Fighting to Art of Fighting 2 after game over.

[[Category:Code]]

System self-test

2026-09-26T23:57:27Z

Furrtek:

Memory tests are done by writing and reading back 55, AA and incrementing values.

Some information by Channelmaniac.

{|class="regdef"
|'''Error'''
|No game
|[[WORK RAM ERROR]]
|[[COLOR RAM ERROR]]
|[[VIDEO RAM ERROR]]
|[[SYSTEM ROM ERROR]]
|[[MEMORY CARD ERROR]]
|-
|'''AES'''
|[[File:aes_sc_blue.png]]
|[[File:aes_sc_red.png]]
|[[File:aes_sc_green.png]]
|[[File:aes_sc_yellow.png]]
|[[File:aes_sc_pink.png]]
|[[File:aes_sc_cyan.png]]
|-
|'''MVS'''
|[[File:crosshatch.png|160px]] [[Crosshatch]]
|[[File:error_wram.png|160px]]
|[[File:error_color0.png|160px]]
|[[File:error_vram.png|160px]]
|[[File:error_sysrom.png|160px]]
|Screenshot needed
|-
|'''Meaning'''
|All tests passed (AES does not test the {{Chipname|Z80}}). Cartridge not detected.
|[[68k user RAM]] R/W error
|[[Palette RAM]] R/W error
|[[VRAM]] R/W error
|[[system ROM error|System ROM checksum mismatch]]
|[[Memory card]] R/W error (only tested if card present and blank)
|}

=AES=
The AES only performs checks when no game is detected. They're done in the following order:
# [[68k user RAM]]
# [[Palette RAM]] bank 0
# Palette RAM bank 1
# Lower [[VRAM]]
# Upper VRAM
# [[System ROM]] checksum

==MVS==

Additionnal checks are performed on MVS systems. The SP-S2 [[system ROM]] does them in the following order:

# [[68k user RAM]]
# Backup RAM
# [[Palette RAM]] bank 0
# Palette RAM bank 1
# Lower [[VRAM]]
# Upper VRAM
# [[RTC]]
# [[System ROM]] checksum
# [[Z80]]

{|class="regdef"
|'''Error'''
|[[BACKUP RAM ERROR]]
|[[Calendar freeze]]
|[[CALENDAR ERROR]]
|[[Z80 ERROR]]
|-
|'''Display'''
|[[File:error_bram.png|160px]]
|[[File:calendar_freeze.png|160px]]
|[[File:error_calendar.png|160px]]
|[[File:error_z80.png|160px]]
|-
|'''Meaning'''
|[[Backup RAM]] R/W error
|[[RTC]] isn't giving Time Pulse
|[[RTC]] ran to slow or too fast
|[[Z80]] didn't reply to command
|}

When a MVS board is powered up without cartridges inserted, the border color around the edges of the crosshatch screen indicates the system ROM region:

* Red: Japanese, SPJ2
* Cyan: USA, SPU2
* Blue: Korean/Spanish, SPS2
* Yellow: European
* Green: 6 slot (ROM name ?)

=UniBios tests=

The [[Universe BIOS]] does not use the above color codes to indicate errors.

[[Category:Base system]]
[[Category:Repairs]]

NEO-PCM2

2026-09-26T17:50:43Z

Furrtek: /* SNK version */

{{ChipInfo
|picture=brd_pcm2.jpg
|pkg=QFP120
|manu=fujitsu
|date=1999, 2002
|gates=
|used_on=[[Cartridges]], [[ROM-Only boards]]
}}

Second version of {{Chipname|PCM}} which confusingly exists in two forms under the same name. [[V ROM]] demultiplexer, decryption and [[P ROM]] banking chip.

The demultiplexing logic is exactly the same as the one found in PCM.

=Jumpers=

The ROM and mapping configuration for a given game is set by external jumpers. There are 3 for the V ROMs (JV1 to JV3) and 4 for the P ROMs (J1 to J4).
These do not appear to affect security functions.

V ROM mapping uses address bits 20 to 23. There are 4 chip select outputs.

=Security=

The security function of the 1999 SNK branded version only performs address descrambling on V ROMs. The Playmore version which came out in 2002 adds a data decryption layer on top, which means both are not interchangeable.

The decryption algorithm used by emulators currently isn't perfectly exact, which explains the presence of a few corrupt bytes in decrypted romsets causing minor audio glitches (Samurai Shodown V "Basara" sample).

==SNK version==

P ROM bank selection is done by writing the 3 lower bits of the [[68k memory map|port zone]] with A19 high to not affect the V ROM setting. ie. $280000 (word) or $280001 (even) with mirrors up to $2FFFFF.
Metal Slug 4 for example writes words to $2FFFF0. Todo: how does the bank number map to an address.

V ROM address scrambling is only done on the 4 lower bits by selectively inverting them depending on the configuration set by the [[68k]] CPU. Bits 4 to 23 go straight through.

This is set by first writing 7 to the [[68k memory map|port zone]], the same way P bank 7 would be selected. And then writing the 3 bit configuration value with A19 low.
Metal Slug 4 for example writes words on startup to the bogus addresses $200000, $208000 and $220000.

To test:
{| class="wikitable"
|-
! V configuration !! VA3 !! VA2 !! VA1 !! VA0
|-
| 0 || invert || invert || invert || invert
|-
| 1 || invert || invert || normal || invert
|-
| 2 || normal || invert || invert || invert
|-
| 3 || invert || invert || normal || invert
|-
| 4 || invert || invert || invert || invert
|-
| 5 || invert || invert || normal || normal
|-
| 6 || invert || normal || invert || invert
|-
| 7 || invert || invert || normal || invert
|}

==Playmore version==

Todo.

=Games=

Used by:
* [[Matrimelee]] (Playmore)
* [[Metal Slug 4]] (SNK)
* [[Metal Slug 5]] (Playmore)
* [[Pochi and Nyaa]] (SNK)
* [[Rage of the Dragons]] (SNK)
* [[Samurai Shodown V]] (Playmore)
* [[Samurai Shodown V Special]] (Playmore)
* [[SNK vs. Capcom - SVC Chaos]] (Playmore)
* [[The King of Fighters 2001]] (SNK)
* [[The King of Fighters 2002]] (Playmore)
* [[The King of Fighters 2003]] (Playmore)

=Pinout=

[[File:Neo-pcm2_pinout.png|800px]]

OpenOffice Draw file: [[File:neo-pcm2.odg]]

Does the Playmore version have the same pinout ?

[[Category:Chips]]

User talk:RetroArcadeTech

2026-09-23T09:42:42Z

Furrtek: Welcome!

User talk:NeoGeoChronicler

2026-09-23T09:42:38Z

Furrtek: Welcome!

User talk:Eaglesoftware777

2026-09-23T09:42:10Z

Furrtek: Welcome!

Furrtek: Furrtek uploaded a new version of File:NEO-244 pinout.png

NEO-253

2026-08-15T23:58:11Z

Furrtek: /* Pinout */

{{ChipInfo
|picture=Neo-253.jpg
|pkg=QFP64R
|manu=fujitsu
|date=1992 ?
|gates=
|used_on={{PCB|SLOT4F}}
}}

Quintuple 74HC253 4-to-1 multiplexers with common select lines, making ten 4-to-1 switches in one chip. Used to switch read-only buses. The inputs are named according to the related slot: A is slot #1, B is slot #2...

Only (?) used on second revision 4-slot MVS systems. Not to be confused with the more common {{Chipname|NEO-273}}.

=Pinout=

[[File:Neo-253_pinout.png|512px]]

Select signals come from {{Chipname|NEO-F0}} SLOTA and SLOTB.

==SLOT4F @ 5E==

Cartridge [[wait cycle]] configuration and [[Z80]] bus.

*Mux 1: PWAIT0
*Mux 2: PWAIT1
*Mux 10~3: SDD7~SDD0

Outputs go to CN9.

==SLOT4F @ 5D==

[[Sprites]] and [[fix layer]] graphics.

*Mux 1: CR30
*Mux 2: CR31
*Mux 10~3: FIXD7~FIXD0

==SLOT4F @ 5C==

Sprite graphics.

*Mux 10~1: CR29~CR20

==SLOT4F @ 5B==

Sprite graphics.

*Mux 10~1: CR19~CR10

==SLOT4F @ 5A==

Sprite graphics.

*Mux 10~1: CR9~CR0

[[Category:Chips]]

2026-08-15T14:50:20Z

Furrtek:

<span style="background: #ADD; padding:2px; font-size:8pt;">'''[[BIOS_RAM_locations#{{{1}}}|{{{1}}}]] '''
({{ #ifeq: {{{1|}}} | BIOS_GAME_DIP | $10FD84+}}{{ #ifeq: {{{1|}}} | BIOS_USER_REQUEST | $10FDAE}}{{ #ifeq: {{{1|}}} | BIOS_USER_MODE | $10FDAF}}{{ #ifeq: {{{1|}}} | BIOS_UPSRC | $10FEF8}}{{ #ifeq: {{{1|}}} | BIOS_UPDEST | $10FEF4}}{{ #ifeq: {{{1|}}} | BIOS_UPSIZE | $10FEFC}}{{ #ifeq: {{{1|}}} | BIOS_UPZONE | $10FEDA}}{{ #ifeq: {{{1|}}} | BIOS_UPBANK | $10FEDB}}{{ #ifeq: {{{1|}}} | BIOS_DEVMODE | $10FE80}}{{ #ifeq: {{{1|}}} | BIOS_COMPULSION_TIMER | $10FDDA}}
{{ #ifeq: {{{1|}}} | BIOS_GAME_DIP | $10FD84}}{{ #ifeq: {{{1|}}} | BIOS_CREDIT_DEC1 | $10FDB0}}{{ #ifeq: {{{1|}}} | BIOS_CREDIT_DEC2 | $10FDB1}}{{ #ifeq: {{{1|}}} | BIOS_START_FLAG | $10FDB4}}{{ #ifeq: {{{1|}}} | BIOS_PLAYER_MOD | $10FDB6}}{{ #ifeq: {{{1|}}} | BIOS_P1STATUS | $10FD94}}{{ #ifeq: {{{1|}}} | BIOS_MONTH | $10FDD3}}{{ #ifeq: {{{1|}}} | BIOS_MVS_FLAG | $10FD82}})</span>