NEO-MGA: Difference between revisions

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[[File:cd2_mga.jpg|right|thumb|NEO-MGA-T chip found on a CDM3-2 board.]]
{{ChipInfo
|picture=cd1_neo-mga.jpg
|pkg=QFP160
|manu=fujitsu
|date=1994 ?
|gates=?
|used_on={{PCB|CDROM-2 board|CDROM-2}}, {{PCB|MV1A}}...
}}


The NEO-MGA-T is a damn chip nobody knows about, which is found in the CD1 and CD2 versions of the NeoGeo hardware.
Multi-purpose chip found in CD systems and some late MVS boards:
The CD-Z has a NEO-MGA-T2, probably to handle the faster CD reading speeds and new copy protection system.
* NEO-MGA in the CD1 model (front loading).
The front loading NeoGeo CD has a NEO-MGA chip.
* {{Chipname|NEO-MGA-T}} in the CD2 model (top loading) and {{PCB|MV1A}} MVS boards, can be swapped with NEO-MGA.
* {{Chipname|NEO-MGA2-SA}} in the [[CDZ]], replaces the {{Chipname|LC8953}} ?


It's in charge of the communication with the CD drive, data transfers to the [[LC89515]] host and buffering CDDA data for the [[BIOSes]] vu-meters.
It is used for address decoding, communication with the [[CD drive]], for refreshing {{Chipname|68k}} [[DRAM]], and for buffering serial [[CDDA]] data.
 
=CD pinout=
 
Pin 93: GND !
 
[[File:Neo-mga_CD_pinout.png|700px]]
 
[[File:Neo-mga_cd.odg]]
 
=MV1A pinout=
 
[[File:Neo-mga_MV1A_pinout.png|700px]]
 
[[File:Neo-mga_mv1a.odg]]
 
=Signals=
 
* DRM*, RAS, CAS, WRITE: See TC514400 DRAM datasheet.
* X*: See [[LC8953]] datasheet.


[[Category:Chips]]
[[Category:Chips]]

Latest revision as of 23:22, 20 September 2022

File:Cd1 neo-mga.jpg
Package QFP160
Manufacturer
First use 1994 ?
Used on CDROM-2 board, MV1A...

Multi-purpose chip found in CD systems and some late MVS boards:

  • NEO-MGA in the CD1 model (front loading).
  • NEO-MGA-T in the CD2 model (top loading) and MV1A MVS boards, can be swapped with NEO-MGA.
  • NEO-MGA2-SA in the CDZ, replaces the LC8953 ?

It is used for address decoding, communication with the CD drive, for refreshing 68k DRAM, and for buffering serial CDDA data.

CD pinout

Pin 93: GND !

File:Neo-mga cd.odg

MV1A pinout

File:Neo-mga mv1a.odg

Signals

  • DRM*, RAS, CAS, WRITE: See TC514400 DRAM datasheet.
  • X*: See LC8953 datasheet.