PCM: Difference between revisions

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[[File:crt_pcm.jpg|right|thumb|NEO-PCM chip found in a MVS cartridge. Picture courtesy of [[http://www.mvs-scans.com MVS-Scans]].]]
[[File:crt_pcm.jpg|right|thumb|NEO-PCM chip found in a MVS cartridge. Picture courtesy of [[http://www.mvs-scans.com MVS-Scans]].]]


[[V ROM]] banking and multiplexing chip, found in AES and MVS [[cartridges]].
[[V ROM]] banking and multiplexing chip, found in AES and MVS [[cartridges]], and on [[ROM-Only boards|ROM-only]] arcade boards. Used to multiplex V ROM (ADPCM-A and ADPCM-B) access to mixed-content ROM chips.


[[NEO-PCM2]] can also be found in late cartridges and with [[NEO-YSA2]] on [[ROM-Only boards|ROM-only]] arcade boards.
[[NEO-PCM2]] can also be found in late cartridges and with [[NEO-YSA2]].


On some [[cartridge boards]], V A20~V A22 can be used to select which of the 4 possible V ROMs to use (decoded by a LS139).
On some [[cartridge board]]s, V A20~V A22 can be used to select which of the 4 possible V ROMs to use (decoded by a LS139).


=Pinout=
=Pinout=
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OpenOffice Draw file: [[File:pcm.odg]]
OpenOffice Draw file: [[File:pcm.odg]]


Pin 47 is GND.
Has an inverting gate on pins 26 and 27.
Not sure about A19.
 
*SDPOE, SDROE, SDPMPX, SDRMPX: from the [[YM2610]]
*SDPOE, SDROE, SDPMPX, SDRMPX: from the [[YM2610]]


*SDRAD0~SDRAD7: ADPCM-A data bus
*SDRAD0~SDRAD7: ADPCM-A multiplexed bus part
*SDPAD0~SDPAD7: ADPCM-B data bus
*SDPAD0~SDPAD7: ADPCM-B multiplexed bus part


*SDRA8,SDRA9,SDRA20~SDRA23: ADPCM-A address bus
*SDRA8,SDRA9,SDRA20~SDRA23: ADPCM-A address bus
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*V D0~V D7: V ROM(s) data bus
*V D0~V D7: V ROM(s) data bus
*V A0~V A21: V ROM(s) address bus
*V A0~V A22: V ROM(s) address bus


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

Revision as of 21:09, 6 April 2012

NEO-PCM chip found in a MVS cartridge. Picture courtesy of [MVS-Scans].

V ROM banking and multiplexing chip, found in AES and MVS cartridges, and on ROM-only arcade boards. Used to multiplex V ROM (ADPCM-A and ADPCM-B) access to mixed-content ROM chips.

NEO-PCM2 can also be found in late cartridges and with NEO-YSA2.

On some cartridge boards, V A20~V A22 can be used to select which of the 4 possible V ROMs to use (decoded by a LS139).

Pinout

File:Pcm pinout.png

OpenOffice Draw file: File:Pcm.odg

Has an inverting gate on pins 26 and 27.

  • SDPOE, SDROE, SDPMPX, SDRMPX: from the YM2610
  • SDRAD0~SDRAD7: ADPCM-A multiplexed bus part
  • SDPAD0~SDPAD7: ADPCM-B multiplexed bus part
  • SDRA8,SDRA9,SDRA20~SDRA23: ADPCM-A address bus
  • SDPA8~SDPA11: ADPCM-B address bus
  • V D0~V D7: V ROM(s) data bus
  • V A0~V A22: V ROM(s) address bus