Category:PSG
This page was last modified 14:23, 8 June 2021 by Gdx. Based on work by Mars2000you.

Description

The standard 40-pin sound chip in the MSX is called the PSG (Programmable Sound Generator). It can play either a tone or noise on each of its three voices. It also controls the Joystick ports and a few other things.

Like other parts of the MSX specification, the PSG chip was an off-the-shelf part. In this case the General Instrument AY-3-8910, which can also be found in many other systems of the era. This chip, or one of its clones, can be found in many MSX1 systems. In newer MSX systems, the PSG is often integrated in a chip called the MSX-Engine (or MSX-System).

Note: Yamaha uses the SSG (Software-controlled Sound Generator) appellation in its technical documentations but it is PSG that is used in the MSX standard documentations.

List of fully compatible chips:

Note: The Yamaha YM2149 is called SSG (Software-controlled Sound Generator).

Software compatible chips:

  • General Instrument AY-3-8912 (One I/O port only)
  • Yamaha YMZ294 (No I/O port)

Note: Some cartridges add or emulate a second PSG. In this case, it needs to be viewed as a Music Expansion.

Software that uses the PSG for BGM and/or SFX.

Stereo

The General Instrument AY-3-8910 outputs the three channels separately, and so do the Yamaha YM2149 and the PSGs integrated in the Toshiba T7937 and Toshiba T9769 MSX-ENGINEs. The Yamaha S3527 MSX-SYSTEM integrated PSG is down-mixed to a single mono channel. The Yamaha S1985 MSX-SYSTEMII mixes the channels into a left and right channel (A: Center, B: Left, C: Right).

Most MSX computers output mono, however some machines pan the channels to center, left and right. On the Toshiba machines the left and right channel are swapped. Daewoo established yet another panning. Below is a table of MSX models with stereo output and the panning of the respective channels.

Model Channel A Channel B Channel C Notes
Daewoo CPC-400 Left Right Right Stereo / mono switch on the back
Daewoo CPC-400S Left Right Right Stereo / mono switch on the back
National FS-5000 Center Left Right Stereo / mono switch on the back
Pioneer PX-7 Center Left Right
Pioneer PX-7(HB) Center Left Right
Pioneer PX-V7 Center Left Right
Toshiba HX-20 * Center Right Left Stereo / mono switch on the back
Toshiba HX-21 * Center Right Left Stereo / mono switch on the back
Toshiba HX-22 * Center Right Left Stereo / mono switch on the back
Toshiba HX-23 Center Right Left Stereo / mono switch on the back
Toshiba HX-23F Center Right Left Stereo / mono switch on the back
Toshiba HX-32 Center Right Left Stereo / mono switch on the back
Toshiba HX-33 Center Right Left Stereo / mono switch on the back
Toshiba HX-34 Center Right Left Stereo / mono switch on the back

* = only the Japanese model

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