General Instrument AY-3-8910

The AY- 3-8910 was in earlier home computers and game machines very often inserted sound and Multi-I/O-Chip, which was developed by General Instrument in the early 1980s. He was slightly changed as licensed to Yamaha YM2149 and from 1987 by Microchip, the outsourced microelectronics division of GI produced. The chip was in most of the early arcade games, but also in some home computers, so also in the Schneider / Amstrad CPC, ZX Spectrum 128K and Atari ST.

Technology

The main part of the chip was designed for sound and noise generation. These had the AY- 3-8910 three independent voices whose frequency was set at 1024 levels. The volume of each voice was adjustable in 16 steps each, in addition, there was a common envelope for all three votes. For each voice could be used to set whether the envelope should apply. Furthermore, there was a random number generator in the chip that could be interrogated by the processor, or to mixed to each voice as the noise source.

A special feature was that each part had its own output pin. Most of them were simply connected together outside the chip, also Dreikanalton or stereo plus a common voice for the right and left was basically so but possible.

The two each 8 -bit I / O ports could be connected as a group on each input or output. Since the port pins were connected as open collector, but also a mixture of inputs and outputs on a port was possible. For example conceivable was the connection of joysticks, fire and control buttons and a keyboard matrix.

The chip was designed for connection to a specific, used by in-house CPUs of the company GI bus. Since he was not usually connected together in practice this rarely-used processors, but eg with the Zilog Z80 and the MOS Technology 6502 and their variants, the bus had to be modeled, for example, using glue logic or an interface module, such as the MOS Technology VIA and additional software support.

Was made the block in various technologies / Packages. The standard version was a DIL -40 package. Later it was there even in smaller enclosures, now he is no longer being manufactured.

Predecessor

AY- 1-0212 (top- octave synthesizer chip )
AY- 3-214

Variants

AY- 3-8912 direct successor; 28 pins instead of 40, only 8 Bit-I/O-Port instead of two
AY- 3-8913 24 pins, slightly scaled-down version
AY- 3-8914 40 pins