AY-3-8912: Difference between revisions
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[[Category:Hardware]] | [[Category:Hardware]] | ||
[[Category:Audio]] | [[Category:Audio]] | ||
The '''AY-3-8912''' is a sound generator that is built-in on several 128 KB models of the [[ZX Spectrum]] and in the [[Timex 2000 series|Timex Sinclair 2068]], but can also be found in several peripherals, such as the Fuller Box an the Melodik interface. | The '''AY-3-8912''' is a sound generator that is built-in on several 128 KB models of the [[ZX Spectrum]] and in the [[Timex 2000 series|Timex Sinclair 2068]], but can also be found in several peripherals, such as the Fuller Box an the Melodik interface. On the 128 models, it can also provide MIDI and RS-232 connections. | ||
The 128K's AY chip is clocked at 1.7734 MHz (to within 0.01%). Writing to port FFFDh (65533) selects a register, and reading from port FFFDh reads that register's contents. Writing to port BFFDh (49149) writes new data to the currently selected register. On the 128K/+2, reading from BFFDh will return the [[floating bus]] value as normal for unattached ports, but on the +2A/+3, it will return the same as reading from FFFDh. The Melodik interface uses the same ports as the 128K. | The 128K's AY chip is clocked at 1.7734 MHz (to within 0.01%). Writing to port FFFDh (65533) selects a register, and reading from port FFFDh reads that register's contents. Writing to port BFFDh (49149) writes new data to the currently selected register. On the 128K/+2, reading from BFFDh will return the [[floating bus]] value as normal for unattached ports, but on the +2A/+3, it will return the same as reading from FFFDh. The Melodik interface uses the same ports as the 128K. | ||
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Various peripherals, such as the Fuller Box, use different ports to any other interface. The Fuller Box is nominally clocked at 1.75 Mhz but suffers from contention problems. | Various peripherals, such as the Fuller Box, use different ports to any other interface. The Fuller Box is nominally clocked at 1.75 Mhz but suffers from contention problems. | ||
== Register map == | |||
The AY-3-8910 has 16 registers: | The AY-3-8910 has 16 registers: | ||
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|15||I/O port B||8' bits||(not used by AY-3-8912) | |15||I/O port B||8' bits||(not used by AY-3-8912) | ||
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== MIDI and RS-232 == | |||
I/O port A of the 128K's AY chip is connected through to a combined MIDI and RS-232 port, for which an adaptor is required. Each port is bi-directional, with the serial interface supporting the RXD, TXD, RTS and CTS lines. | |||
== External links == | == External links == | ||