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[[Category:Hardware]] | [[Category:Hardware]] | ||
[[Category:Sound]] | |||
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. | ||
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. | ||
On Spectrum-based machines, the AY chip is normally clocked at half the CPU clock. Melodik, the [[Timex | On Spectrum-based machines, the AY chip is normally clocked at half the CPU clock. Melodik, the [[Timex 2000 series|TC2068]] and the Pentagon have an AY clocked at 1.75 Mhz. The [[Timex 2000 series|TS2068]]'s AY chip is clocked at 1.764 MHz. The Timex machines use different ports to the 128K. | ||
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. | ||
The AY-3-8910 has 16 registers: | The AY-3-8910 has 16 registers: | ||
{| border=1 cellpadding=1 | |||
|Register||Purpose||Width||Notes | |||
|- | |||
|0||Channel A fine pitch||'''8''' bits | |||
|- | |||
|1||Channel A coarse pitch||'''4''' bits | |||
|- | |||
|2||Channel B fine pitch||'''8''' bits | |||
|- | |||
|3||Channel B coarse pitch||'''4''' bits | |||
|- | |||
|4||Channel C fine pitch||'''8''' bits | |||
|- | |||
|5||Channel C coarse pitch||'''4''' bits | |||
|- | |||
|6||Noise pitch||'''5''' bits | |||
|- | |||
|7||Mixer||'''8''' bits | |||
|- | |||
|8||Channel A volume||'''4''' bits | |||
|- | |||
|9||Channel B volume||'''4''' bits | |||
|- | |||
|10||Channel C volume||'''4''' bits | |||
|- | |||
|11||Envelope fine duration||'''8''' bits | |||
|- | |||
|12||Envelope coarse duration||'''8''' bits | |||
|- | |||
|13||Envelope shape||'''4''' bits | |||
|- | |||
|14||I/O port A||'''8''' bits | |||
|- | |||
|15||I/O port B||'''8''' bits||(not used by AY-3-8912) | |||
|} | |||
== External links == | == External links == | ||
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* [[wikipedia:AY-3-8912|Wikipedia page]] | * [[wikipedia:AY-3-8912|Wikipedia page]] | ||
* http://www.armory.com/~rstevew/Public/SoundSynth/Novelty/AY3-8910/start.html | * http://www.armory.com/~rstevew/Public/SoundSynth/Novelty/AY3-8910/start.html | ||
{{CC-BY-SA-techwiki|AY-3-8912(a)|AY-3-8912%28a%29}} | {{CC-BY-SA-techwiki|AY-3-8912(a)|AY-3-8912%28a%29}} |
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