Williams compatible ATMEGA based soundboard
The main board
ATMEGA8 micro-controller, audio amp, voltage reg., 14.318MHz crysal, R2R array and test switch.
It's based on an Atmel ATMEGA microcontroller so hence the name "Megasound"
Comparison with an original board
The ATMEGA8 contains a simulator for the 6800, 6821 PIA,
6810 SRAM and the 4K of sounboard ROM.
- Could use almost any of the ATMega family of micro-controllers. A highly available and modern part.
System clocking is at 14.318MHz, which is exactly
4x the original clock, and 16x faster than the minimum cycle
for the MC6808/6802 CPU on the original.
The simulator was written in AVR assembler and all op-codes
are coded to be cycle identical to the original 6808/2.
The current output DAC is replaced by a R2R ladder nework array
on the Megasound board.
- LM380 audio amp was used for the demo board. That will probably
change to a TDA2003 or TDA1517.
- 5v current requirements is only 24mA (!) So a small 5v regulator
was used with no additional heatsinking required.
- Plug in replacement for the original sound board.
- No support for the speech board.. well not yet at least..
But seeing as Defender, Joust, Robotron, Stargate, Bubbles and Splat
don't need speech that's not really a limitation for those games.
- Sounds perfect :)
More updates when I get the chance.. which may be sometime in the future
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