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Catalogue of Arcade Emulation Software - the Absolute Reference

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asteroid.c

0.26 [Brad Oliver, Al Kossow, Hedley Rainnie, Eric Smith, Allard van der Bas]


TODO:

- The ERROR message in Asteroids Deluxe self test is related to a pokey problem


SOUND HARDWARE NOTES:

- Asteroids Sound System Analog emulation by K.Wilkins (Nov 2000).

- The Asteroid SAUCER sound is based on two VCOs, a slow VCO feed the input to a higher freq VCO with the SAUCERSEL switch being used to move the frequency ranges of both VCOs. The slow VCO is implemented with a 555 timer and a 566 is used for the higher VCO. The sound can be tweaked with the gain and adder constants in the 2 lines below. The Fire sound is produced by a 555 based VCO where the frequency rapidly decays with time. An RC filter is used for the decay with the inverse of the enable signal used. Thrust noise is just a gated noise source fed into a low pass RC filter. Explosion generation circuit, pitch and vol are variable. The Thump circuit is based on a VCO with the VCO control fed from the 4 low order bits from /THUMP bit 4 controls the osc enable. A resistor ladder network is used to convert the 4 bit value to an analog value. The VCO is implemented with a 555 timer and an RC filter to perform smoothing on the output. The sound can be tweaked with the gain and adder constants in the 2 lines below. Life enable is just 3Khz tone from the clock generation cct according to schematics. All 7 sound sources are combined with a double adder circuit.

- The Asteroid delux sound hardware is mostly done in the Pokey chip except for the thrust and explosion sounds that are a direct lift of the asteroids hardware hence is a clone of the circuit above apart from gain scaling. The Thrust noise is just a gated noise source fed into a low pass RC filter. Explosion generation circuit, pitch and vol are variable. All 7 sound sources are combined with a double adder circuit.


WIP:

- 0.108u1: Brian Troha improved documentation in the Asteroids driver.

- 3rd August 2002: Ken Reneris submitted another small improvement to the Asteroids discrete sound emulation and added phosphorescent persistence emulation to the vector graphics drawing code, possibly improving the look & feel of vector games.

- 24th July 2002: Ken Reneris and Keith Wilkins both submitted improvements to the discrete sound system in Asteroids.

- 0.33b7: Inspired by Retrocade and Vector Dream, Bernd Wiebelt changed the vector games to use translucent vectors. Color intensities had to be lowered, if it feels to dark for you now, increase the gamma correction value.

- 0.33b2: Bernd Wiebelt adjusted timing in the vector games.

- 0.30: Neil Bradley fixed framerates in the Atari vector games.

- 0.29: Merged llander.c with asteroid.c driver.

- 0.27: Added generic EAROM routinges for the Atari Vector games, they are in src/machine/atari.c and src/machine/atari.h

- 0.26: Added asteroid.c and llander.c driver.