 thumb|300px|mos technology sids. the right chip is a 6581 from mos technology, known at the time as the commodore semiconductor group (csg.) the left chip is an 8580, also from mos technology. the numbers 0488 and 3290 are in wwyy form, i.e. the chips were produced week 4 1988 and week 32 1990. the last number is assumed to be a batch number. the mos technology 6581/8580 sid (sound interface device) is the built-in programmable sound generator chip of commodore's cbm-ii, commodore 64, commodore 128 and commodore max machine home computers. it was one of the first sound chips of its kind to be included in a home computer prior to the digital sound revolution. together with the vic-ii graphics chip, the sid was instrumental in making the c64 the best-selling computer in history, and is partly credited for initiating the demoscene. the sid has , which was filed on february 27, 1983, and issued on july 7, 1987. the patent expired on july 7, 2004. == design process == the sid was devised by engineer robert "bob" yannes, who later co-founded the ensoniq digital synthesizer company. yannes headed a team that included himself, two technicians and a cad operator, who designed and completed the chip in five months, in the latter half of 1981. yannes was inspired by previous work in the synthesizer industry and was not impressed by the current state of computer sound chips. instead, he wanted a high-quality instrument chip, which is the reason why the sid has features like the envelope generator, previously not found in home computer sound chips. {{quotation|i thought the sound chips on th
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