page_title: MOS Technology 6581
section_title: Revisions
hierarchical_section_title: MOS Technology 6581 / Technical details / Revisions
caption_attribution_description: English: 6581 in ceramic DIP
context_page_description: The MOS Technology 6581/8580 SID 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 home computer in history, and is partly credited for initiating the demoscene.
context_section_description: No instances reading "6581 R1" ever reached the market. In fact, Yannes has stated that "[the] SID chip came out pretty well the first time, it made sound. Everything we needed for the show was working after the second pass." High-resolution photos of Charles Winterble's prototype C64 show the markings "MOS 6581 2082", the last number being a date code indicating that his prototype SID chip was produced during the 20th week of 1982, which would be within 6 days of May 17, 1982.
  These are the known revisions of the various SID chips: (date codes are in WWYY w=week y=year format)
  6581 R1    - Prototype, only appeared on the CES machines and development prototypes, has a date code of 4981 to 0882 or so. Has the full 12 bit filter cutoff range. An unknown number were produced, probably between 50 and 100 chips. All are ceramic packages.
  6581 R2    - Will say "6581" only on the package. Filter cutoff range was reduced to 11 bits and the LSB bit disconnected/forced permanently on, but is still on the die. The filter is leaky at some ranges and they tend to run hotter than other sid revisions. Made from 1982 until at least 1983. First 10 weeks or so of chips have ceramic packages (these usually appear on engineering prototypes but a few are on sold machines), the rest have plastic packages.
  6581 R3    - Will say "6581" only, "6581 R3" or "6581 CBM" on the package. Had a minor change to the protection/buffering of the input pins. No changes were made to the filter section. Made from before 1983 until 1986 or so. The 6581R3 since around the week 47 of 1985 made in the Philippines use the HMOS HC-30 degree silicon though the manufacturing process remained NMOS.
  6581 R4    - Will say "6581 R4" on the package. Silicon grade changed to HMOS-II "HC-30" grade, though the manufacturing process for the chip remained NMOS. Produced from 1985 until at least 1990.
  6581 R4 AR - Will say "6581 R4 AR" on the package. Minor adjustment to the silicon grade, no die change from R4. Produced from around 1986 (week 22) until at least the year 1992.
  6582       - Will say "6582" on the package. Typically produced around the year 1986 in Hong Kong.
  6582 A     - Will say "6582A" (or "6582 A") on the package. Typically produced around the years 1989, 1990 and 1992 in the Philippines.
  8580 R5    - Will say "8580R5" on the package. Produced from the years 1986 to 1993 in the Philippines, Hong Kong and in the US.
  Some of these chips are marked "CSG" ("Commodore Semiconductor Group") and the Commodore Logo, while others are marked with "MOS". This includes chips produced during the same week (and thus, receiving the same date code), indicating that at least two different factory lines were in operation during that week. The markings of chips varied by factory and even by line within a factory throughout most of the manufacturing run of the chip.
caption: 6581 produced in 1982
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