Editing Commodore 64 (section)

==== ICs ====
[[File:C64motherboard.jpg|thumb|right|upright=1.6|alt=See caption|An early C64 motherboard (Rev A [[PAL]] 1982)]]
[[File:C64Cmotherboard.jpg|thumb|right|upright=1.6|alt=See caption|A C64C motherboard ("C64E" Rev B PAL 1992)]]
The VIC-II was manufactured with 5-[[micrometre|micrometer]] NMOS technology{{r|ieee85}}, and was clocked at {{nowrap|17.73447 MHz}} (PAL) or {{nowrap|14.31818 MHz}} (NTSC). Internally, the clock was divided to generate the dot clock (about 8&nbsp;MHz) and the [[two-phase clock|two-phase system clocks]] (about 1&nbsp;MHz; the pixel and system clock speeds differ slightly on NTSC and PAL machines). At such high clock rates the chip generated considerable heat, forcing MOS Technology to use a ceramic [[dual in-line package]] known as a CERDIP. The ceramic package was more expensive, but dissipated heat more effectively than plastic.

After a redesign in 1983, the VIC-II was encased in a plastic dual in-line package; this reduced costs substantially, but did not eliminate the heat problem.{{r|ieee85}} Without a ceramic package, the VIC-II required a [[heat sink]]. To avoid extra cost, the metal [[radio frequency|RF]] [[electromagnetic shielding|shielding]] doubled as the VIC's heat sink; not all units shipped with this type of shielding, however. Most C64s in [[Europe]] shipped with a cardboard [[Electromagnetic shielding|RF shield]] coated with a layer of metal foil. The effectiveness of the cardboard was questionable; it acted instead as an insulator, blocking airflow and trapping heat generated by the SID, VIC, and PLA chips. The SID was originally manufactured using NMOS at 7 micrometers and, in some areas, 6 micrometers.{{r|ieee85}} The prototype SID and some early production models had a ceramic dual in-line package, but (unlike the VIC-II) are very rare; the SID was encased in plastic when production began in early 1982.