MOS Technology 8502

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The MOS Technology 8502 was an 8-bit microprocessor designed by MOS Technology and used in the Commodore 128. Based on the MOS 6510 that was used in the Commodore 64, the 8502 added the ability to run at a double (2.048 MHz) clock rate, in addition to the standard 1.024 MHz rate used by the Commodore 64.

Since the 40-column VIC-II display chip could not "steal" sufficient cycles when the CPU ran at double speed, video display in fast mode was available only with the 80-column VDC. Some 40-column applications selectively disabled the screen when performing CPU-intensive calculations so that the additional speed could be utilized when the loss of video output was unimportant.

The pinout is a little bit different from the 6510. The 8502 has an extra I/O-pin and lacks the PHI2-pin that the 6510 had.

65xx-series CPUs from MOS Technology, second source/clone vendors, and the Western Design Center

MOS 4510 ● MOS 6501 ● MOS 6502 ● WDC 65C02 ● Hudson HuC6280 ● Ricoh 2A03 ● MOS 6507 ● MOS 6508 ● MOS 6509 MOS 6510 (and 7501, 8500, 8501) ● MOS 8502 ● MOS 65CE02 ● WDC 65802 ● WDC 65816 ● Ricoh 5A22 ● Nintendo SA-1