MOS Technology 8502
From Free net encyclopedia
Image:MOS 8502R0 3686 top.jpg The MOS Technology 8502 was an 8-bit microprocessor designed by MOS Technology. 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.