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The MOS 8500 Processor
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In 1985 MOS produced the 8500, an HMOS version of the 6510. Other than the process change, it is virtually identical to the NMOS version of the 6510. The 8500 was originally designed for use in the modernised C64, the C64C. However in 1985, limited quantities of 8500s were found on older NMOS based C64s. It finally made its official debut in 1987, appearing in a motherboard using the new 85xx HMOS chipset.
The MOS 8502 was also 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. 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.
The 7501/8501 variant of the 6510 was used in Commodore's C16, C116 and Plus/4 home computers, and the 2 MHz-capable 8502 variant was used in the Commodore C128. All these CPUs are opcode compatible (including undocumented opcodes). |
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