[1] The primary change from the 6502 is the addition of an 8-bit general purpose I/O port, although 6 I/O pins are available in the most common version of the 6510.

In addition, the address bus can be made tristate and the CPU can be halted cleanly.

It is possible, by writing the correct bit pattern to the processor at address $01, to completely expose almost the full 64 KB of RAM in the C64, leaving no ROM or I/O hardware exposed except for the processor I/O port itself and its data directional register at address $00.

It finally made its official debut in 1987, appearing in a motherboard using the new 85xx HMOS chipset.

[4] It is used in Commodore's C16, C116 and Plus/4 home computers, where its I/O port controls not only the Datasette but also the CBM Bus interface.