Mostek 3870 controllers
The 8-bit single-chip microcomputer MK3870 was introduced already in the year 1977.
In the beginning of microprocessor production Mostek was a second source of Fairchilds F8. Both designed one-chip microcomputers around the F8. Fairchild designed the F3859, which was a simple combination of the F3850 CPU and F3851 PSU on a single chip. Mostek developed a more ambitious one-chip microcomputer, the MK3870. Mostek developed this MK3870 ahead of the Fairchild F3859. Therefore, Fairchild dropped the F3859 and became a second source for the 3870.
The MK3870 is a complete 8-bit microcomputer on a single MOS integrated circuit. It is manufactured in a N-Channel ion injection silicon-gate technology compared to the ion-implantation, depletion-mode load, P-channel MOS process of the MK5020. The MK3870 can execute the F8 instruction set of more than 70 commands, allowing expansion into multi-chip configurations with software compatibility. The device features 2048 bytes of ROM, 64 bytes of scratchpad RAM, a programmable binary timer and interrupt, 32 bits of TTL compatible I/O and a single +5V power supply requirement.