Mostek 3870 (MK3870) microcontroller family

The 3870 (MK3870) 8-bit microcontroller is a single chip implementation of Fairchild F8 (Mostek 3850). The microcontroller includes up to 4 KB mask-programmable ROM, 64 bytes scratchpad RAM and up to 64 bytes executable RAM. The MCU also integrates 32-bit I/O and programmable timer. In addition to generic MK3870/xxx-xx markings the 3870 chips also have device order number in the form "MK#####x-xx".

Mostek also produced MK38P70 - development version of the 3870 MCU that supported external EPROM chip.