Boris - One of the first consumer chess computer

The Boris 3850 processor


Fairchild F8


Fairchild F8 or 3850 is a multi-chip microcontroller. The F8 is based on the 3850 chip - this chip integrates 8-bit ALU, 64-bytes scratchpad RAM and two 8-bit I/O ports. The 3850 does not decode instructions - 3851 or 3856 program storage unit (PSU) chips, dynamic memory interface (DMI) chip, 3853 static memory interface (SMI) chip or 3861/3871 parallel I/O (PIO) chips are used for this task. If necessary, multiple PSU, DMI, SMI and PIO chips can be used together with one 3850 ALU chip.


The PSU chips include the following on-chip features:

  • ROM: 1 KB for the 3851 and 2 KB for the 3856;
  • Memory addressing logic;
  • Two 8-bit I/O ports;
  • Interrupt logic;
  • Timer;
  • SMI, DMI and PIO chips don't have on-chip ROM.


One-chip implementation of F8, Mostek 3870, was released in 1977.


Where is it now?
The F8 was used in the company's Channel F Fairchild Video Entertainment System in 1976. By the end of the decade, Fairchild played mostly in niche markets, including the "hardened" IC market for military and space applications, and in Cray supercomputers. Fairchild was acquired by National Semiconductor in the 1980s, and spun off again as an independent company in 1997.


Référence / reference :