Microprocessors

ARM9 is a group of older 32-bit RISC ARM processor cores licensed by ARM Holdings for microcontroller use.
The ARM9 core family consists of ARM9TDMI, ARM940T, ARM9E-S, ARM966E-S, ARM920T, ARM922T, ARM946E-S, ARM9EJ-S, ARM926EJ-S, ARM968E-S, ARM996HS.
Since ARM9 cores were released from 1998 to 2006, they are no longer recommended for new IC designs, instead ARM Cortex-A, ARM Cortex-M, ARM Cortex-R cores are preferred.

S2000 is a family of 4-bit microcontrollers manufactured by American Microsystems, Inc (AMI) in the first half 1980.
Depending on part number, 2000 or 215x, the microcontroller had either 32 or 40 byte on-chip scratchpad RAM, and 1 KB or 1.5 KB ROM.

In April 1975 Fairchild began sampling the F8 processor with production quantities available in the fall of 1975.

Hitachi Semiconductor PMOS 4-Bit Single Chip Microcomputer

Hitachi IC HD-38820-L28, VTR Custom 4-Bit Microprocessor HD 38820-L28

The 6502 is an 8-bit processor designed by MOS Technology in 1975, based on the design of the Motorola 6800.

The COP444L is one model of a family of microcontrollers from National Semiconductor.
It has 2K of 8-bit ROM and 128 4-bit nibbles of RAM.
One handheld game that used it is Entex Space Invader. It can be electronically dumped.