Discrete CPU

A Discrete CPU is required to build a Perspicuous Computer 1.

A Discrete CPU would typically have a small word-width, either 4-bit, 8-bit or possibly 16-bit due to cost, complexity etc. As per the Perspicuous Computer 1, it would be built from NPN Bipolar Junction Transistors (BJTs) and be compatible with existing TTL logic.

Monolithic

One option is to build a monolithic CPU modelled after some existing CPU, such as the MOS Technology 6502 (approx. 4k transistors) or the Intel 4004 (approx. 2.8k).

Modular

Another approach is the emulate existing TTL 7400 series chips that have been used to make CPUs in the past, each as a separate module. These modules can be fabricated in higher quantities and then wired together as if they were 7400 series logic devices.

• Discrete 74181 - 4-bit ALU

External Links

• Homemade CPU - From Scratch by Mikhail Svarichevshy (from Russia)