This repository holds the files for my 8-bit “big brother” CPU to the 4-bit Crazy Small CPU. This is a von Neumann style CPU designed with 7400-style logic chips and some RAM and ROM. The CPU requires only seventeen chips, not including the clock circuitry.

The overall design of the CPU is covered in Docs/ Also read the getting started guide and the guide to building the PCB version.

As at the 18th May 2019 I have the CPU running solidly at 3.57MHz on the PCBs that I ordered from the PCB design in the Schematics folder. I’ve kept a journal with details of my progress from the initial design phase through to the successful build.

The files and folders in this repository are:

Docs, documents on the design and how to use the tools below
Examples, example programs for the CPU
Schematic, a KiCad schematic of the CPU
cas, the assembler for the CPU
clc, a very crude compiler that outputs assembly that can be given to cas
csim, a simulator of the CPU written in Perl
disasm, a tool to disassemble the instruction ROM contents
gen_alu, a program to generate the contents of the ALU ROM
gen_ucode, a program to generate the contents of the Decode ROM
journal.txt, my running journal of the design and implementation of CSCvon8
There is also a Verilog version with the top-level file being ttlcsvon8.v, the testbench is icarus_tb.v and the Makefile will build and run the Verilog testbench. Some notes on this implementation are in the Docs/ file.”


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