235 Basic 4 bit cpu

235 : Basic 4 bit cpu

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  • Author: Noah Gaertner
  • Description: 4-bit CPU that does add, subtract, multiply, left and right shifts, conditional jump based on external signal, logical and bitwise AND and OR, equality and inequality checking, bitwise inversion, and logical NOT
  • GitHub repository
  • Clock: 0 Hz

How it works

Implements a highly reduced ISA that fits on the limited allowed space, and uses a 4-bit bus to get the program and data values in and out of the chip, in addition to a two bit bus to tell it what to do at any given time, as well as a clock and reset signal

How to test

Write a program for the ISA and try to run it! Remember you need to synchronously RESET and then SETRUNPT to the proper value before you try to do anything!

External hardware

test pattern generator, output reader (will probably work with just an arduino for both)

Picture

IO

#InputOutput
0clockprogram counter
1resetprogram counter
2instructionprogram counter
3instructionprogram counter
4dataoutput data
5dataoutput data
6dataoutput data
7dataoutput data