203 FROG 4-Bit CPU

203 : FROG 4-Bit CPU

  • Author: ChrisPVille
  • Description: The FROG is an extremely minimal load-store 4-bit CPU
  • GitHub repository
  • Most recent GDS build
  • HDL project
  • Extra docs
  • Clock: 0 Hz
  • External hardware: An SRAM/ROM like memory containing instructions should be connected to addr/wcyc/data_in

How it works

The CPU addresses external memory on its addr pins and executes/interprets data on the data_in pins

How to test

Set data_in to 0x8 (NOP) and observe the addr bus count upward as the CPU executes Instructions


# Input Output
0 clock addr[0]
1 reset_p addr[1]
2 data_in[0] addr[2]
3 data_in[1] addr[3]
4 data_in[2] addr[4]
5 data_in[3] addr[5]
6 none addr[6]
7 fast - zero wait state memory mode write memory cycle