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MC14500 1 bit CPU (ICU)


The MC14500 is an Industrial Control Unit (ICU) that is also considered being a 1 bit processor. It was produced by Motorola, but the production has been stopped years ago. Today the MC14500 fits well into affordable FPGA's including all its peripherals and program memory. Different reasons exist to still today to use a MC14500 design:

  • Creating spare parts to for old MC14500 machines
  • Reuse of MC14500 software
  • Separation between FPGA development (VHDL code => electronic specialist) and application (application engineer)
  • Low cost PLC alternative
  • Fun to run historic stuff on modern FPGA's
  • Learning project using FPGA's, Altera Quartus II Software and VHDL

The assembler and disassembler have been written to run on modern PC's and different operating systems, this is why python got used as programming language. See . Be aware that python version 2 and 3 are not compatible. The programs were written for Python version 2. The output of the assembler produces currently just the MIF format to be used for memory in Altera FPGA's. The disassembler can be use to read a Motorola-S files that can be produced by reading out a EPROM device using a programmer. The disassembler converts such files to MC14500 assembly code that will be understood by the mc14500 assembler. This way memory width and fileformat can also be converted.

Assembler and disassembler

The assembler and disassembler are just two python scripts,have two man pages and some sample programs. Download the latest version mc14500-*.*.tar.gz". See to get some help how to install python on your computer.


Guide in html or pdf


MC14500 Simulator