Tiny Instruction Set Computer - a Simple Minimal VHDL RISC Processor

Simple minimal VHDL RISC processor.

Heavily inspired by Tim Böscke and his MCPU project (Avaiable here on opencores), the processor is an accumulator based machine with an index register.

The processor, like Tim's, was designed to fit in small FPGA or large CPLD.

License is free - do with it what you will. It would be nice if you credited me, however - we all have to work.

I have no idea if implementing this core will or will not violate patents, copyrights or cause any other type of lawsuits. I provide this core AS IS, without any warranties.

Features

- Accumulator based machine
- 8 bit accumulator
- 8 bit index register

- Address modes
- immediate
- register
- indirect

- Harvard architecture
- 12 bit program word
- 10 bit Program counter
- 8 bit data memory
- 256 data memory addresses

- ALU with
- carry flag
- zero flag
- add, subtract, and nor

- 1 deep stack
- 7 states

Status

- Fits into CPLD using an old version of Xilinx webpack
- As of 2001, never tested in hardware