I designed and built a 16bit CPU using VHDL and the Quartus II tool on a Cyclone II FPGA.
And then I designed also in VHDL language a system for my cpu in the same FPGA chip the Cyclone II EP2C5T144.
It is a 16bit CPU with 16 bit ALU, 2 accumulators (up to 8). The system has 4K of rom, 4K of ram (up to 64K total memory) and 4K of Video Ram. I also implemented a monochrome video encoder and a UART for serial communication. It currently runs at 50MHz.
I finished writing the assembler for my cpu assembly language, I'm testing the system and I'm writing some useful system calls in the rom, soon I'll list the project sources.
Here is a photo of the Video output, with only 4K Video Ram I finally decided to implement a 204x160 pixels monochrome display, 34x20 characters using a 6x8 font :
I plan to add some software, like a basic interpreter and move to a bigger FPGA so I can use more memory for video ram and programs.
This would then be like an early 80's home computer developed form scratch (even the CPU) by me!
(maybe I'll skip the tape recorder interface)
I developed a basic calculator in assembly the first application for my system, so now I have tested most of the CPU instructions and assembler operation here is a screenshot:
Info: lliont at gmail.com