Simulation model of the Atari STE GSTMCU + Shifter
This repository contains a Verilog model of the Atari STE GST MCU (Glue + MMU combo). The model tries to be an exact replica based on the schematics recovered by Christian Zietz. The code contains both the identical gate-level circuits with asynchronous clocking, and a synchronous model hopefully suitable for FPGA synthesis.
There's a Shifter implementation, too, with both Video and Sound shifting. The core of the video shifter is based on the reverse engineering work by Jorge Cwik.
The tb/ directory contains a testbench, which runs the circuits to generate waveforms for several frames. Also an rgb file is created using a RAM dump. It requires Verilator for running the tests and generate the .vcd file, and ffmpeg to convert the .rgb output to .png. To run the test:
cd tb
gzip -d stram.bin.gz
make
To see the genarated waveforms:
gtkwave gstmcu.vcd
To see a generated video frame:
make video
With the included RAM dump, the generated screen should look like:
