This project is an FPGA implementation of the Hack computer architecture described in the book The Elements of Computing Systems, By Noam Nisan and Shimon Schocken.
Hardware components are described in Verilog and can be found in the Hack directory.
The assembler is written in C and is located in the Assembler directory.
Consistent version control with Vivado has wound up being a gigantic PITA to maintain transferability between different machines. The basic idea (which I've been forced to repeat manually several times) is to create a Vivado project, select the Basys 3 board, and then add all of the sources in Hack/src to the project and generate the bitstream.
See this line in the Hack.v file for the program that Vivado will try to load onto the FPGA. You will have
to ensure that this file exists and that Vivado can find it.
While the photo deserves its title of jank_ass_vga.jpg, its also the result of a lot of effort. What's happening in here is that a program (compiled by the Assembler) is running on the Hack computer architecture, which I've synthesized onto Basys3 FPGA development board. The program simply writes the value of 0b0010101010101010 (value chosen for idiosyncratic technical reasons I will not go into here) in RAM registers 16384 to 21184. Those registers are read out by a circuit (Hack/src/VGA/VGA320x240_Controller.v) that converts the individual bits stored in those registers into pixels displayed on the screen. The counting is a little bit tricky, because I needed to halve the ordinary 640x480 VGA output (which would take up 19,200 words of the 32k RAM) down to 320x240 (4,800 words).
