While thinking about the toolchain I realized I hadn’t ever finished implementing branch instructions. Today I added a microcode bit to negate branching (for the ‘if not’ jump instructions), and implemented the jmpnz and jmpno instructions. Also updated the test […]
As I started looking at adding ECLair’s instructions to the LLVM port, I realized that a lot of them aren’t organized in a reasonable way. For example, add16 with the source/dest register A has an entirely different pattern of bits […]
I’ve spent a bunch of my spare time over the past few months figuring out a toolchain for ECLair. I’m using LLVM so far, and have been working on learning how to port it to a new target platform and […]
Was pretty much out of microcode space, so extended the address width from 8 bits to 9. I’d known for awhile that this would likely be needed, as I exceeded 80% of the microcode space used up before even hitting […]
Finished all the 8-bit load and store operations, everything has proper unit tests and is working. While doing this it was starting to get hard to manage the single microcode definition file as it’s almost 650 lines long, and it’s […]
Decided to start tackling load/store today, which should be a lot of microcode and not much hardware work. Implemented the DP/data pointer register (had always been planned, but hadn’t needed it yet so it wasn’t there), which all load/store operations […]
Sat down and wrote out a bunch of microcode tonight, and added a couple more required transformation data paths from MAR to XY (byte swap and sign extend). Binary inversion (NOT) is implemented now in both 8/16 bit forms, as […]
Spent a bit of time implementing the “clear all internal registers” function and added it into some unit tests, which should result in more accurate testing/catching some edge cases we wouldn’t have caught before. Also simplified the return path for […]
Implemented all the shift right instructions this evening, using a latch between MAR and the XY bus that just physically connects the bits shifted over by one. The code is pretty similar to the shift left code, except instead of […]
Had a lot of TODO items to finish up the writable control store after last time, so took care of all of them today. After thinking about how to implement switching the data input lines for the CS RAM from the […]