Weekly PSX core progress (Patreon)

Hi everyone!

If you are interested in the full list of changes, you can see them on the Github page: https://github.com/RobertPeip/PlayStation_MiSTer/commits/main

You might have to click the three "..." near a commit to reveal the hidden commit text.

As in total these are 23 changes, I will not list them all here, but instead wrap them up by the main points.

- DMA now has it's basic implementation done. So far it only implements 2 of the the 7 DMA channels, but the critical point, the memory access to SDRAM for read and write and the busswitch with the CPU is done. The other channels are mainly missing, because the targets (e.g. MDEC, SPU) are not there yet. Also DMA pausing needs to be added later on.

- All 3 Timer modules are implemented and working, but most likely still contain bugs. The Timer0 external mode, which uses the video clock instead of the CPU clock, is not yet done, as I need to figure out how to properly handle it for PAL/NTSC and different Pixelclock rate modes. 

- A lot of bugfixes for CPU and GPU are also added. As it's still early in the project, bugs still pop up very often at all situations, but fortunatly are easy to track with the simple testroms I'm running currently.

- Simulation environment is further improved, allowing to test all GPU render situations from a savestate of my(or most other) emulator without simulating the whole system, which speeds up rendering. It renderes one image in less than 10 seconds(for a 60 fps game), which is insanely fast, considering it captures all internal signals of the GPU for every clock cycle, to debug them later on.

So what's next?

- CPU has a data cache, which acts as scratchpad memory, that is still missing

- Co-Processor 2 instructions(GTE-communication) in the CPU needs to be added

- Some general system registers(e.g. Memory Control) need to be implemented

That's not really exciting, but homework that must be done before the project can go further.

After that I will start with the GTE.

That's it for now.

Have fun!