- GPU - Graphics Processing Unit
- APU - Audio Processing Unit
- PPU - Peripheral Processing Unit
- RAM - A 512KBytes SRAM.
So, the direction I'll take will be to separate these buses. The CPU will just write commands to the GPU over the Main Address/Data bus and the GPU will render to the VRAM. This means filling single pixels is going to be much slower but other operations like solid fills should be much better.
There is a potential problem here. I probably don't have enough pins on the GPU for two address and data buses. I'll need to work something out here. I have an idea involving overlapping address spaces and tri-state data buses. More to follow.
Finally the VMS stands for Video Memory Switcher and is a fancy cross-bar switch. I got the idea from another project: Lazarus-64