AES 3-5 Fast Video RAM /WE

What controls the /WE on the fast video RAM?

Working on an AES that had a botched bios install and after fixing everything I noticed that it has a capacitor tying /WE on the lower RAM to ground.

If I remove it the console goes nuts.

Pin 86 on the LSPC2-A2 controls the upper and lower fast VRAM /WE signals on MVS. I guess you can start there.

Just got an error in 00000004 address which I'm guessing is sprite related. Does the LSPC2-A2 have internal RAM like the Neo-B0 had or is it looking like the LSPC2 is bad?

Xian Xi said:

Just got an error in 00000004 address which I'm guessing is sprite related. Does the LSPC2-A2 have internal RAM like the Neo-B0 had or is it looking like the LSPC2 is bad?

Click to expand...

The LSPC2-A2 uses external through the fast and slow vram chips. The address you listed corresponds to slow vram. All the address/data/control lines of both vrams are directly connected to the LSPC2-A2.

shadowkn55 said:

The LSPC2-A2 uses external through the fast and slow vram chips. The address you listed corresponds to slow vram. All the address/data/control lines of both vrams are directly connected to the LSPC2-A2.

Click to expand...

Thanks dude, I'll check that out.

Nope. All video RAM tests good.

The way the errors look now are address errors. And if I leave the system on for 3 minutes or longer the video goes to crap. Unless there is something that can make the LSPC2 do this I would assume the LSPC is bad, gets a little warm as well. Usually the LSPC2 isn't warm at all, first time I've felt it warm up a little.


Edit:
If I run the Diagnostic bios it won't even boot, D2 on the 68k goes low, WRAM is fine and D2 is the same there as well as pin 17 of the bios, neo-d0(64) D2 is low as well. This thing keeps resetting itself but not like watchdog. I wonder if the Neo-D0 is causing all this.

NEO-D0 is the arbiter for 68k/z80 communication in conjunction with NEO-C1. It also does the decoding for the z80 memory map. Try probing NEO-C1. That does the interface between the 68k and LSPC2-A2.