Emulator with option of unitialized RAM and VRAM

By albs_br

Master (157)

albs_br's picture

01-08-2020, 17:35

I noted my game is with a strange bug which shows only in the real Panasonic WSX machine.
To hide an sprite I point it to an unused sprite pattern, the last one, in my case the number 63.
It works perfectly in all emulators and some real machines, and even on the Panasonic WSX emulated on openMSX.

But, on the real Panasonic WSX a strange sprite pattern appears.
I'm guessing it's because there are garbage data on pattern table.
It's finally solvable with a routine filling all VRAM with zeros before do anything.

But, I would like to test it before and after the fix, and I have no real machine.

The question is: is there any emulator with this option? RAM and VRAM initialized with zeroes/a fixed byte/a random byte?

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By theNestruo

Master (228)

theNestruo's picture

01-08-2020, 17:59

In OpenMSX you can define the initial contents of the RAM in machine definition files.
See here.

By albs_br

Master (157)

albs_br's picture

01-08-2020, 18:22

Nice, but what about the VRAM?

By albs_br

Master (157)

albs_br's picture

01-08-2020, 18:57

Meanwhile, I managed to fill VRAM with a byte pattern in code and confirmed, this is causing the bug.

By Manuel

Ascended (17075)

Manuel's picture

01-08-2020, 19:35

albs_br wrote:

Nice, but what about the VRAM?

Same thing. You can also tell openMSX to call a TCL function on a read of uninitialised memory. (E.g. break.)