SVP Programming

[evildragon]

Just had an idea to use the SVP chip. Could it at all be possible to tape off pin B32, and use the Sega CD to run the SVP chip?

Just an idea, or can it not run external commands?

[Chilly Willy]

The SVP uses part of the rom as it's instruction memory. You would be stuck with whatever routines are in the rom.

What I've been looking into was removing the rom, putting in a ZIF socket, then using flash memory in place of the rom.

[kool kitty89]

I thought the SVP had on-chip instruction RAM as well. (or is that hard coded to automatically import code from ROM?)

[Chilly Willy]

The SVP has 2KB of IRAM that can be changed by the host (the MD). The other 126KB of program space are mapped to the rom. You won't be able to do much with only 2KB.

EDIT: Actually, that's not quite right - the MD can't access the IRAM, only the SVP can. So you can't load custom code in the IRAM from the MD for even small routines. The IRAM is mostly meant for things like constants or variables that SVP will load itself using code from the rom.

[kool kitty89]

And the SVP can't run (or import) code from the 128k buffer RAM? (I think you mentioned it accesses that RAM via I/O ports, so probably no running code from it, but maybe copying code to the I-RAM)

[Chilly Willy]

And the SVP can't run (or import) code from the 128k buffer RAM? (I think you mentioned it accesses that RAM via I/O ports, so probably no running code from it, but maybe copying code to the I-RAM)

Code can't be run from the DRAM. If the SVP had a routine in rom to copy code from DRAM to IRAM, then you could run something from IRAM. I don't know what the code for the SVP in VR does.