forums.ps2dev.org

Can anyone explain to me how I can do programming for a psOne? Is it exactly like the IOP? Thanxalot if you can explain this to me or point me to a good tut. Thanx,
SKiTZo

Not sure if these links still work, but there seems to be a lot of info here:

http://home.hiwaay.net/~jfrohwei/psx/other.html

raizor

Try searching for the psx.pdf file in Google --- it's a good overview of the PS1 architecture.

Teaeg

I imagine you are talking about this:
http://www.zophar.net/tech/files/psx.pdf

Zophar's site has a lot of good emulation information on it. If you can't find an emulator for something on Zophar's Domain, it doesn't exist. :)

The tech sections are pretty good too. Just about every non-proprietary doc out.

Yes, I was referring to this document. Another good reference is Toshiba TX39 related datasheets --- PS1 CPU and IOP are derivatives/modifications of TX39.

Fot me the differences between the PS1 CPU and the IOP are more interesting. For example,
the IOP does not have PS1 GPU unit. So, in the PS1 emulation mode there must be a hardware
mechanism to intercept the access to the GPU memory--mapped registers and to re-route them
to the emulation code running on the EE--GS pair. Similarly, I do not think that IOP has build--in
MDEC harwdare of PS1 --- in the emulation mode it also must be emulated by the EE.

I am not sure if anyone has looked carefully how this is done --- what IOP registers are allocated for enabling/disabling these features?

Teaeg

Actually, that is not correct. The PS1/IOP cpu are NOT derivatives of any Toshiba chip. LSI Logic did the CPU for the IOP and PS1.

However, any MIPS R3000(A) class CPU w/o FPU would be close enough, but won't include extensions such as the PS1's GTE coprocesser. So for the most part, the Tx39 datasheets would work.

Perhaps you were thinking of the EE, which was done by Toshiba, and for which the TX79 was a derivative, or vice versa.

teaeg wrote: Fot me the differences between the PS1 CPU and the IOP are more interesting. For example,
the IOP does not have PS1 GPU unit. So, in the PS1 emulation mode there must be a hardware
mechanism to intercept the access to the GPU memory--mapped registers and to re-route them
to the emulation code running on the EE--GS pair. Similarly, I do not think that IOP has build--in
MDEC harwdare of PS1 --- in the emulation mode it also must be emulated by the EE.
Teaeg

The IOP does have the MDEC. The IOP has pretty much everything the PS1 CPU had and alot more, but not including the GPU.

The PS1 GPU was a DMA device to receive lists of graphics primitives. In the PS2, these DMA channels are replace by the SIF DMA channels (with no perceived difference by the IOP) and the graphics processing is emulated by a software program running on the EE which converts the lists to a format understood by the GS.

Thanks for the explanations.

Teaeg