memory bandwidth of original Playstation/PS1 ?

[Megadrive1988]

IIRC, the main memory bus bandwidth in the original PlayStation/PS1/PSOne was around 132 MB/sec.
I assume this was just the main memory ( the 2 MB DRAM) bandwidth to the PS1 CPU (R3000A MIPs core + GTE)

what about the 1 MB of dual-ported VRAM (to the graphics chip), how much bandwidth did that have?

with PS1 to PS2, we got a huge, huge increase in bandwidth. 24x main memory bandwidth
(132 MB/sec to 3.2 GB/sec) plus the immense eDRAM bandwidth of the GS; 48 GB/sec.

 

[Megadrive1988]

not one single reply :|

certainly someone must know the answer to this simple question.....

 

[OtakingGX]

not one single reply :|

certainly someone must know the answer to this simple question.....

I do, but I'm under NDA. I can't talk about the specs of the machine...

 

[Guden Oden]

Surely any NDA about the original PS expired millions of years ago by now.

If we knew the part number of the memory ICs that would help a bit, I'd expect clock speed to be the same all throughout the system, for simplicity's sake. Well, ok, maybe not for the sound RAM then.

 

[Urian]

100-133MB/sec between the CPU and the main memory.

 

[DeanoC]

Surely any NDA about the original PS expired millions of years ago by now.

Why would the NDA run out? After all its still being used as a commercial asset to Sony (think E3 Kaz "Riidddgee Racer" )

Many NDAs are for life (like puppies really but much less likely to have good looking women go "aren't your a cute NDA, arr your so cute"...)

 

[Megadrive1988]

100-133MB/sec between the CPU and the main memory.

that I know, as I said in my OP that the bandwidth of the main memory was 132 MB/sec


what about the bandwith of the 1 MB VRAM ?

 

[Crossbar]

Many NDAs are for life (like puppies really but much less likely to have good looking women go "aren't your a cute NDA, arr your so cute"...)

I guess you are more likely to have fat nerds with greasy hairs that go: "Oh you know the juicy details that are under NDA you lucky bastard, can I have your autograph on my mouse pad".

I guess game development isn't that glamorous that some might think.

 

[Urian]

Ok, now I know that I must get or surpass the level of nAo or DeanoC for to have complete information.

Thanks to me for giving me a more reason to live.

 

[Megadrive1988]

so some of you are telling me that, with the 1 MB of VRAM in PS1, the bandwidth to the graphics chip is under NDA ?

1993 technology, released in 1994, 1995, still under NDA. oh geeez.

 

[Squeak]

Well, here is a picture of the PCB board for one of the early non cost reduced Playstations: http://upload.wikimedia.org/wikipedia/en/c/c2/Psboard_800.jpg
Maybe someone with a bit of insight into RAM chips, can tell us which one is the VRAM and what are data pins and what are control pins? Then it should just be a matter of multiplying with the clock speed of the bus.

 

[OtakingGX]

so some of you are telling me that, with the 1 MB of VRAM in PS1, the bandwidth to the graphics chip is under NDA ?

1993 technology, released in 1994, 1995, still under NDA. oh geeez.

I was just joking, which I did not make apparent. Had I told you the same thing face to face, though, you'd probably still have believed me. I've got a pretty good poker face.

 

[Megadrive1988]

I was just joking, which I did not make apparent. Had I told you the same thing face to face, though, you'd probably still have believed me. I've got a pretty good poker face.

ahh i see. yes, it's often difficult to "get" joking and sarcasm in text. and even more so with me, i usually don't understand jokes unless someone holds my hand through it, lol.


guys, i still wanna know the bandwidth of PS1 VRAM><graphics chip, or somehow, does everything go through the ~132 MB/sec main memory?

Well, here is a picture of the PCB board for one of the early non cost reduced Playstations: http://upload.wikimedia.org/wikipedia/en/c/c2/Psboard_800.jpg
Maybe someone with a bit of insight into RAM chips, can tell us which one is the VRAM and what are data pins and what are control pins? Then it should just be a matter of multiplying with the clock speed of the bus.

thanks for that Squeak, now someone with actual knowledge & brains (not me lol) figure this out

 

[Urian]

so some of you are telling me that, with the 1 MB of VRAM in PS1, the bandwidth to the graphics chip is under NDA ?

1993 technology, released in 1994, 1995, still under NDA. oh geeez.

1989 Technology, take SGI R3000A with Geometry Engine (4 units) and reduce it to 2 units and put an H.261 decoder and you have PSone CPU.

 

[Megadrive1988]

1989 Technology, take SGI R3000A with Geometry Engine (4 units) and reduce it to 2 units and put an H.261 decoder and you have PSone CPU.

okay fair enough. what about the PS1 "GPU" ?

 

[Guden Oden]

1989 Technology, take SGI R3000A with Geometry Engine (4 units) and reduce it to 2 units and put an H.261 decoder and you have PSone CPU.

Hum, The GTE is AFAIK an original work by Sony (perhaps with outside help of other engineers), and not some sort of cost-reduced SGI transplant...

SGI has in my recollection never been mentioned in conjunction with playstation during the 12+ years since the original PS launch, other than perhaps in passing like an object of reference or such.

 

[Urian]

Hum, The GTE is AFAIK an original work by Sony (perhaps with outside help of other engineers), and not some sort of cost-reduced SGI transplant...

SGI has in my recollection never been mentioned in conjunction with playstation during the 12+ years since the original PS launch, other than perhaps in passing like an object of reference or such.

I don´t know if is an original work or not, but I believe that isn´t an original work only because you can reduce the size of a R3000+Geometry Engine to a less size and put 2 instead of 4 geometry engines inside the chip. Is true that GTE is a pure Sony design but the "only" that Sony did was to put 2 Geometry Engines inside the CPU and they added an H.261 decoder.

 

[Squeak]

AFAIR much of the technology in the org. PS was cost-reduced and tweaked from a 1984 realtime 3d project and high-end product, called System G. Also with KK at the helm.

 

[MrWibble]

AFAIR much of the technology in the org. PS was cost-reduced and tweaked from a 1984 realtime 3d project and high-end product, called System G. Also with KK at the helm.

My memory is slightly different. From what I remember, System-G was a realtime 3D system developed for broadcast TV applications. KK didn't run the project, but at the time was a researcher in the same division of Sony, and saw the system in action. Supposedly at the time KK wanted to put technology like that into consoles (which were very basic back then) but of course had to wait for his opportunity. The people responsible for System-G eventually turned into the R&D group at SCEI responsible for PS1, by which point KK was in charge.

In some sense PS1 was built from off the shelf components, even though it seems like a pretty customised design.

 

[Megadrive1988]

I don´t know if is an original work or not, but I believe that isn´t an original work only because you can reduce the size of a R3000+Geometry Engine to a less size and put 2 instead of 4 geometry engines inside the chip. Is true that GTE is a pure Sony design but the "only" that Sony did was to put 2 Geometry Engines inside the CPU and they added an H.261 decoder.

actually I think the GTE is pretty much an original work by Sony. it's not the same as a Geometry Engine in an SGI.

SGI's old old old Geometry Engines, were (i think) made from Intel chips, and based on floating point.

whereas the GTE in PS1 used fixed point

i'm not a tech-expert though. I do know (or rather, think that I remember) that SGI later replaced the Intel chips with their own custom Geometry Engines.

I am really not sure that the Geometry Transform Engine inside PS1 CPU has anything in commen with SGI's Intel-based or custom Geometry Engines, but maybe they do.