Real max RDP resolution?

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asiga
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Real max RDP resolution?

Post by asiga » Wed Jan 28, 2015 2:05 pm

The specs on the net say the RDP max resolution is 640 x 480. I know most games were fill-limited, but, anyway, is this resolution limit really imposed on the RDP design, or could you for example render into a 1024x1024 offscreen buffer if you set it up? (of course I'm assuming offscreen rendering, because otherwise the resolution limit comes from the NTSC/PAL output).

And yes, I know it would be hardly useful to use the RDP for higher resolutions, because of it being fill-limited most of the times, but I'm asking just out of curiosity about its real limits.

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Narann
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Re: Real max RDP resolution?

Post by Narann » Mon Feb 02, 2015 3:32 pm

Haha!It's quite hard to have an absolute answer as I guess nobody has ever tested to fill RDP registers with weird values.

But I would say it's possible.

I think it's an interesting thing to test here

Once again, never tested.

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MarathonMan
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Re: Real max RDP resolution?

Post by MarathonMan » Tue Feb 03, 2015 2:30 pm

@asiga: I'm not expert on the RDP, but per @narann's response, do you have a flash cart or coding experience?

The RDP just draws buffers that end up getting scaled and effectively rendered by the VI, so it's entirely possible. I'm a large proponent of marshallh's 64drive and have code to dump RDRAM if you're interested in doing the heavy lifting.

If I had to bet my life on it, I'd go with angrylion's plugin, which says the width of the framebuffer is limited to 0xFFF. 4K res anyone? :D

Code: Select all

uint32_t fbw = vi_width & 0xfff;

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Narann
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Re: Real max RDP resolution?

Post by Narann » Tue Feb 03, 2015 3:06 pm

Hahaha!

During N64 days, I remember some hi rez pictures of some games (Banjo Kazoie) rendered on SGI computer. I guess it was other high end RDP but I have no clue of this.

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asiga
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Re: Real max RDP resolution?

Post by asiga » Mon Mar 02, 2015 4:10 pm

MarathonMan wrote:@asiga: I'm not expert on the RDP, but per @narann's response, do you have a flash cart or coding experience?

The RDP just draws buffers that end up getting scaled and effectively rendered by the VI, so it's entirely possible. I'm a large proponent of marshallh's 64drive and have code to dump RDRAM if you're interested in doing the heavy lifting.

If I had to bet my life on it, I'd go with angrylion's plugin, which says the width of the framebuffer is limited to 0xFFF. 4K res anyone? :D

Code: Select all

uint32_t fbw = vi_width & 0xfff;
Yes, I've (SGI) coding experience, but no n64 dev experience. My question is basically because I was wondering how much of graphics hardware from other SGI designs was reused in the RDP. You know, there's a preliminary SGI Indy emulator in MESS, which is able to boot the PROM with correct graphics by just a partial emulation of the Newport graphics... I was wondering if the n64 RDP could boot into the SGI workstations PROM :lol:

Maybe there's some microcode compatibility with some SGI graphics hw which would surprise everybody (but just wondering, I've no clues other than some people claiming it shares some of its design with the O2 CRM (aka "Crime", or MRE + VICE)

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Narann
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Re: Real max RDP resolution?

Post by Narann » Mon Mar 02, 2015 4:39 pm

I was wondering how much of graphics hardware from other SGI designs was reused in the RDP.
I'm almost sure of this answer: Nothing.
Project Reality (which will bring to RCP) was ordered by Nintendo (I even wonder if they have all rights on RCP IP). Only the CPU was a variant from r4200.
Under the hood there is maybe some similarities between RCP and some SGI chips (if you _physically_ look at them) but I'm almost sure the registers specs of RCP are unique (and this was why RCP is the holy grail of N64 emu).
I was wondering if the n64 RDP could boot into the SGI workstations PROM.
I would say: No.
First because RDP is not a CPU (and so, does not boot anything formally speaking. :P ). r4300i is. :)
Second, because, as I said, the RCP (RSP+RDP) registers are specific to RCP and there is no RCP in something else than N64.

While unlikely, you would been able to "run" a rom on a proc supporting r4300i instruction set but I'm almost sure you would not been able to see if you have nothing (sw or hw) interpreting RCP commands.
Maybe there's some microcode compatibility with some SGI graphics hw which would surprise everybody (but just wondering, I've no clues other than some people claiming it shares some of its design with the O2 CRM (aka "Crime", or MRE + VICE)
Maybe... I would say, as RCP was designed from scratch and was a brand new architecture (that was never used later), it's very unlikely. If a hacker want to spend time trying to do so he could but it's very unlikely.

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