Native Saturn MPEG Decompression?

[Eviltaco64]

I've had some various Saturn programming docs on my computer for awhile now, and I had noticed one thing of particular interest while skimming through them:


Figure 1-1 shows the three buses and major components of the Saturn system, including the following:

SH2 CPUs. The main processor is a 28-MHz Hitachi 32-bit RISC chip (SH-2) that uses a second SH-2 as a "slave CPU" to speed processing of calculations such as matrix transformations. Both SH-2s have access to 1.5 MB of synchronous DRAM (labeled Work RAM in Figure 1-1).

System Control Unit (SCU). Includes a programmable DSP, a DMA, and a bus controller that transparently translates addresses specified by the SH-2s into appropriate control signals for the other buses.

CD-ROM subsystem. Includes a 20-MHz Hitachi SH-1 processor and an optional MPEG decompression chip, which if present connects directly to the video and sound subsystems.

These programming docs are from July of 1995, shortly after the release of the Saturn in North America. They could easily be referring to VCD cards in this instance, but somehow Hitachi managed to pull off native MPEG decompression on the Hi-Saturn and that came out in Japan in January of 1995.

This makes me wonder if it might be possible to solder a compatible MPEG Decompression chip (probably from a VCD card) onto a standard Saturn (or at least the Model 1 since that's what these docs pertain to).

This is just something I had been wondering about for awhile. I truly have no ground to stand on in all of this, so feel free to prove me wrong! ;-)

- Eviltaco64

[Druid II]

Didn't the Hi-Saturn just have a standard MPEG card preinstalled?

As long as you know the pinouts, it's probably possible to solder the mpeg card, but it would be far easier to just connect the damn thing normally, no?

[Yakumo]

The Hi Saturn did not do native MPEG at all I'm afraid. Every Hi Saturn came with a Hitachi made MPEG cartridge pre-installed. You can actually take it out and us it in a Sega or V-Saturn.

Yakumo

[Eviltaco64]

Wow, I didn't know that until now. I had thought the Hi-Saturn had native playback for the past 5 years or so because a handful of sources are apparently inaccurate. -_-

Thanks for the clarification, though! Although my dream of a fully hacked Saturn with region switches, a modchip, and built-in VCD playback have been crushed. I think I'll live though, hahaha. :thumbsup:

[Shakey_Jake33]

You still essentially have that though. The Mpeg card sits discretely in the expansion bay at the back of the Saturn. I actually completley forgot I even owned an Mpeg card until I had to change the battery.

[Druid II]

I think the Navi did have built-in mpeg functions though, didn't it? That thing was packed with so many things compared to the stock console.


Wow, I didn't know that until now. I had thought the Hi-Saturn had native playback for the past 5 years or so because a handful of sources are apparently inaccurate. -_-

Thanks for the clarification, though! Although my dream of a fully hacked Saturn with region switches, a modchip, and built-in VCD playback have been crushed. I think I'll live though, hahaha. :thumbsup:

You forgot optical S/PDIF output. It's actually doable, and worth way more than the VCD card.

[Eviltaco64]

The Hi-Saturn Navi is definitely a strange case. If it did have internal VCD playback, then I'd imagine the video quality being somewhat decent on that small LCD display it had.


You forgot optical S/PDIF output. It's actually doable, and worth way more than the VCD card.

Nice! I didn't know the Saturn was capable of outputting digital audio. That mod would be kind of pointless for me with my mid-70s Pioneer receiver, but it's definitely still interesting to know nonetheless. :P

[l_oliveira]

Some games, like Wangan Dead Heat, for example actually use MPEG streams for the movies when the card is detected

[Yakumo]

The Navi-Hi Saturn may also use the standard Hitachi MPEG cart but since I've never seen one of these Saturns in real life, I can't say for sure.

Yakumo

[Chilly Willy]

I've got one of those Hitachi HiSaturn MPEG cards... bought it from consolegoods when I got a bunch of stuff for my Saturn.