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:
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.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.
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! ;-)