A member of the ASSEMbler Games forums asked whether I could try some of the Sophia hardware in an ordinary retail VA0 Saturn. Naturally I had to find out. The Sophia is still missing its SH-2 processor cards, which makes testing the complete machine rather difficult, so this seemed like an excellent opportunity to find out whether some of its other components actually worked.

I’ve got a retail VA0 Saturn on the bench, complete with its rather unusual CD drive arrangement. The power supply is mounted to the upper case, and the CD hardware uses a separate SH-1 daughterboard. That makes it a particularly interesting machine for this experiment, since the Sophia development hardware has a somewhat similar arrangement.

I started by installing the Sophia CD mechanism into the retail Saturn. Everything seemed to connect nicely, and the machine recognised that a drive was present. Unfortunately, inserting Sega Rally didn’t immediately produce the result I wanted. The disc wasn’t being read properly, and the spindle wasn’t always behaving itself.

After investigating the laser adjustment, I managed to get Sega Rally recognised and running. Excellent! I did have to turn the adjustment rather further than I’d have liked, though, and the drive was struggling with the disc. It looks as though this particular laser has seen better days.

Next came a backup copy of NiGHTS into Dreams. The Saturn recognised it as an audio disc rather than launching the game. I then connected a modchip, which was quite an adventure given the length and arrangement of the ribbon cables. With that fitted, the backup booted successfully. At least we now know the Sophia CD mechanism can read both pressed and recordable discs under the appropriate conditions.

The more interesting question was whether the Sophia SH-1 hardware could do anything differently. I installed the development board and tried the backup again without relying on the modchip, but there was no successful game boot. So much for that particular idea! Still, it’s useful to know how the hardware behaves when connected to the retail Saturn.

I went a little further and investigated another Sophia interface board, complete with CD and VCD mode selections. It needed an external 5 V supply, which I managed to obtain from the dismantled Sophia. The drive made different noises depending on the switch position and whether the board had power, but I couldn’t get the arrangement properly working with the Saturn.

So we’ve confirmed that the Sophia CD mechanism can run a commercial Saturn game, and it can boot a backup with the modchip fitted. The additional board experiments were considerably less successful, although at least we’ve learnt a little more about the hardware. The Sophia itself will have to wait until I can find those missing SH-2 processor cards.

I’ll also be taking more detailed photographs as everything goes back together. Yes, I am that slow at the moment. At least I’ve got another excuse to pull Sophia apart and have a good look at all those lovely Sega chips!

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