Sega Pluto

Pluto (Roger's)

I've uploaded some images from the "Fixing the Super Rare Sega Pluto Prototype" video to Google Drive .

Quick Theory and Speculation


The Pluto is largely the same as the stock Saturn with some small changes. Besides ASIC revisions, alternate parts, and layout changes what makes the Pluto unique is the extension of the cartridge slot to an external bus for the modem and hard drive. The cartridge-to-external-bus is buffered with some bus transceivers which appear to be controlled by IC50.


IC50 looks like it might also act as a middleman between the cartridge and external bus. IC50 is probably some Altera or Xilinx FPGA, or maybe Lattice based on the part choice for IC52.


Considering that the Modem and HDD PCBs don't appear to be from SOJ or Cross Products, the use of a Seagate HDD instead of a Hitachi one, and that both Pluto's were discovered in the US, my guess is that the Pluto was made by SOA to sell the idea of including a modem and hard drive in the Saturn to SOJ. Or maybe as a concept idea for the Dreamcast? I don't remember all the rumors and stuff from this time period. But going through all the trouble and engineering effort to make it look like a commercial product is a bit much for a simple proof of concept.

Disorganized Info

Item Sega No. Manufacturer Manufacturer No. Variant No. Details
PSU XR959 Yamaha 35M11U   100-120V 50/60Hz
PC/IC BD PLUTO MAIN 837-12472   171-7211B   C SEGA 1996
IC501   Hitachi   2.02  
IC1, IC2   Hitachi HD6417095   SH-2
IC17 315-5687        
IC 315-5690        
IC 315-5688        
IC SF4 YGR019B        
IC6 315-5914        
IC7 MPR-17941-T        
IC50         80pin QFP
IC9 315-5744 Hitachi HD404920FS    
Modem PCB G963AAA_R_MODEM_A        
HDD PCB PCB_G963AAA_HDD_A   3314-2091    
IC52   Lattice     SETUPTIME
MOTHER     3314-2096   PLOTECH

Disc Drive looks like a variant of this one

Modem and HDD PCBs not "MADE IN JAPAN". The "part number"s do not fit any Sega or Cross Products numbering scheme, they're more like file names.

Modem and HDD connect to MOTHER which connects to IC50 and the cartridge slot. Bunch of LS245 bus transceivers probably for buffering.

PLUTO 02 (Super Magnetic's)

Bottom Text