Just a lil an add-on to the "what saturn have i got, and can it be modified for backups?" list. i have owned or modified at least 14 different saturns, and i'm currently in posession of 8 of right now. this list is by no means the final word, but it should help out newbies as a general guide.
Date is found on the bottom of the saturn
R = Round Power/Reset Buttons
O = Oval Power/Reset Buttons
#/# = Pins on ribbon cable/legs on cd-rom board numbers
all assume a US saturn since i do not have PAL or Japanese saturns to look at.
Date: The Begining - March 1996
Specs: O 20/??
Prognosis: Unmodabable at this time
Notes: I have seen at least 2 seperate models of saturns from this era...one with a seperate controller board located near the top of the system, so it didn't have the plastic to show the LEDs through. the other is more common
Date: March 1996
Specs: O 20/?? (See Notes)
Prognosis: Unmodable at this time
Notes: I have personally had 1 March 1996 system and confirmed it to be a 20 pin unit. there are varying reports all over the net, including in the most detailed FAQ i could find, of some of the systems made at this date to be Round button 21/32 systems. I doubt the credibility of these reports due to my findings regarding the April 1996 units. Based on those findings, i label the March 1996 unmodifiable until proven otherwise, and completely dismiss the claims of a Round button March 1996 system.
Date: April 1996
Specs: O 21/64 (See notes)
Prognosis: Modable
Notes: This is probably one of the rarest US saturns. I have owned 3 of these babies and all 3 have worked with my older 21 pin modboard. this system is the only one that is 21 pin and still has the Disc Access light and the oval buttons. You can replace the 64 leg CD-Rom unit with a 32 leg unit. Because of the rumors regarding a March 1996 unit with round buttons, i will not dismiss the possibility of a round button April 1996....i figure it's very possible, but just highly unlikely. Modboard position should be facing outside of the saturn to make this work.
Date: May 1996 - July 1996
Specs: R 21/64
Prognosis: Modable
Notes: Major board revision here...Round buttons, disc access light removed, power supply changed slightly, mainboard and controller board combined into 1 pcb. 21 pin, 64 leg system. can swap out drive for a 32 leg. Mainboards on these tend to have to have the Mod board face to the outside of the case to make the mods work.
Date: August 1996 - December 1996
Specs: R 21/32
Prognosis: Easily Modable
Notes: pretty much the same as the above, but with 32 leg cd-rom drive units. As with other major model changes, there is a possibility that some August 1996 systems may still use 32 leg CD-Rom drives, and that some December 1996 systems use Sanyo drives. modboard should face towards the power supply.
Date: January 1997 and later
Specs: R 21/0 ????
Prognosis: Mod possible but hard, no documentation
Notes: only have seen one of these, and it happened to be the one with eh PC trap and the Sanyo CD-Rom drive. the Sanyo drive saturns are commonly considered unmodable due to just one person's sucess with it. since i have only seen 1 saturn with the sanyo drive, and since i have not seen any other January 1997 systems, i will go with the assumption that this is what they all are like. Sytems are probably swapable with a 64 or 32 leg cd-rom drive, but i haven't tried it yet to confirm.
Final Analysis:
The best saturn to own for mod capabilities is the August 1996 - December 1996 era....for 5 months this was the system sega produced, so it's pretty common. it contains the "easy" 32 leg cd-rom drive and all the pix showing the install of a mod board show the proper installation for this system in particular.
the coolest saturn to own is probably the April 1996...that system is compatible with the older shells of both US and Japanese systems (except the model 1 saturns), so you can easily swap out the shell and have a cool looking saturn. It also has the disc access light still, and i personally think it's cool to have...only thing i'd like more is if it came in a round button format, or if the buttons were turned horizontal