The Macintosh 6100 was one of the first PowerPC based Macintosh computers. It came in several versions 6100/60, 6100/66 and with an av card or even a DOS card mounted in it's PDS slot.
The 6100 is a jam packed machine as you can see from the photo above. Hard drive, and CD rom are SCSI with a floppy drive on the far right. In the middle are two 72 pin ram slots which can take up to 256 mb of ram. Yup, this PowerMac will run with two 128 mb 72 pin simms! The 6100 will also run with two single sided 64 mb simms using the same chipset that is used on one side of the 128 mb chip in the photo below.
The 6100 is a pretty easy machine to work on, much more so than the 7100 or the 8100. The 128 mb simms slide in perfectly with plenty of room above so you can close the case.
An interesting discovery is that my 6100/66 can accept up to 256 mb of ram vs my 7100/66 which will not see these 128 mb chips. The 7100 will also not see the full 64 mb when I installed 4 64 mb chips in it tonight! It saw both my single and double sided chips as 16 mb each while the 6100/66 and my Quadra 605 can run all of the above chips at their full rated capacity!
Not much difference visually when you install two 64 mb simms.
Fully loaded with two 128 mb simms gives you a grand total of 264 mb of ram!
The interesting twist to this story is that the PowerMac 7100 will not read four 128 mb simms! These show up as 128 mb, I have not tried four 64 mb simms yet as I only have a pair.
As far as upgrades go, Sonnet makes a G3 pds upgrade card which is quite well designed because it will fit into the av card holder and has a slot which will still accept your original av card. Another option was a pds mounted DOS card which had a single 72 pin simm slot and a 386 cpu. The card also supported a second monitor through it's built in video out port which also required a special Apple video cable. This cable could be used with a single monitor and through a keyboard command you could switch between your Windows 3.1 desktop or your Mac desktop. A kind of neat idea at the time, I own the card but quite honestly I never did find a really good use for this setup. Maybe I'll pull it back out and see if the DOS card can take more than a 32 mb simm. Granted the big downfall with the card is that using it means you revert back to the built in video memory of the 6100 which limits the size of the monitor you can drive at more than 256 colours.
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