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Classic Mac Hardware (Troubleshooting, Upgrading, & Modifying) => General Hardware Discussions => Topic started by: themantimeforgot on April 29, 2019, 04:23:19 AM

Title: 8600 Upgrades
Post by: themantimeforgot on April 29, 2019, 04:23:19 AM
Hello All,

Recently I have been gifted with a Apple Macintosh 8600 and I'm looking to upgrade the system a little bit (For gaming) as it definitely has room for expansion. However having been mostly a PC guy all my life I'm having trouble with the hardware components. Specifically the HDD and Ram parts. The Key slots on the RAM seemed to be a little different than the typical 186pin PC100 RAM. Is there a reason for this? Is it keyed specifically for buffered ECC RAM or is this something unique to apple computers? As for the HDD can anyone recommend a good PCI IDE controller that is apple compatible? SCSI drives and converters seem to be in short supply these days so I would like to able to swap to IDE if I could or SATA if its even possible. Thanks for any help provided.
Title: Re: 8600 Upgrades
Post by: ovalking on April 29, 2019, 07:44:39 AM
The 8600 uses 168pin DIMMs (70nS). These were used on the majority of pre-G3 PCI Macs.

Learn more about your machine here

When you've got enough RAM, suggest you get a G3 card.

I've no experience with IDE or SATA cards.
Title: Re: 8600 Upgrades
Post by: themantimeforgot on April 29, 2019, 10:28:43 AM
Thanks for the response ovalking. I found everymac page as well but after purchasing some RAM 128mb DIMM RAM I couldn't put the RAM into the system because the slots on the bottom are slightly off. Below are some images I pulled off duck duck go to illustrate the differences I see. Do you happen to know why these slots don't match up or why the slots are different to begin with? Sorry, trying to educate myself on these things.

Apple RAM: Notice how the slot by the small end is centered and the slot in the middle is off to the side.

Typical PC RAM: where the slot on the small end is off to the side on the slot in the middle is centered.
Title: Re: 8600 Upgrades
Post by: themantimeforgot on April 29, 2019, 10:47:03 AM
So I think I found the answer to my question about the RAM.

A PM7300 uses unbuffered, 70ns, 5volt, FPM DRAM, versus SDRAM (usually 10ns, 3.3volt). The notch difference you see is (I believe) related to voltage, although even if the voltages matched, it still wouldn't work.

Each notch can be in 1 of 3 positions: Left, center or right.

Holding the DIMM such that the notches are on the left most, they can be defined:

First notch set:
C: Buffered
R: Unbuffered

Second notch set:
L: 5.0 Volt
C: 3.3 Volt
R: Reserved
Title: Re: 8600 Upgrades
Post by: refinery on May 01, 2019, 12:46:12 PM
yes the PC-66 RAM as you have pictured is 3.3v 168-pin RAM. the older power mac memory is 168-pin 5V memory, and as such, the two are not compatible with each other.

doing an ebay search or whatever for "168 pin 5V RAM" should give you sufficient options. i would try to look for ones that say they are mac compatible. back in those days it was kind of a guessing game of slight variations in standard (such as some macs needing FPM RAM while others could use EDO)