[plug] pc66 ram

[Craig Foster]

Okey dokey....

(dredging up memories of Mac support and repairs :P )

The side notch for the 5V DIMM is centred between the two sets of pins. 
3.3V EDO/FastPage has the notch towards the outside.
3.3V SDRAM has the notch towards the centre.

Imagine this looks right for 3.3V SDRAM... :)

|UUUUUUU  | |UUUUUUUUUU | | UUUUUUUUUUUUUUUUUU|
^Outside                  ^Centre

5V EDO/FP memory is used mostly in Performa 5400/6360/6400 and PowerMac
8500/9500

3.3V EDO was for pretty much only for 7220 & *OLD* Intel LX mainboards 
(you'll know the sort when an LX mainboard has slots for 72-pin SIMMs &
168-pin DIMMs)

3.3V SD are for G3(66) & G4(100 & now 133) & the plethora of PC combos

And to make matters worse there are numerous Mac clones in the mix too.

If you put RAM in and notice that the memory doesn't quite fit, check
the RAM stick to see whether the board has marked or has grated the PCB
- indicating that you're one specification off.

Oh and 3.3V sticks in a 5V motherboard will soooooo void your warranty
(if you tell them)

Regards,

Criag F.

> -----Original Message-----
> From: Craig Ringer [mailto:craig at postnewspapers.com.au] 
> Sent: Saturday, July 06, 2002 12:28 AM
> To: plug at plug.linux.org.au
> Subject: Re: [plug] pc66 ram
> 
> 
> >
> >
> >t might pay dividends if you check out the voltage 
> requirements of the 
> >RAM and compare it to the voltage options on the motherboard.
> >
> >If I remember correctly :
> >
> >66 MHz RAM likes 5 volts and 100 MHz & 133 MHz RAM likes 2.8 - 3.2 
> >volts approx. Can somebody else confirm that for me please.
> >
> There is 5V PC66 RAM in the usual DIMM format, and there is 3.3V (?) 
> PC66 RAM in the same format. I think they're actually keyed 
> differently 
> (those friendly notches in the DIMM's board), and so 5V PC66 
> won't fit a 
> 3.3V slot, and vice versa. Your board could omit the keying 
> "pin" (ridge 
> in the slot) if it wanted to support both I guess....
> 
> In general, for very old boards with DIMM slots you need to hit the 
> manual to find out what kind of RAM it wants. This is particularly 
> aggrivating when the manual refers to support for those 
> new-fangled DIMM 
> things.... or at least provides so little info that you can't 
> actually 
> find out what kind it needs, what sizes it supports, etc.
> 
> 
> 
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