My First Quadra

[Gorgonops]

The original RAM SIMM that must have been in it when it was bought has 60ns chips as well. The three remaining SIMMs that must have been added later on are 70ns and 80ns.

My guess would be that the RAM controller reads the presence detect lines of any installed SIMMs and sets memory access parameters to match the slowest memory installed.

Thank you Bolle for the information! This is very useful. Perhaps a Centris 650 would be a better thing to look at, as that was before the speed bump to 33MHz for the 650 series.

I think you want to see *both* a Centris 650 and a Quadra 650 board, because there's two questions outstanding:

#1: Was the Centris 650's board RAM really different from the 800's? (It seems reasonable that it could be because there are *other* differences, IE, different speed clock crystal and, on some boards, missing Ethernet hardware)

#2: Did the differences go away when the Centris 650 morphed into a Quadra at the same speed as the 800, meaning the sources that claim there's still a difference in RAM speed are wrong? (My feeling would be that it would have been pointless for Apple to keep populating different RAM on the boards for two otherwise identical models and the sources are just mistakenly carrying over info about the Centris, but Apple *is* known for doing silly things.)

 

[Macdrone]

isnt the bigger number faster ram?  wouldnt 80ns ram be better?  Newer computers default to the slowest ram in the system maybe thats the case?  My 7500 with G3 actually has settings for better ram speeds.

 

[Gorgonops]

isnt the bigger number faster ram?  wouldnt 80ns ram be better?

No. The number in question is the minimum cycle time, measured in nanoseconds (billionth of a second). RAM that can reliably complete a read/write cycle in 60ns can, for instance, theoretically handle almost 17 million transactions per second, while 80ns RAM would be limited to 12.5 million in the same period.

 

[Macdrone]

so ram speed now is reverse then? The speed of new ram is larger number the better.  

 

[Macdrone]

never mind, I remember its the reciprocal deal, ns to mhz.  Had a brain fart there.  The program for my accelerator is in mhz not ns.  Didnt even realize it.

 

[Themk]

It's all okay. It's easy to confuse things sometimes. When you look at the latency of modern memory, lower is better, yet at the same time higher frequency is better too. It's just one of those things to look out for.

Does anybody have more info on Wombat (650/800) boards, and their soldered-on RAM?

 

[CC_333]

I just realized I do have a Centris 650. I can open it up and take a look?

Just tell me what to look for....

c

 

[Themk]

We are wanting to know about the soldered on RAM.

Either identify the chip type to us, or if you can take a high quality photo of the ICs, making the printing on top of them easy to read.

 

[Cory5412]

Since there were two versions/configurations of the Centris 650, when getting this information it would help to know what configuration you have. Of particular concern is the Quadra 650 with the 33MHz CPU, since it should be identical to the Quadra 800, but may not be at certain benchmarks.

 

[Themk]

So many confusing names!

Yes, make sure you have the 25MHz Centris 650 for this test.

A Quadra 650 would be good for comparison, but, I have a feeling it will be identical to the 800, as both are now at 33MHz.

 

[Cory5412]

It woudl be ideal to get information on all models - 25MHz Centris 650, 33MHz Centris 650, and 33MHz Quadra 650.

The claim earlier in the thread was that the otherwise literally physically identical Quadra 650 and Quadra 800 have slightly different RAM specs.

What would be interesting to know is if the Quadras are actually the same, or if they're actually different, and if the Centrises are more different.

 

[Themk]

Yeah.

Thanks to Bolle for inspecting an 800, we have 1/3 of the systems inspected now.

Centris 650 owners, please speak up!

Quadra 650 owners, please speak up!

 

[Cory5412]

Has somebody looked at one of the 650 boards already?

 

[Themk]

Nope, no one has yet. [] ]'>

 

[Unknown_K]

What are you guys looking for exactly? I have a 650 type board installed into a IIvx case (got it at a recycling place after it was stripped out) so I don't know if it was batched Centris or Quadra.

 

[Cory5412]

Specifically, the specifications of the memory onboard.

Someone dug up an alleged difference in the memory spec between the 800 and 650, although I don't remember (it's a few pages ago) what particular 650 it was.

If it's possible to know, the specific type of memory for these four systems is what we need:

• 25MHz Centris 650
• 33MHz Centris 650
• 33MHz Quadra 650
• 33MHz Quadra 800

 

[Themk]

IT would additionally be fun for hyperneogeo to take a peek at his prototype 40MHz 650/800 (Wombat) board for an additional comparison.

 

[Unknown_K]

Is there a definitive answer to the memory used? Apple would have purchased millions of chips and purchased whatever was cheapest at the time of the order that met the spec. I have VLB video cards with soldered on chips with different ratings (same type and maker just different speed).

 

[Trash80toHP_Mini]

 

[Themk]

Quadra 650? Centris 650? Quadra 800?

The above information is just as important as the RAM chips.

EDIT: Anyway, the chips that jt imaged above are 80ns FPM chips.