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ECC EDO SIMMs in Macs?


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#1 wood_e

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Posted 17 March 2008 - 08:43 PM

I'm thinking of giving my 605 a 128MB SIMM. I found some pretty sweet deals on ECC 60ns EDO RAM - will it work?

#2 equill

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Posted 17 March 2008 - 09:52 PM

Traditionally, older Macs used FPM non-ECC RAM, just as they used non-parity RAM (with the mysterious exception of a small number of parity-chipped IIci Macs, and the unmysterious exception of A/UX-running Quadra 950s). Some of the PPC Macs tolerated EDO, and a very few needed EDO.

There are larger concerns for use of 128MB cards in a Q 605:

http://macfaq.org/ha...ry.shtml#Q2.4.6

de

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#3 Bunsen

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Posted 18 March 2008 - 06:34 AM

In short, ECC RAM won't work. Parity RAM should work: the parity bit will be ignored. /edit/ I've just read the faq link above. Question: would the use of a SIMM stacker help in any way?

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#4 equill

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Posted 18 March 2008 - 09:03 AM

'Sfarzino, SIMM stackers are even scarcer than single-banked 128MB 72-pin FPM SIMMS. An interesting speculation, to be sure, but probably only if one could find nothing but single-banked 64MB 72-pin FPM SIMMS. I have two Q 605s running happily with 132MB. The 128MB 72-pin 60ns FPM SIMMs are identical, having been bought at the same time from the same source in Canada. de

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#5 trag

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Posted 21 March 2008 - 04:54 PM

There are 72 pin 128 MB SIMMs which are not uncommon. I picked up a bunch of them for an average of about $10 each, usually in batches of 8 when they were pulled out of servers. Unfortunately, I appear to have deleted my saved search on Ebay, which would have yielded up the part numbers. Ah, here we go, it's still in my SnipeSwipe listing. The 128 MB SIMMs are HP number D4893A and the 64MB HP SIMMs are D4290A. Ultimately, the manufacturer was Samsung, and there's a big long part number from them, but typically, they were labeled for sale or use by IBM or HP and bear either an HP part number or an IBM part number. But they're constructed with sixteen largish 16M X 4 memory chips manufactured by Samsung, and usually eight more 16M X 1 memory chips which are physically smaller (fewer pins and not as wide). The smaller chips are the parity chips. Sometimes the IBM SIMMs can be found without the parity chips. A long time ago someone posted a link in the Trading Post forum to a seller who was selling lots of ten 64MB SIMMs for something like $10 per lot. If I ever get organized, I'll do an inventory and sell off my excess, but what's a reasonable price for a 128 MB SIMM? I know I have a bunch of them in a big pink anti-static foam holder.

#6 equill

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Posted 21 March 2008 - 05:07 PM

As a possible guide rather than a recommendation, I paid USD15 each for four 72-pin 128MB SIMMs just over two years ago. The idea was engaging enough that I thought the price to be reasonable. I haven't seen a similar offer since, albeit I haven't been looking, either. When daylight comes I may venture out to the garage and burrow around in my 72-pin box to rediscover the chip arrangement and chip manufacturer. (I'm not inclined to play gastroenterologist with the Q 605 at the moment.) de

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#7 trag

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Posted 21 March 2008 - 05:10 PM

'Sfarzino, SIMM stackers are even scarcer than single-banked 128MB 72-pin FPM SIMMS.


The 128 MB SIMM does not need to be single banked. I know that's the popular wisdom, that the Q605 requires single banked, and I've quoted it myself in the past, and I thought I had confirmed it back when I ordered 64 MB SIMMs from Velocity and found that their single bankers work and 2 bankers don't. It all started from Lawson's well done page, which is linked to a few posts up. However, Chris did not have a clear understanding of memory chip addressing and row and column addressing when he wrote that page, so he was lacking a dimension to the testing which might have changed some of his conclusions.

Memory organization is a complicated thing, at least until you're familiar with it.

It turns out that all the 32 MB SIMMs that we use are double-banked (2 16MB banks built out of 4M X 4bit parts). And those work in the Q605. I suspect that the problem with a 2-bank 64MB SIMM would be that the memory chips would have to be organized as 11 X 12 (row X column) or 12 X 11 and that the Q605 memory controller just doesn't support that. However, it does nicely support 12 X 12 (16M chips), otherwise single banked 64MB SIMMs would not work, and it supports two banked SIMMs, otherwise most 32MB SIMMs would not work (note, you can build a single bank 32MB SIMM out of 12 X 11 parts).

There is no such thing as a single bank 128MB SIMM. It would require that the memory chips have 32M addresses (4 byte wide SIMM X 32M addresses = 128MB SIMM) which would require a row or column address to be 13 bits long (32M => 25 bits => 12 + 13 or 13 + 12) and there is not support for 13 address bits in the 72 pin SIMM. It only goes up to 12 in the SIMM specification and some machines (e.g. PM 7100, 8100) only support 11 address bits.

So, the Q605 supports double bank 128MB SIMMs because it supports 12 X 12 addressing (12 + 12 = 24 bits => 16M address X 4 bytes wide = 64MB per bank) and it supports two banks on the SIMM by diddling the (multiple) RAS and CAS signals.

I hope that adds clarity rather than obscuring things further.

#8 trag

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Posted 21 March 2008 - 05:26 PM

Oh, and I forgot to mention the important part. I've used those 2-bank 128MB SIMMs in the Q605 and they work fine. I posted a bunch of test results either here or over on Applefritter a year or two ago. My results tracked Lawson's pretty closely, which makes sense. I did not have an LCIII to test, however. The QxxxAV and the PM7100 and 8100 only seem to support 11 X 11 memory parts. So the largest possible bank is a 11 + 11 = 22 bits => 4M addresses X 4 bytes wide = 16MB. So a two bank SIMM with 16 MB/bank gives us a maximum supported 32 MB SIMM. The PM6100 does support 128 and 64 MB SIMMs even though it uses exactly the same memory controller chip as the PM7100 and 8100. This puzzled me until I used an ohmmeter to trace the connections. The PM7100 and 8100 run their address lines and their RAS and CAS lines through a largish PLD before it goes to the SIMM sockets. I don't know what happens there, but part of it is that support for 12 X 12 memory chips is lost. I suspect that chip steals the upper address bits and uses them to control access to the different SIMM slots. Anyway, that's why the 6100 behaves differently than the 7100 and 8100. However, the report on Kann's website of a pair of 256MB SIMMs in the 6100 is almost certainly false. There are four CAS and RAS lines available in the SIMM socket and the 6100 ties them together in pairs. So there are only two available to distinguish between the two banks in the 6100 SIMM socket, and the lines are used 1 hot, not binary encoded, so 2 lines give 2 choices. There does not appear to be any way to build a 4 bank SIMM which would be supported in the 6100 and given that 64MB is the largest possible bank capacity, a 256 MB SIMM would require four banks. Also note that some 128MB SIMMs, (the HP part I quoted above, e.g.) tie their RAS and CAS lines together in the opposite pattern to the PM6100 and so those SIMMs won't work at all in the 6100, although it might be possible to change the RAS tieing by moving resistors on the SIMM. The 610, 650 and 800 see half the capacity and so apparently do support 11 X 12 or 12 X 11 addressing, because they treat 12 X 12 memory chips as 12 X 11 parts. So, in theory, one could install 128 MB SIMMs in those machines and get 64MB of capacity recognized. I think. Surely I tried that...I need to find my old posting on this topic.

#9 Bunsen

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Posted 21 March 2008 - 07:15 PM

a seller who was selling lots of ten 64MB SIMMs for something like $10 per lot.

I checked him about an hour ago. He's out of stock :-/

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#10 equill

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Posted 22 March 2008 - 05:31 AM

As undertaken above, I've hauled out my 72-pin 128MB (32M x 36) SIMMs to examine. Their parity nature has, expectably, made no difference to their function in Q 605s.

The cards are 1-7/16in high, and labelled hp D4893A, as cited by trag. There are 8 x SEC KM44C16100BK-6 (5V, 4k?, 16M x 1?, FPM, 60ns) chips, and 4 x Hitachi HM5116100S6 (5V, 4k, 16M x 1, FPM, 60ns) on each side.

Some detail is not interpreted by Chipmunk.

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#11 trag

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Posted 03 August 2009 - 11:06 PM

The cards are 1-7/16in high, and labelled hp D4893A, as cited by trag. There are 8 x SEC KM44C16100BK-6 (5V, 4k?, 16M x 1?, FPM, 60ns) chips, and 4 x Hitachi HM5116100S6 (5V, 4k, 16M x 1, FPM, 60ns) on each side.


The KM44C16100BK-6 are 16M X 4, i.e., four bits wide with 16M addresses. Because there are 16M addresses, this requires 24 bits, which means the row/column organization must be 12 X 12. A 12 bit row address gives the 4K designation, as the 1K, 2K, 4K designator is just the number of row addresses, corresponding to 10 bits, 11 bits or 12 bits of row addresses.

Eight of these chips (one side of the D4893A SIMM) gives 64 MB of capacity. 16M X 4 X 8 (chips) = 16M X 32 bits and 1 byte = 8 bits => 4 bytes = 32 bits. So 16M X 32 bits = 16M X 4 bytes = 64MBytes.

Two sides to the SIMM gives 64MB X 2 = 128 MB.

I used two of the KM44C16100BK-6 to build each of my 16MB IIfx SIMMs.

Oh, and a thing I meant to mention a year ago... I've used two of the 128MB SIMMs in a SIMM doubler to take the Q605 up to 260 MB of RAM. I'm not quite sure how that works, as I wouldn't have expected there to me enough RAS lines in the Q605. One of these days I'll dig out the SIMM doubler again and trace it's circuitry.

#12 johnklos

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Posted 19 September 2009 - 10:34 PM

Oh, and a thing I meant to mention a year ago... I've used two of the 128MB SIMMs in a SIMM doubler to take the Q605 up to 260 MB of RAM. I'm not quite sure how that works, as I wouldn't have expected there to me enough RAS lines in the Q605. One of these days I'll dig out the SIMM doubler again and trace it's circuitry.


I'd be VERY interested to know about this... Not sure how it's possible, but I'd love to know more.

I have lots of 128 meg SIMMs in various Quadra 605s, two in an Amiga 1200, and in various Cobalt Raq 2 machines. If anyone wants a SIMM which will definitely work in a Quadra 605, just shop around for a 128 meg SIMM for a Cobalt Raq 2. Most of them are thin, too, so you won't have to trim the heat sink very much (if you have one).

Here's a (non-Cobalt) 128 meg SIMM in one of my Q605s:

http://boobookitty.z...m/Pages/11.html

#13 bahkyp

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Posted 08 January 2010 - 07:09 AM

I have 2 128T16E164-60KO simms working in sepparate Q605's. They are 128MB EDO 5v non-parity double banked simms. They appaer as 128MB. So both EDO and double banked work in a Q605.

Weirdly if you place them in a Q650 they appear as 64mb? I assume you could get the Q650 to 256 this way, though I have never owned more than 2 128mb simms.

Looking at buying some kahlon KAH32X32-60 128MB modules, anyone tried these?

#14 Mars478

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Posted 08 January 2010 - 03:03 PM

Just off topic, I have 4 SIMM Stackers by a company called Princeton something.
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#15 olePigeon

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Posted 08 January 2010 - 05:57 PM

Just off topic, I have 4 SIMM Stackers by a company called Princeton something.


Does your convert 30 pin to 72 pin, or is it the 72 pin expander? I have one that converts 30 pin SIMMs. I bought the wrong one. :(

#16 olePigeon

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Posted 08 January 2010 - 06:05 PM

I've bought two different brand 128MB 32x32 EDO 5v SIMMs, and both have worked in my Quadra 605 and LC 575.

#17 olePigeon

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Posted 08 January 2010 - 06:11 PM

Also, does anyone know if a Sun Raq2 module will work? Listed as 128MB 5v EDO 72-Pin.

Maybe we can put together a database of different brands (plus pictures) of 128MB RAM modules verified to work with Macs.

Edit: Nevermind, a 68kMLA thread came up in my Google search. Apparently the Sun Raq2 modules work fine in a Quadra 840av. I'll buy one and give it a test in my 605 and LC.

#18 ClassicHasClass

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Posted 09 January 2010 - 01:58 AM

Traditionally, older Macs used FPM non-ECC RAM, just as they used non-parity RAM (with the mysterious exception of a small number of parity-chipped IIci Macs, and the unmysterious exception of A/UX-running Quadra 950s).


And the Apple Network Servers, though strictly speaking those are not Macintoshes. In fact, if you put non-parity RAM in an ANS, it slows the machine down (it reduces the timing to 70ns, even if the RAM is capable of 60ns), a rare instance of parity RAM actually making a machine faster. My ANS 500 has 512MB of parity FPM, which is hard as hell to find anymore.




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