Pacific Northwest Anyone have any spare 512MB registered ECC SDRAM to dump?

[Chuck(G)]

I'm not sure about the reliability of some of my server SDRAM. I can play eBay Bingo, but if anyone has a couple of 512MB registered ECC SDRAM DIMMs, kicking around, and can part with, I'd like to hear from you!

 

[twolazy]

If you find any let me know. I just ordered a pair of 128mb for like 10 bux each off fleabay. Could use 1-2 512mb for the Pentium Pro server.

 

[Unknown_K]

PPro uses EDO I think.

 

[twolazy]

Correct. PR440FX uses EDO SDRAM ECC Registered. Up to 1GB per module.

Edit : 1gb max

 

[Chuck(G)]

Yeah, mine is 440GX chipset. 64x72-100MHz PC100, 168p DIMM, 3.3v, Sync, ECC

If I can't find a good deal on buffered ECC SDRAM, I'll just use PC133 unbuffered stuff--there's more of it out there.

 

[twolazy]

Ram I am looking for same size is

8x72-60ns, 168p DIMM, 3.3v, EDO, ECC, w/Bf. Guess 384mb works for now but would love to max it to 1gb.

 

[GiGaBiTe]

There's no such thing as EDO SDRAM. It's either EDO or SDRAM, not both, they're two entirely different memory technologies.

There's also no such thing as ECC EDO memory. You either have 32 bit regular memory or 36 bit parity memory, there's no error correcting.

 

[lowen]

There's also no such thing as ECC EDO memory. You either have 32 bit regular memory or 36 bit parity memory, there's no error correcting.

Sun Ultra 5 and 10 workstations also use 3.3V 168-pin EDO ECC-capable DIMMS (reference: PDF pages 218-222 of The Ultra 10 Service Manual)

ECC-capable RAM has multiple check bits available; in the case of a 168-pin DIMM it's 72 bits wide, just like twolazy said in the post just above. Whether those extra bits are used for parity or for ECC is a function of the RAM interface; the Sun document even mentions that the MCU does the ECC generation and check.

Even on the PC architecture parity was a function of the motherboard logic, not the RAM. For parity, you only need ONE extra bit; the Sun Ultra 5/10 is a 64-bit machine, with a 144-bit DRAM subsystem.

Straight parity on a 64-bit data bus needs only 65 bits; with 72 bits available you get a full extra 8-bit byte of data, the best use of which is ECC.

While I wasn't aware any PC-architecture machines ever used the EDO 72-bit ECC-capable registered DIMMS those DIMMS got used not just in the Sun boxen but also in many Cisco routers, such as the 12000-series' GRP route processor card as well as several linecards, up through IIRC Engine 3.

And, if you go to buy RAM for those Sun Ultra 5 and 10 workstations you will be ordering "3.3V EDO ECC registered (or buffered) aMx72 168-pin DIMMs" (in matched pairs, and where "a" is the number of megawords; 8Mx72 is 64MB of course).

Here's a link for an eBay auction for a Compaq-branded EDO DIMM: https://www.ebay.com/itm/203822373957

TL;DR: A 168-pin DIMM does not necessarily mean SDRAM; EDO DIMMS exist.

 

[lowen]

Yeah, mine is 440GX chipset. 64x72-100MHz PC100, 168p DIMM, 3.3v, Sync, ECC

If I can't find a good deal on buffered ECC SDRAM, I'll just use PC133 unbuffered stuff--there's more of it out there.

Don't you just love the early DIMM days? You can even get 5V 168-pin FPM RAM...the keying is different between 3.3 and 5, as well as between SDRAM and EDO. I don't remember if registered versus unregistered had keying differences....

While I always reserve the right to be wrong, if your board specifies registered RAM it has a high likelihood of not working with unregistered RAM.

However, saying that, in the 440BX chipset (the 440GX being a superset of the BX) Chipset manual on PDF page 45 we find that the timings are programmable; the only restriction is that you can't mix registered and unregistered in the system. It would depend on the BIOS chipset init code as to whether you could use either type. I never knew that; learned something new today!

Anyway, there apparently was some confusion here in this thread: 440GX is not a PPro chipset (the 450GX is that chipset, and it requires FPM RAM).

440FX is PPro; 440BX/GX is not.

 

[Chuck(G)]

I've tried unbuffered SDRAM in my board (albeit 256MB DIMMS). It works. But I've got registered ECC in there now, so I'd have to go all ECC or all unbuffered; apparently mixing is no-no.

 

[twolazy]

There's no such thing as EDO SDRAM. It's either EDO or SDRAM, not both, they're two entirely different memory technologies.

There's also no such thing as ECC EDO memory. You either have 32 bit regular memory or 36 bit parity memory, there's no error correcting.

You sure about that? Here's my manual from INTEL as example...