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Mounting PPC750GXs & PPC750FXs on ZIFs


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Hi all,

 I was wondering if it is a difficult/time-consuming thing to take a G3 processor from a broken iBook, fit it onto a ZIF-mount and use it in a Beige or B&W G3.

The processors are soldered in in iBooks, if I remember correctly, (and I've no idea how difficult it is to desolder these) . Some way would have to be found to set the speed in the G3 if the processor is faster than 500MHz.

Sonnet and friends have shown that it is possible, the question is whether it is worth anyone's while to offer such a service.

Is this really unfeasible?

aa

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The clock multiplier bits seem like the most simple part of such an upgrade.

 

What's the clock differential between said iBook G3s and those on existing ZIF cards?

 

Wouldn't it be easier to just upgrade an existing Zif card?

 

Seems more of a Hacks Forum feasibility study topic than a TP topic at this point.

 

HINT! HINT! :lol:

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Are these the PPC750FX and PPC750GX based iBooks?  I never followed the iBook line much.

 

I am all for an effort to salvage as many 750FX and GX chips as possible.

 

However, there are issues with putting them on ZIF cards...

 

The easiest and probably cheapest thing would be to replace the CPU  on existing slower ZIFs (266 ZIFs would be a good choice as just about hte slowest thing around).   However, that won't work.  The 750FX and GX have a different pinout than eariler PPC750s.

 

Soooo, new ZIF cards would need to be created.   Challenging.  Perhaps even daunting.   Certainly possible.   The hard part would be finding the Pin grid array that goes on the bottom of the ZIF card.   I looked for those once, and as far as I can tell, they were never in anyone's public catalog and they're probably long out of production at this point.    Getting a new batch made would mean either high unit prices or a large up front order, or both.   Or  a really great stroke of luck and the locating of the 10,000 units that never got used and have thus far been overlooked by the gold reclaimers.

 

Desoldering is not particularly difficult.   Reballing and resoldering is more challenging, but some forum members have accomplished it with G4s with larger pin counts.    

 

Again, if we're talking about the PPC750fx/gx, the bus multiplier is set with software.   There may be pins to set the boot multiplier, but those could be hard set to an "always works" value and then let the user adjust with software settings.

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Are ZIF Sockets with a higher pin count that might be used on a pinout conversion PCB available? I'm thinking DOA PC MoBo reclamation for some reason or other.

 

edit: heck, are pin grids of some form factor available to gang up on pinout adapter PCB for the CPUs? At this point, who even needs ZIF on an old 266MHz card? Clueless here, I'm living in a .1 pitch world. I'm heading back into my cave now. ::)

Edited by Trash80toHP_Mini
I'm an idiot. :-/
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Just to add a little background information:

 

Original PPC750 (includes PPC750L):   No internal L2 cache.   Special pins on chip package to interface directly with L2 cache chips.  Speeds to 500 MHz (rare)

PPC740:  Introduced with PPC750.  Essentially a PPC750 with the external cache interface removed.  No front side L2 cache possible.  Meant to be pin compatible with PPC603, so a drop in upgrade, but loses the huge benefit of the fast L2 cache.

 

PPC750CX:   First G3 with onboard L2 cache.  Onboard 256KB L2 cache.   Pinout change because no need for external L2 interface.  Speeds to 500MHz.

PPC750FX:   512KB onboard L2 cache.    Speeds to 900 MHz.

PPC750GX:  1MB onboard L2 cache.   Speeds to 1100 MHz.

 

If would be really cool, if when the introduced the CX, FX and GX they had made them pin compatible with the PPC740, as the 740 was described as pin compatible with the PPC603...

 

The PPC750FX and GX are (IIRC) pin compatible.  I think there's a small change between the CX and FX, but the memory is hazy and I'm not going to go chasing the answer right now.

Edited by trag
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Third-party G3 750GX ZIFs were made at speeds up to 1.1ghz so I'm sure it would be "technically possible" to manufacture new ones using chips removed from dead iBooks but, yeah, as Trag points out:
 

2 hours ago, trag said:

The 750FX and GX have a different pinout than eariler PPC750s.

You can't just take existing ZIFs and swap the slower CPU, you'll have to build a new ZIF carrier.

Given that the PowerPC 7400/7410 (aka, G4) *is* pin compatible with the G3 ZIFs upgrading to that CPU is a more practical proposition, even if it's ultimately less satisfying. (Given the lower clock speed ceiling of around 500mhz.)

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I took a look at Everymac.  It looks like Apple used the 750FX in the iBooks, but never the 750GX (unless there was a quiet upgrade at some point).   Searching for old stock of chips, there are 9 "affordable" 750FX rated for 600 MHz at about $39 each.   I also found 10 750GX at 1.1GHz, but they're north of $130 each.   But new old stock would certainly be easier to manage than reballed reclaimed chips.   But the numbers of affordable units are very limited.

 

And we still don't have a source for the PGA.

 

jt, ultimately, and ZIF card or stack of adapters one might build, needs to end in the proper, IIRC, 19 X 19 pin grid array, because that's the socket that's on the Beige G3 board and a host of related machines and adapters.  

 

As far as I could tell, when I researched this several years ago (but still too late for the 750GX to still be a live part) Mill Max made the PGAs.   And the pin array is a surface mount, probably something like BGA to pin part.   The pins don't go through the circuit board.  They terminated, probably in tiny heads that are balled and surface soldered to the underside pads of the ZIF card.  

 

So the ZIF card has BGA parts soldered to both the top and the bottom.

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1 hour ago, trag said:

I took a look at Everymac.  It looks like Apple used the 750FX in the iBooks, but never the 750GX (unless there was a quiet upgrade at some point).

I'm sure that's right. I just mentioned the GX because it happened to be the chip that ended up in the very fastest G3 upgrades and I couldn't remember offhand if the G3 iBook ever made it over 1Ghz; it did indeed top out at 900mhz.

 

1 hour ago, trag said:

But new old stock would certainly be easier to manage than reballed reclaimed chips.

How's the wild stock of 7400/7410's holding out? It seems like there could still be a market for converting G3 ZIFs into G4s, albeit a small one? (Of course, I haven't checked what G4 ZIFs go for on eBay.

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I just lucked into a lot of 7 PPC750GX in the 933MHz grade, which I think PowerLogix used on their 1.1GHz cards.    So, if someone finds that pin grid array laying around in a bin at an old electronics store, then I can add it to the list of things that I never seem get any closer to doing.

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You know, PowerLogix already did this with their Pismo G3 upgrades. They took the stock card, soldered on an adapter board, then soldered either a 750FX or GX on top of that (the 750FX, 750GX, 750FL, and 750GL are all pin compatible with eachother), and gave you a smaller heatsink to make it all fit. Here is a blog post of someone showing you how to mod the stock Apple cooler for better thermals, which has some good photos of said adapter board. So yes, it should technically be possible to do this, if one was to make an adapter board. I've heard through the grapevine that someone on this forum is looking at doing that, but I'll let them announce that if that is the case.

Edited by Daniël Oosterhuis
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About that pin compatibility:

 

Found an interesting chart: https://www.okqubit.net/ppchikaku.html Looks like these could be signal, if not pin compatible with the 603e:

 

Motorola XPC740P

IBM PPC740L PID-8p

 

Both are in the same 255-pin CBGA package as the 603e on the boards in several PowerMacs and PowerBooks.

 

Thinking about a multilayer 240-pin CQFP to 255-pin CBGA in order to try reworking some redundant PowerBook 1400 processor cards to G3 400 as a first go round.

 

The QFP to BGA adapter looks OK in my head. ISTR seeing something stupidly expensive to do this kind of prototyping conversion way back when? I wonder if it's a workable notion for a multilayer SEEED  square or even possible?

 

Clock multiplier would be handled on the adapter so I don't have to locate the friggin' things on my 2300c mobo. :ph34r:

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Here we go:

 

Quote

The PowerPC 740 is completely pin compatible with the older 603, allowing upgrades to the PowerBook 1400, 2400, and even a prototype PowerBook 500/G3. The 750 with its L2 cache bus required more pins and thus a different package, a 360-pin ball grid array (BGA).

 

Wikipedia, but I've seen this info many times in legit sources. [:)]

 

 

Edited by Trash80toHP_Mini
what-ever
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6 hours ago, Trash80toHP_Mini said:

Here we go:

 

 

Wikipedia, but I've seen this info many times in legit sources. [:)]

 

 

The 603/604 and 740 compatibility isn't exactly new, @LightBulbFun has been planning on doing such an upgrade for a while, I think he indicated it once in the iMac G3 -> G4 thread. 

Also, the Wikipedia pages on PowerPC are fairly solid, the main guy working on them, Henriok, knows his stuff. He's also the one who made all the very nice PowerPC CPU renders shown on those pages. 

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Yeah, that compatibility thing's been nagging at me from about 2002 or 2003, which is a lot of years to have something on my mind.

 

Dr. Bob over on 'fritter said I was crazy for thinking the 2300c and the 1400 were peas in a pod. He finally came around, but convinced me that it was crazy talk to try a G3 Duo hack (back then) and now memories of those $750 prototyping adapters are beginning to translate into something that might be cobbled together to have made in a Chinese PCB Fab.

 

BGA pin compatibility is a given, but that's not the biggie. It's adapter translation from BGA to the QFP pads on NuBus architecture PowerBook boards that will be the brass ring. IIRC, the 5300ce board is BGA to begin with, if so, that's one dream machine for 400MHz G3 rework right there! [:D]

 

Glad to hear that the technical stuff on PowerPC there is good. The MD/PhD rug rat says the science on Wikipedia is very well maintained, but I've found some of the history to be hit or miss. It's tough to take it seriously when the same-o-same-o winds up in an article because it's generally accepted, but not quite accurate. Most of that's in military history from the first half of the last Century, but it makes me wonder about the rest.

 

edit: could be the 3400c that's BGA, dunno, should have been in bed a couple of houres ago  .  .  .  zzzzzzzzzzzzzzzzzzzzz

 

Edited by Trash80toHP_Mini
oopsies
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