@Geri

I have a MicroA1 which has a cracked G3 die on the module. I also have an XE G4 that is broken in someway, not sure if it's the module or motherboard. So...

My intentions are to probe out anything I can from CPU to Megarray, switches, etc. that would be useful to know. And I got an old Mac of some kind for a replacement G3 CPU. I don't have anything good to replace G4 with, I have a handful of various older Mac modules to also probe out the Megarray, and try to map the differences for an adapter from Mac modules to Xe/uA1 motherboard, and perhaps to get a template for a totally new Xe/uA1 module PCB in Eagle.

I have an IR preheater platform, an air tool, but not a stand/holder for it. Also need some reball kit stuff to practice on Mac modules, and maybe a few more Mac modules to sacrifice. And someplace to set all this up at. (I have a home office where I want all this, which currently looks like a warehouse had a bomb go off in it)

Can anyone suggest an approprite Mac model to test Mac CPU modules in before/after I mangle them? I don't have one of these.

But, my usual problem is a perpetual lack of time to do anything fun. :/

Last edited by billt on 28-Aug-2015 at 02:08 PM.
Last edited by billt on 28-Aug-2015 at 02:04 PM.

_________________
All glory to the Hypnotoad!

@olegil

Quote:

chrisot already did this exercise, but he failed to document it for the rest of us.

That only tells me that it needs to be repeated at least once.

_________________
All glory to the Hypnotoad!

@billt

I've also imagined a Mac Megarray to A1 converter. But I also imagine that it could be more work to design a board that wedges in between and reroutes the traces to the correct place.

I also wonder why the standard layout wasn't chosen" Or is it that Apple had their own layout and a patent to match preventing anyone else using the layout?

@Hypex

Quote:

Hypex wrote: @billt I've also imagined a Mac Megarray to A1 converter. But I also imagine that it could be more work to design a board that wedges in between and reroutes the traces to the correct place. I also wonder why the standard layout wasn't chosen" Or is it that Apple had their own layout and a patent to match preventing anyone else using the layout?

Nice Idea, may or may not be that hard. I wonder?

@billt

Some useful information:

I had the meg-array replaced aswell as the CPU.

Meg-Array:
FCI 84500-102LF plug (motherboard).
FCI 84502-101LF receptacle (cpu daughterboard).

These are exact replacement parts, and are available from;
http://uk.farnell.com/

Farnell part numbers:
1623925 - FCI 84500-102LF PLUG, BGA, 300WAY
1623936 - FCI 84502-101LF RECEPTACLE, BGA, 300WAY
1455489 - OMRON SWITCH, DIP, SMD, 4WAY

Preforms is the best way for re-balling, it eliminates errors.

Then there is stencils with solder balls, this method works best with a oven.

If you are highly skilled you can use a dispenser, very difficult but is possible (not recommended).

Last edited by delshay on 29-Aug-2015 at 07:30 PM.
Last edited by delshay on 29-Aug-2015 at 07:26 PM.

_________________
The Machine: Bride Of The Pin•Bot by Williams Electronics

@billt

Quote:

billt wrote: @olegil Quote: chrisot already did this exercise, but he failed to document it for the rest of us. That only tells me that it needs to be repeated at least once.

I would attempt a repeat on 1 of my spare modules if I could find what was done by Crisot. Unfortunately I have not been able to contact him.

Last edited by busytech on 30-Aug-2015 at 07:00 PM.

@QuikSanz

I wonder too. Bit more complex than a PC floppy to Amiga or CF to IDE adaptor I suspect. Possibly pulling a CPU off a Mac card and soldering it to an A1 module may be easier.

Last edited by Hypex on 31-Aug-2015 at 08:42 AM.

@Hypex,

But wouldn't it be great to be able to swap out different Mac CPU's and check performance differences? I know, dream on...........

@QuikSanz

Well, if it's possible to reverse-engineer the pinout for an adapter, it's possible to reverse-engineer the CPU card in full and make new ones. I think this would be more useful, as EMC wise a CPU on a daughter board on an adapter board on a mother board is not the best idea. Chances are you'll end up limiting the FSB to 100MHz in the process. Much better to make new CPU boards which support the extra pins also, to make conditions as good as they can be.

The actual work involved in the design is more or less identical, given that megarray is a BGA package just like the CPU. Using modern technology it shouldn't be very expensive.

_________________
This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.

@olegil

I see 1.0, 1.27 and 1.42 GHz 7447A are in stock, though upper frequencies have an MOQ of 44 units. Actually doable if someone were to do this.

So get to the net tracings, boys and girls

_________________
This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.

http://lowendmac.com/reviews/08rev/maxpower-1.8-ghz-single.html

_________________
The Machine: Bride Of The Pin•Bot by Williams Electronics

@delshay

First step is done. I have just received the 3 faulty modules.



I did plan to use a 7447A G4 from a mac mini, but from what I have read, I do not think they would be compatible since they have 360 ball connectors and the original 7455 has 483 ball connectors.

Last edited by busytech on 01-Sep-2015 at 01:12 AM.

@olegil

Quote:

olegil wrote: @QuikSanz Well, if it's possible to reverse-engineer the pinout for an adapter, it's possible to reverse-engineer the CPU card in full and make new ones. I think this would be more useful, as EMC wise a CPU on a daughter board on an adapter board on a mother board is not the best idea. Chances are you'll end up limiting the FSB to 100MHz in the process. Much better to make new CPU boards which support the extra pins also, to make conditions as good as they can be.

Indeed. Every additional connector and the longer traces just makes things worse.
And by the way one could also add a faster L3 cache (DDR) than mounted on some of the original G4 CPU modules (SDR only).

I also wonder, if the G4 CPUs on Apple CPU cards are hardwired to work in MPX bus mode. The A1 northbridge only supports the 6xx bus mode, so that would likely prevent the direct use of an Apple CPU card, too.

Quote:

So get to the net tracings, boys and girls

I would like, but I don't have a broken spare CPU module.

@busytech

Quote:

busytech wrote: I did plan to use a 7447A G4 from a mac mini, but from what I have read, I do not think they would be compatible since they have 360 ball connectors and the original 7455 has 483 ball connectors.

Yes, the 7447A misses the L3 cache interface. I guess a 7457 is the only direct faster replacement for a 7455.

A new CPU module should definitely come with a 7448 and its huge L2 cache (no need for an L3 cache anymore)!

Last edited by Geri on 01-Sep-2015 at 09:14 AM.

_________________
A1SE: G3@600MHz, 2GB, 1GBit network card
A1XE: G4@933MHz, 2GB, refitted AC'97 codec
microA1: G3@800MHz, 1GB

- A1 Linux support -

@busytech

I meant on a NEW PCB, man.

@geri
Quote:

A new CPU module should definitely come with a 7448 and its huge L2 cache (no need for an L3 cache anymore)!

A valid point. 7448 are also in stock, roughly the same price for the same frequencies.

Last edited by olegil on 01-Sep-2015 at 11:14 AM.

_________________
This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.

Before attempting another CPU, look at PDF doc of both old & new CPU, just because it has the same ball count does not mean it will work.

What about firmware, will a new firmware be required to support another uprated CPU.

_________________
The Machine: Bride Of The Pin•Bot by Williams Electronics

@delshay

Quote:

delshay wrote: What about firmware, will a new firmware be required to support another uprated CPU.

As far as I know 7457 CPUs (the only viable upgrade IMHO) already work with the current firmware. A1's U-Boot version doesn't support any DMA operation, which would require proper CPU cache flush operations and the size of the caches should be the main difference between the 7455 and 7457.

_________________
A1SE: G3@600MHz, 2GB, 1GBit network card
A1XE: G4@933MHz, 2GB, refitted AC'97 codec
microA1: G3@800MHz, 1GB

- A1 Linux support -

@Geri

If someone really wants a 7448, I think this would be the easiest one to put on a new PCB. All we need is the pinout listing of the megarray connector. A 360 ball BGA with 40 NC pins isn't very difficult to use in 2015

Ah. Lower core voltages than what is supported on the XE. Dang. So would need additional regulators. Not difficult, just a hassle. 1.244V and 1.34V are useful for 1.4 and 1.7GHz 7448, the others are simply too high so would blow something.

Last edited by olegil on 03-Sep-2015 at 02:04 PM.
Last edited by olegil on 03-Sep-2015 at 02:01 PM.

_________________
This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.

@olegil

I have now ordered some powermac 1.25 GHz G4 dual boards for cpu removal. I am now having difficulty finding specs online for what the vcore should be the 7455 at various frequencies.

Last edited by busytech on 03-Sep-2015 at 08:10 PM.

@busytech

Depends on chip revision as well as frequency:

http://www.freescale.com/products/archived/host-processor:MPC7455?fpsp=1&tab=Documentation_Tab#nogo

1.3, 1.6 or 1.85 depending on chip marking (see hardware specifications plus the 4 addendums).

Oh and please map out the traces from BGA to MegArray while you're at it.

Last edited by olegil on 04-Sep-2015 at 08:39 AM.

_________________
This weeks pet peeve:
Using "voltage" instead of "potential", which leads to inventing new words like "amperage" instead of "current" (I, measured in A) or possible "charge" (amperehours, Ah or Coulomb, C). Sometimes I don't even know what people mean.