Slightly puzzling G4 CPU, is it a normal 7400?

amedias

macrumors regular
Original poster
Feb 9, 2008
186
156
Devon, UK
I've been digging through some spares in boxes I had and happened upon a G4 processor that I bought about a decade ago when I was rebuilding a Sawtooth, as it happens a GE Dual processor card landed in my lap shortly after I bought this one so I never actually used it.

I was 99% sure I remembered it being a 400Mhz unit and was idly contemplating what to do with it so I looked for some markings to confirm, this is where it got puzzling....

Every single G4 I have ever seen in the flesh, (which is probably only about 30-40) has been clearly marked up on the die, and easy to identify. This one not so much.

I've attached pics although I couldn't get the markings on the die visible with my phone camera. The markings are smaller than normal, so small I can't read them without a magnifying glass and don't follow the normal format I'm used to, it reads:

YHA07008TB
LYLY9JX
0 06-12

The die is NOT square like most of the lower clocked 7400s I've encountered, it's decidedly rectangular but doesn't look as small as the 7410 dies I've seen.

The rest of the daughter card is an entirely normal OEM Apple part with the c2000 markings, and the bar code markings indicate a 400Mhz (INDONESIA P10 400).

So what is it? Is it just another Motorola 7400 variant without the normal markings? Hoping some of the more learned PowerPC folks might know!

I don't really want to go and pull apart my only compatible Sawtooth to plug this in at the moment to investigate further but will if needs be!
 

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B S Magnet

macrumors 6502
Dec 5, 2018
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don’t read my status message
I've been digging through some spares in boxes I had and happened upon a G4 processor that I bought about a decade ago when I was rebuilding a Sawtooth, as it happens a GE Dual processor card landed in my lap shortly after I bought this one so I never actually used it.

I was 99% sure I remembered it being a 400Mhz unit and was idly contemplating what to do with it so I looked for some markings to confirm, this is where it got puzzling....

Every single G4 I have ever seen in the flesh, (which is probably only about 30-40) has been clearly marked up on the die, and easy to identify. This one not so much.

I've attached pics although I couldn't get the markings on the die visible with my phone camera. The markings are smaller than normal, so small I can't read them without a magnifying glass and don't follow the normal format I'm used to, it reads:

YHA07008TB
LYLY9JX
0 06-12

The die is NOT square like most of the lower clocked 7400s I've encountered, it's decidedly rectangular but doesn't look as small as the 7410 dies I've seen.

The rest of the daughter card is an entirely normal OEM Apple part with the c2000 markings, and the bar code markings indicate a 400Mhz (INDONESIA P10 400).

So what is it? Is it just another Motorola 7400 variant without the normal markings? Hoping some of the more learned PowerPC folks might know!

I don't really want to go and pull apart my only compatible Sawtooth to plug this in at the moment to investigate further but will if needs be!
The green dot suggests it could be a swap-out of a previous processor.

I'm not sure how practical it might be to peel back just enough of the heatsink foam, but I have a hunch that it will read "IBM" and not "Motorola". If this is the case, it may look something like this:





If so, then it’s the IBM-manufactured version of the MPC7400.
 

amedias

macrumors regular
Original poster
Feb 9, 2008
186
156
Devon, UK
The green dot suggests it could be a swap-out of a previous processor.

I'm not sure how practical it might be to peel back just enough of the heatsink foam, but I have a hunch that it will read "IBM" and not "Motorola". If this is the case, it may look something like this:





If so, then it’s the IBM-manufactured version of the MPC7400.
Mystery solved I think, based on that pic the die shape and marking format is the same.

Ok so I need to do some research then as I thought they were always Motorola chips in these G4s at the lower clock speeds. I was aware of IBM being involved with trying to solve the supply issues but I thought that was for the 500Mhz parts, I never knew they shipped at the lower clocks. Every day is a school day!
 
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timidpimpin

macrumors 6502
Nov 10, 2018
461
345
Cascadia
I'm guessing the IBM G4's are pretty rare? Based on this chart from Wikipedia they only made a 400-500MHz 7400, so it must be an IBM. Every other G4 chip is a Motorola/Freescale.

 

amedias

macrumors regular
Original poster
Feb 9, 2008
186
156
Devon, UK
I'm guessing the IBM G4's are pretty rare? Based on this chart from Wikipedia they only made a 400-500MHz 7400, so it must be an IBM. Every other G4 chip is a Motorola/Freescale.

Just found that chart/article, don’t know why I didn’t think to check Wikipedia earlier!
 

LightBulbFun

macrumors 68020
Nov 17, 2013
2,129
1,946
London UK
I've been digging through some spares in boxes I had and happened upon a G4 processor that I bought about a decade ago when I was rebuilding a Sawtooth, as it happens a GE Dual processor card landed in my lap shortly after I bought this one so I never actually used it.

I was 99% sure I remembered it being a 400Mhz unit and was idly contemplating what to do with it so I looked for some markings to confirm, this is where it got puzzling....

Every single G4 I have ever seen in the flesh, (which is probably only about 30-40) has been clearly marked up on the die, and easy to identify. This one not so much.

I've attached pics although I couldn't get the markings on the die visible with my phone camera. The markings are smaller than normal, so small I can't read them without a magnifying glass and don't follow the normal format I'm used to, it reads:

YHA07008TB
LYLY9JX
0 06-12

The die is NOT square like most of the lower clocked 7400s I've encountered, it's decidedly rectangular but doesn't look as small as the 7410 dies I've seen.

The rest of the daughter card is an entirely normal OEM Apple part with the c2000 markings, and the bar code markings indicate a 400Mhz (INDONESIA P10 400).

So what is it? Is it just another Motorola 7400 variant without the normal markings? Hoping some of the more learned PowerPC folks might know!

I don't really want to go and pull apart my only compatible Sawtooth to plug this in at the moment to investigate further but will if needs be!
aye yeah thats a IBM 7400 :)

IBM did not want to make the 7400, but was forced to step in when Motorola had severe issues supply chips

as such the IBM 7400 is a pretty rare chip, if your vigilant you may see 1 or 2 CPU cards pop up with them, but otherwise, yeah nice find :)
 

amedias

macrumors regular
Original poster
Feb 9, 2008
186
156
Devon, UK
@LightBulbFun and @B S Magnet

Thanks for the info guys, always like learning something new about old PPC kit, and I have a bizarre particular like for 'rare but not worth anything' items so this makes me smile.

Now I just have to decide what to do do with it as it's currently homeless... maybe I should find a (another) Sawtooth board or mahcine to plug it into and join rest* of the PPC family that currently lives here :)

*
1x B&W G3 450 (OC'd)
1x GE G4 2x450
1x DA G4 533
1x QS 800 (currently 'dead')
1x QS 933
1x MDD 1.25
1x late '05 G5 2x2.0
1x 12in PB G4 1.5
2x 15in PB G4 1.0
1x 15in PB G4 1.33
1x 15in PB G4 1.5
 

amedias

macrumors regular
Original poster
Feb 9, 2008
186
156
Devon, UK
I would happily buy that IBM G4 if you're interested in selling. I have a thing for rare CPU's. Name your price if interested.
I would gladly *give* you the CPU if it’s really of interest to you but I’m in the UK so shipping would likely be costly?

EDIT - actually for small items seems not unreasonably priced, about £6 for an untracked slowish service
 
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timidpimpin

macrumors 6502
Nov 10, 2018
461
345
Cascadia
I would gladly *give* you the CPU if it’s really of interest to you but I’m in the UK so shipping would likely be costly?

EDIT - actually for small items seems not unreasonably priced, about £6 for an untracked slowish service
I would insist on giving you something for it, and also paying shipping of course. I'll send you a PM with my details and a fair offer for the CPU.