Photo Request : 5500, 6500 and TAM Logic Board

[Phipli]

Hey folks, pretty please I'm interested to see the differences in what resistors are fitted on the 5500, 6500 and TAM. Could you take a photo of the following resistors and let me know what computer the board is from? Especially interested in the TAM.

Resistors of interest :

R165
R272
R273
R224

They're likely to be all next to each other.

 

[François]

FWIW, there’s a picture of a (dusty) TAM motherboard on iFixit.

Where are those resistors located? I couldn’t find them!

 

[Phipli]

FWIW, there’s a picture of a (dusty) TAM motherboard on iFixit.

Thank you

Where are those resistors located? I couldn’t find them!

Sadly I don't know - they might be under the heatsink - I have no idea.

 

[François]

They’re on the underside!? Here’s a picture of the underside of a 6500: it seems to me that R273 is near the bottom right corner of the square TI chip. (couldn’t find the other ones)

 

[Phipli]

R165 must be near the edge connector on the top, but I can't see it.

 

[François]

Should I get my TAM out of his box? I won’t tear it down!

 

[François]

Im curious, why are you interested in those particular resistors?

 

[Phipli]

Im curious, why are you interested in those particular resistors?

They set part of the machine ID. The boards are identical, but in part, these tell it what computer it is.

I wanted to see how they were different between the three machines, or if they were the same.

If all three were different, it would be easy to trick a 6500 or 5500 into making the TAM unique startup sound.

Discussion elsewhere means it is likely that the difference uses another method, plus nobody has provided info on the 5500 or TAM

 

[François]

Ooh, that’s interesting! It’s even interesting the other way around: if we could document the differences between a 5500/6500 logic board and a TAM one, it would allow to replace it more easily in case of failure or even make a 300MHz TAM!

I will have a 5500 LB in a few days, found one cheap. I sure will take all the necessary pictures!

 

[Phipli]

if we could document the differences between a 5500/6500 logic board and a TAM one, it would allow to replace it more easily in case of failure or even make a 300MHz TAM!

That's all pretty easy - you just remove the extra ports and fit a 6500 or 5500 board in a TAM. The only downside is unless we work out how they know they're different, it makes the wrong boot chime and reports itself as another computer. It would just work though. They're basically the same computer, just a different case and screen... And some missing ports.

 

[François]

Good to know that the differences are minimal. One day I’ll tear down my TAM just to see by myself how they Frankensteined the whole thing!

 

[dougg3]

Found them on my 5500's logic board. Luckily the components seem to be numbered fairly logically. They're all populated on the 5500. Large pictures attached...

• R165 is on the top between the edge connector and J16
• R224 is on the bottom near U16, Phipli's small red circle
• R272 and R273 are right next to each other on the bottom near U27, Phipli's larger red circle
• They are all 4.7k

 

[François]

They set part of the machine ID. The boards are identical, but in part, these tell it what computer it is.

I wanted to see how they were different between the three machines, or if they were the same.

If all three were different, it would be easy to trick a 6500 or 5500 into making the TAM unique startup sound.

Discussion elsewhere means it is likely that the difference uses another method, plus nobody has provided info on the 5500 or TAM

Is there a way to dump the ROM of these machines? Maybe their ROMs are different?

 

[Phipli]

Is there a way to dump the ROM of these machines? Maybe their ROMs are different?

The ROMs are all the same, I'm pretty sure