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IBM 5170 - how to find model number?

Jorg

Jorg

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After a long quest, I was finally able to obtain a nice IBM 5170 AT.

Now I wonder, what exact model it might be. The label on the back only says IBM 5170. There are a lot of numbers on the motherboard, but not something like -319.

Could anybody help me with it?

Some features if found out
- Bios dated 1-10-1984
- old style ("type 1") motherboard
- 84 key keyboard (XT- like function keys on the left)
- it runs at 6 mhz
- 20 meg HD

where should I look?
 
It was a lab machine so it was extended a bit - AD/DA converter, three parallel and two serial ports, one memory board, one EMS memory board - it was full of cards :) .
I took out the memory card and then I had 512 K, both banks on the motherboard are full.

It seems to be a -099 !
 
Hmm. how do is see if its piggy-back? Underside of motherboard? (its dark in there, and I wasn't planning on removing the HD..yet. Want to take a closer look at the CPU, so I think I might have to.

And.. joy joy.. its has a 80287!

(And, no sorry..I want to keep it for the moment..)
 
Simply, where you see the banks of RAM on the motherboard, take a closer look at the chips: if you see two chips soldered together, one atop of the other, then that means you have piggybacked chips.

When the 512KB AT's were first being made, IBM had a massive suplus of 64K RAM chips to get rid of, and not so many 256K chips, so they wanted to used up all of the 64K chips first. Ergo, to use up all of the 64K chips, they used the Type I motherboard, which originally only had 256KB of RAM, and soldered another array of 64K chips atop, doubiling the RAM on the system to 512KB.
 
Hey, you're right, there are two chips on top of each other! So yes, I got 512K of piggy backed ones.
 
I have a Type 1 5170-099 with the piggyback chips also and I'm looking for the correct co-processor to use. You mentioned you had a co-processor - do you know what type it is (numbers on the co-processor chip?

Old PC Man
 
The type of coprocessor used in the IBM PC AT's were the 80287's, and according to my knowledge (which is limited in this perticular area) any speed of the processor could be used, but in my opinion the 6MHz model (80287-6) would be the best choice, as the slower model, the 3Mhz (80287-3), would have to be overclocked slightly as to what the board designates as the coprocessor clock speed - 5.77MHz, I bileve, which would mean it would run hotter.

Coprocessors always have to run slightly slower than the main processor, due to clock and speed issues. This actual speed varies from machine to machine, but in the IBM PC AT, I forget if it is either 5.77MHz in both 6 and 8MHz AT models, or 77% of the processor speed of either model of AT.

Now this information is probably not totally accurate. The best bet would be to double check with proper documentation, if you could find it. Best bet would be to find or track down someone who has a PC AT users manual.
 
No problem opening the case for that, but it would help to have an idea where its located. I recognize it when I see it, but do I have to remove the harddisks or floppies?
 
Jorg said:
No problem opening the case for that, but it would help to have an idea where its located. I recognize it when I see it, but do I have to remove the harddisks or floppies?
Click to expand...

What, the co-processor?

On the Model I motherboards of the PC AT, they were loacted near the upper right of the motherboard JUST below the keyboard connector. The co-processor is a DIP chip about 3/4" wide and 2" long, with a gold square section on the top that identifies the chip in some way.

If you do not see the chip but an empty slot, then you have no co-processor.
 
Its there allright, it just had some strange folded clip over it so I didnt see it at first. Cant read the model due to lack of light right now.
 
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