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br44
May 6th, 2017, 10:15 PM
Hello

I have been waffling back and forth and I have decided to change out the processor on my IBM 5150 to something close to what it would have had out of the factory. Currently the computer has a 286 speedup board that I want to remove (and sell to a lucky bidder).

I am not entirely sure what CPU to put in there instead. I do not have to have it exact I just want to get close.

Looking on ebay I come across three options

AMD D8088
Intel P8088
Intel D8088

There is not a whole lot of price difference between them so which would be best or does it even matter? Will any of those processors NOT work? Will I see any performance difference between them? I know there is a difference between the P and the D intel chips... something about plastic vs ceramic? Any suggestions I haven't mentioned yet?

I know I will be losing some performance with the "downgrade"... but in all honesty if I am going to run software that NEEDS that speed I would be better off getting a real dedicated IBM AT computer instead of trying to push this poor 5150.

Thanks

modem7
May 8th, 2017, 03:31 AM
I know there is a difference between the P and the D intel chips... something about plastic vs ceramic?
Yes. The package type. For the 8088, P=plastic and D=ceramic.


Looking on ebay I come across three options
AMD D8088
Intel P8088
Intel D8088

There is not a whole lot of price difference between them so which would be best or does it even matter?
I have seen them all used on 5150 motherboards.


Will any of those processors NOT work?
No.


Will I see any performance difference between them?
No.

What would I choose? For me, it would depend on the motherboard.

For example. On a 5150 motherboard that I am repairing now (appears to be dated 1984), IBM has used AMD as the maker for the 8088/8255/8237/8253 and ROMs. If the 8088 was missing, an AMD 8088 makes sense to me, but only from a visual perspective.

For example. On a very early 5150 motherboard, I would choose an Intel D8088.

br44
May 8th, 2017, 07:30 AM
Yes. The package type. For the 8088, P=plastic and D=ceramic.


I have seen them all used on 5150 motherboards.


No.


No.

What would I choose? For me, it would depend on the motherboard.

For example. On a 5150 motherboard that I am repairing now (appears to be dated 1984), IBM has used AMD as the maker for the 8088/8255/8237/8253 and ROMs. If the 8088 was missing, an AMD 8088 makes sense to me, but only from a visual perspective.

For example. On a very early 5150 motherboard, I would choose an Intel D8088.

This is a later version of the 5150 so I will be going with the AMD.

Thanks :D

KenEG
May 8th, 2017, 04:53 PM
I have a couple that I removed from PCjrs that I would sell cheap. They are the basic 4.77 MHz chips.

vwestlife
May 8th, 2017, 06:44 PM
There was also a NEC 8088 (just a plain 8088, not a V20). My dad's IBM 5155 Portable PC came with one.

http://canoro.altervista.org/cpu/galleria/nec/8088/necd8088dmio.jpg

Chuck(G)
May 8th, 2017, 08:37 PM
The NEC license with Intel to produce 8088s spawned a lawsuit by Intel when NEC came out with the similar, but faster V20. I believe that Intel lost that one--and got a lot more draconian on their licensing agreements.

vwestlife
May 8th, 2017, 09:42 PM
The NEC license with Intel to produce 8088s spawned a lawsuit by Intel when NEC came out with the similar, but faster V20. I believe that Intel lost that one--and got a lot more draconian on their licensing agreements.

Intel did lose that case, because the court ruling determined that CPU microcode could be protected by copyright just like computer software, but the V20 was an emulation of the 8088 rather than a direct copy of it. But the ruling led to a later court case against AMD regarding the 386, as explained here:

https://books.google.com/books?id=tehpiERiUNAC&lpg=PA15&pg=PA15

(When the book says "80 x 86", it's a formatting error; they mean "80x86".)

Chuck(G)
May 8th, 2017, 09:52 PM
I remember that one well. Intel saying that NEC pirated its 8088 microcode for the V20 was facetious on the face of it--internally, the processors are quite different and the instruction set implemented by the V20 is more of an 80186 type than an 8088. Still, lawyers have to make their daily bread.

At this point, with the explosion of mobile devices, I wonder if the x86 architecture implementation/emulation may have finally seen the sunset on the horizon. ARM has made great inroads in this field--and I wonder if even RISC-V will pose a threat.

The next decade should be interesting.