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8087 getting hot.

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Dmitriy Krotevich

Experienced Member
Joined
May 14, 2013
Messages
107
Location
St.Petersburg, Russia
Today I received the 8087 math co-processor. I installed it into the socket and it was recognised by the system:

IMG_6460.jpg

then i suddenly touched the chip and it appeared to be noticeably hot , so I turned the system off immediately.

Is it normal for this kind of hardware to become hot only after several minutes of uptime even without doing any calculations? What is the normal working temperature of 8087?
 
I get the same thing on my system, I bought a stick on heat sink for it.
 
Yes, it's normal for an NDP to get hot, particularly the early ones, such as the 8087. Cyrix made a CMOS 80C87, but good luck finding one.

The 8087 is far more complex internally than the 8088 and so dissipates a lot more heat. This is why the 8087 is packaged as a CerDIP and not a PDIP.
 
Chuck(G) said:
The 8087 is far more complex internally than the 8088 and so dissipates a lot more heat. This is why the 8087 is packaged as a CerDIP and not a PDIP.
Click to expand...

wow, didn't know that. So no threat of damaging the system board?

I was really scared because I thought I started to notice a "heat smell", you know, a smell like how a smoothing-iron smells. And only after I turned the system off, i realised it was a smell of a lamp I used to light up the board. ;)
 
Yeah, some of these old NMOS parts get quite hot. While the heat emitted from the chip is unlikely to hurt the board a heatsink wouldn't hurt. ;)
 
I have a Intel 80287, and boy it's very hot, I was concerned too about it, especially in the summer. I have thought about putting an heatsink on it.

I think RAM heatsink for modern PC's should do the trick. But then it loses all its esthetic beauty... It's so nice to see with the gold die and pins ;)

70° should the redline for temperature for both Fpu's, according to CPU-World:

http://www.cpu-world.com/CPUs/80287/Intel-C80287-3.html
 
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Ever seen a Cyrix 80C87 in the flesh? Or a picture? Or a datasheet? I've been trying to track one of these down for a long time, and it's as if they never even existed.
 
I've never seen one--I suspect they may have been sampled, but never produced. By the time Cyrix had silicon, the world had moved on to th 287 and soon, 387.

The 8087, as I recall, was a bear of a chip--more complicated than the 8086 and very cramped to the point where multi-value ROM was used on-chip (may have been the first instance of that). Yield was initially very low.

NEC in some databooks describe their own version of the 8087, but later specified the Intel 8087 as the compatible part. The V-series (V20/V30) had two coprocessor escape codes, but I've never run into the chip intended for the second code.

I suspect that cloning the 8087 turned out to be harder than anyone thought at the time.
 
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