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8087 Upgrade Fail; Fake chip?

mcsew2k

Member
Joined
Apr 11, 2012
Messages
34
Location
California
My first ever 8087. I received it sealed in an anti-static envelope; seller insists it is new old stock. I don the proper anti-static strap and proceed to plug in the chip. I set the DIP to OFF (Block 1, Switch 2) and my system won't even POST. Does anyone know how I can check if this chip is a fake (without tearing it apart)?
 

Chuck(G)

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Jan 11, 2007
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38,856
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Pacific Northwest, USA
Doesn't sound as if you've got a good chip there. I assume that you did the usual checks; making certain that there are no bent pins and that the DIP is oriented correctly in the socket (i.e. not plugged in backwards or offset by a row).
 

mcsew2k

Member
Joined
Apr 11, 2012
Messages
34
Location
California
Yea, no bent pins and in the right way. I just pulled out my XT and the same thing, no POST. I used Buy-it-now on eBAY and didn't notice I was buying from Hong Kong until I was paying. Not worth sending back, but I want to see if I can figure out if it is an intentional fraud, or simply a bad chip.
 

Chuck(G)

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Jan 11, 2007
Messages
38,856
Location
Pacific Northwest, USA
The HK sellers are variable. Some are outright frauds, selling relabeled chips (I suspect that your 8087 isn't even one under the ceramic--it is a cerdip, not a plastic chip).

On the other hand, I've had some great experiences with HK sellers.

You have to be careful.
 

mcsew2k

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Joined
Apr 11, 2012
Messages
34
Location
California
I now have a 8087 that lets the system boot. Is there a program I can download that will test and/or exercise the 8087 chip?
 

modem7

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Joined
May 29, 2006
Messages
7,784
Location
Melbourne, Australia
Is there a program I can download that will test and/or exercise the 8087 chip?
CheckIt Diagnostics will check/test the 8087 maths co-processor.
The particular check/test is done during the 'System Board' test within CheckIt.
CheckIt refers to the maths co-processor as the "NPU" (numeric processor unit).
 

StowComputers

Member
Joined
Aug 11, 2011
Messages
35
Location
Stowmarket, UK
I remember fitting an 8087, and needed it for rendering. You could try a raytracing test with POV Persistance Of Vision, although I don't know if this software is still around. It knocked the rendering time of a picture of fractal generated islands in the sea from 12 hours without the co-processor to about 20mins with it. I remember being bowled over by that!
 

deathshadow

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Joined
Jan 4, 2011
Messages
1,357
although I don't know if this software is still around. It knocked the rendering time of a picture of fractal generated islands in the sea from 12 hours without the co-processor to about 20mins with it. I remember being bowled over by that!
POV-RAY is still around, though it's been a while since they provided 16 bit binaries.

http://www.povray.org/

3.1g was the last version to have official DOS builds.
ftp://ftp.povray.org/pub/povray/Old-Versions/Official-3.1g/MS-Dos/

3.5/later they dropped 16 bit OS support -- but it's matured into a real 3d suite when paired with modeling software like Moray, which is now free as the folks at Pov-Ray put together the means to acquire control of it.

Still fun to play with -- especially with 3.5/later supporting multiprocessing so that 20 minutes is down to a few seconds on a i7... though you can still crank the quality and scene complexity up to where some scenes take hours or even days on a modern system -- stuff that would have taken years at 8087 speeds.
 

mcsew2k

Member
Joined
Apr 11, 2012
Messages
34
Location
California
CheckIt Diagnostics will check/test the 8087 maths co-processor.
The particular check/test is done during the 'System Board' test within CheckIt.
CheckIt refers to the maths co-processor as the "NPU" (numeric processor unit).

I had an issue getting CheckIt onto a floppy that would work in the PC. To make a long story short, I was able to put in on a native 720 KB floppy using a DTK controller and it ran and passed my 8087 chip. Thank you for the help.

I only have Lotus 123 on catridges for the PCjr, but I know I have Borland QuattroPro. I will do some benchmark testing in the near future.
 

andykmv

New Member
Joined
Dec 9, 2014
Messages
3
they also made a huge difference with cad drawing manipulation/renderings!
 
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