Here's the last one. It's an Intel 8742

http://www.ukcpu.net/Collection/Processors/In … 2/8742/8742.asp

Now try to sell them on ebay for 800 grand?

http://www.ebay.com/itm/C4040-ES-INTEL-CPU-RA … =item2c54ff09df

Just kidding. Nice collection! I hope you find some machines to use them in.

I wish old, rare CPUs would just show mysterously on my desk.

Oh, and the Cyrix 287XL is one of the best 287 co-pro's out there and not that easy to find. It will work with 386 motherboards that have a DIP coprocessor socket. The only one that beats it is the 287XL+. The 287XL+ will actually work with a Cyrix Cx486SLC. The earlier 287XL had some timing issues that needed to be worked out which is why the plus. They also have a 3/2 internal multiplier so they are capable of running at the same clock speed as the CPU.

Lol, I wish I could sell them for $800,000.00.
Thank you sliderider for the info on the 287XL, I was wonder what speed it could operate at.

I'm still a bit baffled by the D8742. It shows up as an 1.6-12MHz 8bit chip ( http://www.cpupages.com/store/index.php?id_item=870 ). The one on that page is listed as 1982 copyright though, and mine is 1977. I have very little knowledge of pre-286 chips so I'm lost on this.

I discovered that one of my brothers had found these in storage and figured that I'd like them so he snuck them in while I was at work. He has no knowledge of them except that he said that he used the cyrix 287 in a 386 and whatever program he used recognized it as a 387.

Oh and one other thing, I guess there's a chance that these came from some old government computers that a few relatives got their hands on back in the 1990s.

The D8742 is a microcontroller, not just a CPU. A microcontroller is more like a 'system on a chip', it has a RAM, EPROM and CPU integrated in one chip. The EPROM stores a small program, which the CPU will execute when powered on. Removing the sticker on top and exposing it to UV light will erase the program.

Thank you very much for that information.

Now I'm curious what it actually ran. Any idea what type of boards these used? Or would they work on an XT system?