What is the chip with NEC 8427xx D7801G 105 markings?

[Sputnik]

What is this chip?

Does anyone know what IC this is? Could it be a MCU or what? Anyone with information or datasheets? Help needed, please! Included is a picture.

Following characters are printed on IC:
"NEC 8427xx D7801G 105"

Thanks
Sputnik

 

[golfbumb]

Re: What is this chip?

Yes it is a MCU, but it likely runs at around 2MHz. Yes, 2MHz. It is almost exactly 20 years old.

It is an NEC D780-1 which is an 8-bit CPU clone compatible with the 2x32 DIP package Zilog Z80 8 bit-CPU. That package was used in the mid 1980s.

8427XX is the manufacture date code. The first two digits are the year manufactured (1984), the second two are the week (27th) of the year. The XX would refine the date further, but is not used here.

 

[Sputnik]

Thanking you

Thank you, that is extremely helpful information, would you by any chance know if it is possible to reprogram it and, if so, would you (or anyone else) know where I could find the circuitry and software required?

Thank you
Sputnik

 

[golfbumb]

Re: What is this chip?

Reprogram it? No, you can't as it is an ASIC that got all of its characteristics at the time of manufacture. It was not a field programmable device -- other than bios, and through the operating system of course.

What you might be able to do is use it as an 8-bit microprocessor in its exact configuration. The operating system on these was called CP/M which was made by a company called Digital Research. (It was said that if the founder of Digital Research, Dr. Gary Kildall, was even slightly as aggressive as Bill Gates then Digital Research would be where Microsoft is today.) Digital Research is long gone (or was absorbed into something else). See https://en.wikipedia.org/wiki/Digital_Researchfor some history. Also, it may have been supported by one of the very early versions of DOS.

But if you want to do anything, you are probably going to have to program in assembly code. Finding a compatible C compiler could be very tough.

Sorry, I used to have an obsolete programmer's guide for the Z80 I'd had since I was a kid (which would have worked for the NEC of that class), but I tossed that out in 2000 during a move.

Personally, I would set it aside in your personal museum and start with a contemporary MCU or gate array. This pin configuration is obsolete, or at least I could not find it at https://www.zilog.com. I doubt NEC makes anything compatible anymore.