Hello,

This may be as simple as looking up a few datasheets.  But someone
knowledgable in this area may know an even easier way of solving this.

I need help identifying a CPU core.  
Here is a picture of it: 
https://netfiles.uiuc.edu/mantey/www/D411/D411_overview.jpg
So the question is: What CPU core is it?

The ROM is 512x8bit
The RAM is 32x4bit

This tells us the instruction size is 8bit and the ALU is probably
4bit.  I doubt the memory sizes will help identify the core, since
there's no reason they couldn't be changed, but I included it just in
case.

More info about the IC: 
Nintendo used it in designs from at least 1991 (and possibly all the
way back in 1983).  While, not conclusive evidence, there are some
schematics which label the pins as PA0, PA1, PA2... PB0,PB1... etc
like Sony does (Sony collaborated with Nintendo quite a bit back in
those days).

If you're not sure how to continue, you can purely guess, and I can
confirm.  The ROM is known:
picture - https://netfiles.uiuc.edu/mantey/www/D411/D411_dash_ROM.jpg
data - https://netfiles.uiuc.edu/mantey/www/D411/D411_ROM.txt

So if you guess, and give me a document containing the instruction set
for that CPU core, I should be able to confirm it. (Although I'm not
certain in what order the 1's and 0's in that rom txt file group into
bytes.  But I know the bitlines are verticle, and the collumn decoder
chose 1 each 8 adjacent lines, so the bits for 8 bytes are
'interleaved' into one rwo.  There are only a few reasonable
possibilities for the order of the bytes in this array, so that
shouldn't be a problem.  
So, seriously, feel free to make educated guesses.)

I can take more pictures or look closer at something if need be.  If
the pictures really aren't any help this just boils down to educated
guesses by looking at:  What 4-bit CPU cores using 8-bit instruction
sets were made before 1991 (and possibly before 1982)?
...and then finding the instruction set (so the guess can be confirmed).

Here's some 4-bit Sony CPUs with 8-bit instruction sets (don't know
the introduction date of the CPU core though)
CXP40* or CXP50*
http://www.sony.co.jp/~semicon/english/90230.html
That would be my educated guess, but I'm not sure where to look for
the instruction set.

If you need me to do anything more to help, let me know.