Code listings for the I4004 or I4040

Eric Smith spacewar at
Thu Mar 17 01:43:35 CDT 2016

On Tue, Mar 15, 2016 at 10:54 PM, dwight <dkelvey at> wrote:
> I've been scanning the web in search of any code listings for these processors.
> Does anyone have a stash of paper tapes or listings?

Unfortunately I do not, but I've recently become interested in such
things, as I have received from a friend's estate an old board from an
embedded system (possibly a cash register) which has a 4040 CPU.
Photos here:

The board also has the 4008/4009 memory interface, sockets for 16
1702s (I assume, though they are all empty), a bunch of TTL, a bunch
of hand-kludged stuff, and two 44-pin .156 pitch edge connectors (on
the same edge of the board).  It has all of *zero* 4002 RAM chips.
Maybe there were 4002 chips on another board.  The only marking on the
board, on both sides, is "MCS 4/4 N".

There are four strange-looking hybrids. Three of the hybrids have 22
pins with 600 mil row pitch, and are labeled (with stylized prefix




The fourth hybrid is a six-pin device with 300 mil row pitch, but
longer than a 16-pin DIP, and is labelled:


I suspect that the 751, 752, and 754 may be date codes, though the
5002A seems out of place.  My guess is that the primary purpose of the
hybrids was to make it difficult for competitors to clone the board.

For want of information on the board, I'll probably just remove the
4040, 4008, and 4009, and build my own system with them.

Would I be correct in thinking that the 4008/4009 (or the later 4289
that replaces them) only serves to interface to program memory, but
does not provide means to add RAM in the data address space?  (I know
that you can put RAM in the program space and write to it with the WPM
instruction, but that's nowhere near as convenient to access for

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