Code listings for the I4004 or I4040

dwight dkelvey at
Thu Mar 17 21:51:22 CDT 2016

 The answer is no and yes.
You can not use the normal RAM instructions with the 4289. Still, one
can have RAM through the 4289. It would have no status RAM like the 4002s
but for a program that is written to use conventional RAM through the
4289, it has no more overhead than regular 4002s, for character RAM.
You'd setup a register pair as a pointer and a SRC, just like 4002s for
character RAM.
If you only need quick access of status RAM, you are stuck with 4002s
or, create your own circuits.
So, I wouldn't say yes and no, I think no and yes is the answer.
I did look up to see if 4008/9 recognize the RPM. The 4040 shows
WPM for both 4289 and 4008/9 but only shows RPM for the
4289. I take that to mean that the 4008/9 doesn't support the
RPM, even with the 4040 processor.

From: cctalk <cctalk-bounces at> on behalf of Eric Smith <spacewar at>
Sent: Thursday, March 17, 2016 1:23 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Code listings for the I4004 or I4040

On Thu, Mar 17, 2016 at 1:18 PM, dwight <dkelvey at> wrote:
>  The 4289 can be used for RAM with the 4040, using the WPM and RPM. It can be used
> on the 4004 but it is limited to WPM only.

I know about that; what I was asking about was whether the 4289 (or
4008/4009) could replace "normal' 4002 RAM. I think the answer is

> In any case, please don't erase the EPROMs, thinking they are blank.
> I offer my services to read them. Also, there may be someone closer
> to you that can extract the data.

I can read them.  Or rather, I could if I had them.  The sockets are empty.

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