2116 and other old memory chips

From: Richard Erlacher <edick_at_idcomm.com>
Date: Fri Jul 6 20:05:16 2001

I don't think the 2116's (now, this is from memory cells undisturbed in probably
20 years ... so be careful ... ) are much different from 2117's, which I've
routinely interchanged and mixed with 4116's.

The 2114's are single-supply 1Kx4-bit SRAMs, while the 2116's are dynamic and
3-rail. The single supply Intel 16-kbit DRAMs are the 2118's.

The TI number for the 2114's was TMS-4045 and other vendors had part numbers
similar to the 2114, e.g. 9114, 7114, etc. National had a 5290 instead of the
4116 designation, but the parts were similar. There are some "special" parts
that need to be noted, particularly the 4115, from Mostek. These were devices
the gate capacitance of which wasn't enough to hold their charge reliably for
the entire 2 ms refresh interval, so they had the special designation of 4115 to
indicate they required more frequent refresh, which often wasn't an issue, since
they were used in applications where they were cycled very frequently because of
video refresh or other system activities that cycled the row addresses faster
than the 2 ms per 128-byte cycle requirement of 4116's.

Intel's memory numbering was a mite confusing, as they had an old SRAM line with
numbers like 2115 and 2125, which were 1kx1 fast (15-25 ns) srams while the
2114's were slow 1kx4's. They had lots of numbers, and the numeric series
designation was often not at all indicative of the nature of the part.

I've still got quite a few 4116's (200 ns Tacc, mostly) that I'll donate for the
cost of shipping, to folks with REAL applications for them. I'm not interested
in shipping them in quantity to folks building pop-art with 'em, however, as
these work, and they don't make 'em anymore.

Dick

----- Original Message -----
From: "Louis Schulman" <louiss_at_gate.net>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, July 06, 2001 5:54 PM
Subject: 2116 and other old memory chips


> I am in the process of attempting to repair, with Pete Turnbull's
> invaluable guidance, an Exidy Sorcerer.
>
> The manual recites that the memory chips, depending on configuration,
> are 2104 (4k) or 2116 (16k).
>
> A casual perusal of chip sources shows that most begin their dynamic
> ram sections with 4116 chips. The only mention I have found of 2116
> chips is in a reference to the original IMSAI memory board.
>
> So, my questions are: Are 2116 chips 3-rail? Are 4116 chips
> equivalent? Does anyone have a source for 2116 chips, if they are not
> equivalent? What about 2114 static ram (used in the video section of
> the Exidy)? Same problems? Were they all three rail?
>
> A general lecture on the nature of old memory chips and their use and
> selection would be very helpful (hint to Tony Duell).
>
> Thanks, Louis
>
>
Received on Fri Jul 06 2001 - 20:05:16 BST