Unknown TI logic series

[Brent Hilpert]

On 2010 Dec 19, at 9:53 AM, Rick Bensene wrote:

> While this posting doesn't address the SN14xx-chips the original poster
> queried about, there is another machine that I have that has some
> TI-made SN12xx chips that I was able to find the story of that may be 
> of
> interest to others.
>
> The Friden 115x (Printing) and 116x (CRT Display) calculators use three
> interesting TI   chips that have SN12xx part numbers that I know to be
> custom chips made for Singer by TI.
>
> The Friden 130/132 calculators, the predecessors to the 115x/116x 
> lines,
> didn't have adders in the classic sense.  These machines are all based
> on counters.  The original architecture of the EC-130 was based on a
> series of four five-bit counters that were interconnected in different
> ways (by mostly gating logic) to allow them, by counting up and down, 
> to
> perform the math operations.    After the 130 was introduced, in the
> process of developing the EC-132 (which added square root), it was
> realized that all of the functionality could be done with three 
> counters
> rather than four, and a rework was done of the EC-130 boardsets to use
> this realization to reduce the part count, and thus the manufacturing
> cost.  A few EC-132's were also made with the four-counter 
> architecture,
> but soon into production the EC-132 was also changed to the
> three-counter design.  Each of the three counters had a slightly
> different  logic design.
>
> The goal of the 115x/116x calculators was basically to shrink the
> machines down by using IC logic rather than discrete transistors.
> These machines were implemented using a mix of small-scale DTL and TTL
> devices.  Friden didn't seem picky about vendor...there are chips made
> by Signetics (7400-series TTL), Motorola (MC8xx DTL), TI (7400-Series
> TTL, SN158xx DTL) all in 14 & 16-pin plastic DIPs.
>
> Along with all the SSI devices, there are three 24-pin MSI devices, 
> part
> number SN1286, SN1287, and SN1288.  These chips, which were custom made
> for Friden by TI (this is mentioned in discussions I've had with one of
> the engineers that worked on the development of the machines), 
> implement
> the three counters.
>
> Is it possible that the SX12xx-series TI part numbers were for custom
> devices?
>
I can't find mention of the SN12xx numbers, but together with the 
SN12xx a vague correlation I see in the 1969 TI databook is that 
SN1<anything> are designs or numbers which do not originate with TI, 
that is, they are either custom or design/numbering originated with 
another manufacturer:
    SN179xx 900/800 series RTL from Fairchild
    SN178xx   "       "     "    "      "
    SN159xx 900/800 series DTL from Fairchild
    SN158xx   "       "     "    "      "
    SN154xx custom digital logic circuits