Unknown TI logic series
hilpert at cs.ubc.ca
Sun Dec 19 13:50:35 CST 2010
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
> 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
> 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,
> 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
> 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
> 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,
> 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),
> the three counters.
> Is it possible that the SX12xx-series TI part numbers were for custom
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
SN179xx 900/800 series RTL from Fairchild
SN178xx " " " " "
SN159xx 900/800 series DTL from Fairchild
SN158xx " " " " "
SN154xx custom digital logic circuits
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