Info sought about a pocket terminal

E. Groenenberg quapla at
Sun Apr 26 16:05:49 CDT 2015

> Neat item! If you can't turn up any docs.. here's a thought.
> Since you'd only need one switch to toggle 110 / 300, that potentially
> leaves five for other uses. Not to say they only used one switch for that
> setting, maybe their design required two.. but only one is +required+ at a
> minimum.
> Pretty safe to say that additional switches are used to manually assert /
> de-assert various hardware flow control and device / ring detection lines
> (CTS, DSR, DCD / RLSD) and/or enable / disable hardware flow control. You
> should be able to test for the manual line settings by watching the
> appropriate pins with a meter while trying different switches - see which
> lines are being pulled high / low.
> So how the heck do you operate a one-line terminal, anyway? Does it have a
> scroll-back buffer of 5-10 lines? Do you just have to read way, way fast?
> ;-)
> On Sun, Apr 26, 2015 at 9:06 AM, E. Groenenberg <quapla at> wrote:
>> Sifting through a box of odds 'n ends I came across a sort of pocket
>> terminal. It's casing is of the earlier models TI wedge calculators
>> and has an 8 digit display. Internally there is an intel 8048 processor
>> with some support ttl ic's.
>> A spiral cable with a Db25 connectors goes out from where normally the
>> charger port would have been for the calculators.
>> Behind the battery cover (no space for a battery tough) is a dip switch
>> block with 6 switches.
>> It's made by 'G.R. Electronics LTD' wich had 2 addresses,
>> one in the UK and one in the USA.
>> Google did came with an advert of this device ($395 in 1979) and
>> mentions
>> a selectable speed of 110 - 300 baud and requires a 5V at 450mA.
>> I was wondering if a list member could tell me what the switches are
>> supposed to do (besides setting  the speed)
>> Funny enough, a similar unit was sold recently (item no 220662386232)
>> which
>> has a way higher serial (mine has 7786R)
>> --
>> Dit is een HTML vrije email / This is an HTML free email.
>> Zeg NEE tegen de 'slimme' meter.

Hmm, only 7 wires are connected, and in the connector 2 wires are
joined at one pin, and the blue wire is not used in the db25 connector
housing, so only 5 wires are effectively used.

The wiring :

PockTerm   ----  DB25
1 - pink         pin 3
2 - white        pin 4,20
3 - blue         nc
4 - grey         pin 7
5 - brown        pin 9
6 - green        pin 2
7 - yellow       pin 7

Pin 9 is somewhat unusual, maybe for power?

Regarding the switches, one for 110/300, one (or 2) for parity control
and one for number of stop bits? Left over are 3 or 2 other settings.


Dit is een HTML vrije email / This is an HTML free email.
Zeg NEE tegen de 'slimme' meter.

More information about the cctalk mailing list