|
Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
|
Thread Tools |
18th Jun 2020, 7:42 pm | #1 |
Tetrode
Join Date: Mar 2015
Location: London, UK.
Posts: 69
|
GR Electronics Pocket Terminal (circa 1977)
I have cleaned and restored this pocket terminal made by G.R Electronics Ltd, of Newport Gwent.
It seems to use 4-20mA current loop serial interface. Before I power it up and perform some basic testing, does anyone have a user manual for this device? Thanks. |
18th Jun 2020, 7:50 pm | #2 |
Heptode
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 661
|
Re: GR Electronics Pocket Terminal (circa 1977)
Looks like an oyster terminal - the ones a know were RS232 - what connector does it have on it?
|
18th Jun 2020, 8:51 pm | #3 | |
Tetrode
Join Date: Mar 2015
Location: London, UK.
Posts: 69
|
Re: GR Electronics Pocket Terminal (circa 1977)
Thanks for replying.
Quote:
This unit has a 7-pin din plug on the end of the trailing lead. It uses opto-isolators for buffering which is why I am assuming it uses a 4-20mA current loop, and so will not be compatible with RS-232 voltage levels. I have already worked out the pin-out. Pocket Term ---- Function 1 - pink RD 2 - white RD-GND 3 - blue n/c 4 - grey GND 5 - brown +5V 6 - green TD 7 - yellow TD-GND A manual would be useful for understanding how to operate it, and if it offers any special functions, etc. |
|
18th Jun 2020, 8:56 pm | #4 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
|
Re: GR Electronics Pocket Terminal (circa 1977)
They're on Graces Guide;
PS GR Electronics were indeed the original maker of Oyster terminals
__________________
Kevin Last edited by McMurdo; 18th Jun 2020 at 9:00 pm. Reason: added the oyster bit |
18th Jun 2020, 9:07 pm | #5 |
Tetrode
Join Date: Mar 2015
Location: London, UK.
Posts: 69
|
Re: GR Electronics Pocket Terminal (circa 1977)
|
18th Jun 2020, 9:16 pm | #6 |
Guest
Posts: n/a
|
Re: GR Electronics Pocket Terminal (circa 1977)
Looks vary much like a TI58 calculator to me.
|
18th Jun 2020, 9:18 pm | #7 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
|
Re: GR Electronics Pocket Terminal (circa 1977)
I'm not sure. Oyster have been through several changes of ownership through the years like many computer companies. The last time I tried to order parts (back end of last year) I found they had gone out of business again a few weeks earlier. Here's an old magazine advert for yours;
__________________
Kevin |
18th Jun 2020, 9:23 pm | #8 |
Tetrode
Join Date: Mar 2015
Location: London, UK.
Posts: 69
|
Re: GR Electronics Pocket Terminal (circa 1977)
|
18th Jun 2020, 9:26 pm | #9 | |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
|
Re: GR Electronics Pocket Terminal (circa 1977)
Quote:
GR Electronics originally made a portable terminal that opened up like a clamshell, I think this is where the name Oyster came from. http://www.computinghistory.org.uk/d...-165-computer/
__________________
Kevin |
|
21st Jun 2020, 11:09 pm | #10 |
Tetrode
Join Date: Mar 2015
Location: London, UK.
Posts: 69
|
Re: GR Electronics Pocket Terminal (circa 1977)
I worked it all out in the end without any manual.
The Pocket Terminal is now restored and repaired having had to change the 4N25 opto-isolator. It is shown here connected in "loopback" so I am able to echo entered characters to the display. |