The Visicom could - and possibly still can - be used to transfer text over an ordinary telephone line between Visicom users. As soon as one letter is typed it appears on the other user's screen. It works in a kind of a half duplex mode: only one user should type at the same time but both users could type simultaneous. That, however, would result in gibberish. Typing an "X" would tell your communication partner that you are done writing and it's his turn. That's why the X legend is red. The double stepped, red keys on the top of the keyboard are function keys to control the Visicom's interface.
Apparently, there used to be an operator service run by the Dutch national telephone company (PTT, later KPN) that would translate messages between teksttelefoon users and normal, i.e. audio, telephones.
The keyboard's keycaps are double-shot and have an inverse cross mount. The red function keys are pad-printed. There are no stabilizers present except under the space bar.
On the inside, there is a large PCB supporting the switches. It's made by DS Electronics (now Printec-DS). The switches are new to me. They are silicon domes over carbon contacts. These carbon contacts are part of the PCB, and the switch housings with sliders are mechanically locked into the PCB. No soldering is required. In fact, the only soldered contacts are on the connector to the controller daughter board.
I couldn't find these switches on Printec-DS' website but according to a representative, this is the "S7" switch family which is still in production.
The Visicom still seems to work: I've connected it to a monitor and fired it up, and I could navigate the interface. Maybe I should connect it to my telephone line and call someone
- Visicom II with keyboard.
- Goedhart-Visicom-lowres-a.jpg (129.04 KiB) Viewed 2578 times
- keyboard without caps.
- Goedhart-Visicom-lowres-b.jpg (144.27 KiB) Viewed 2578 times
- keycaps.
- Goedhart-Visicom-lowres-c.jpg (130.25 KiB) Viewed 2578 times
- keycaps, bottom side.
- Goedhart-Visicom-lowres-d.jpg (117.42 KiB) Viewed 2578 times
- PCB, bottom side. Note the solderless switch mounting.
- Goedhart-Visicom-lowres-e.jpg (148.45 KiB) Viewed 2578 times
- Dissassembled Printec-DS S7 switch
- Goedhart-Visicom-lowres-f.jpg (111.62 KiB) Viewed 2578 times
- Bottom side of the S7 switch.
- Goedhart-Visicom-lowres-g.jpg (143.86 KiB) Viewed 2578 times
- PCB detail showing the carbon contacts.
- Goedhart-Visicom-lowres-h.jpg (120.31 KiB) Viewed 2578 times
