TWIN Terminal

The terminal is a rebranded version of the Mini-Bee terminal by Beehive Medical Systems. The same terminal was also sold as the Hewlett Packard 2615A.

  • 12″ display, 80 chars x 25 lines, 60 Hz refresh
  • 53 key detachable keyboard
  • Interface RS-232B, 110 to 9600 baud switch selectable, full/half duplex switch selectable, parity and stop bits configurable.
  • Weight main display 20.5 kg, keyboard 3.6 kg
Signetics TWIN terminal, in storage.

Fortunately the terminal is rated for 230V mains. After some initial checks I plugged in the mains. The first problem immediately became apparent, as the on/off switch was stuck in the on position. Furthermore, some of the voltages from the power supply were missing. Also, the toggle switch for selecting the baud rate was broken off.

To repair the power supply it was sufficient to replace most of the capacitors. Replacing the two switches at the back was also not complicated. Exactly the same toggle switches can still be bought from local electronics parts shops. The terminal is now working. The image is sharp and just a little bit jittery.


Some initial pictures of the monitor.


I took some pictures while cleaning the keyboard. The keycaps were grimy, but otherwise the inside was remarkably clean. After some soap and rubbing the keys are shiny again.

The nine ICs inside the keyboard are:

  • IC1: MC836P, datecode 7442, hex inverter.
  • IC2: 946 PC, datecode 7418, quad input NAND gate?
  • IC3: SW 18122p, datecode 7346, ???
  • IC4: SW 18122P, datecode 7346, ???
  • IC5: RCA CA3046, array 0f 5 NPN transistors.
  • IC6: M RW-10039, datecode 7341, 7-to-4 binary encoder
  • IC7: M RW10039, datecode 7341, 7-to-4 binary encoder
  • IC8: M RW-10038, datecode 7329, 8-to-4 binary encoder
  • IC9: M RW-10038, datecode 7329, 8-to-4 binary encoder

See the Mini-Bee Service Manual in the column on the right for details.

Manuals on this terminal: contains an incredible amount of information on Micro Switch keyboards and switches.