[GreenKeys] Keyboards - 32/33 and Compact 28 KSR

[Nick England]

Ummm, it was 1964 and they weren’t making M15 keyboards any more. This
32/33/28compact keyboard was in production and is light, small, requires no
motor, and is easy to interface. Weren’t no UART chips back then.

Yes a key press released code bars which activated wire switches including
one which signaled “data ready”. The release pulse (ack) drove a solenoid
to reset the code bars.
The 28 compact keyboard used the same 115vac solenoid. So does the
prototype 28 compact KTR I have.

The 32/33 used a mechanical linkage from the distributor to reset the
keyboard (as did the photoelectric 28 compact AN/UGC-77).

The manual with descriptions is here
https://www.navy-radio.com/manuals/tty/289B-6409.pdf

Cheers,
Nick




On Sat, Mar 18, 2023 at 4:00 PM Harold Hallikainen via GreenKeys <
greenkeys at mailman.qth.net> wrote:

> As I recall from reading the datasheet on that keyboard, it had an
> interesting interface.
>
> It appears the keyboard was all mechanical. I suspect there were code bars
> under the keys, like in the model 15, that opened or closed switches for
> each bit. Once a key was pressed, it, or at least the code bars, were
> locked in place and another switch closed indicating the character was
> ready. The computer detected the "character ready" signal, captured the
> character from the code switches, then sent a pulse to release the lock on
> the key so the next key could be pressed. I suspect this pulse also
> released the character ready switch so the computer would not repeatedly
> capture the same key.
>
> As I recall from reading the datasheet, the interface was parallel, as
> described above. It's interesting that they did not just stick a motor on
> a model 15 keyboard and use a serial interface.
>
> Harold
>
>
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-- 
Nick England K4NYW
www.navy-radio.com
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