4 ms·
Some of IBM's mainframe terminals used a solenoid which would hit the side of the keyboard's case to indicate that a key-press was successfuly registered. This
by ch_123 8y ago
Some of IBM's mainframe terminals used a solenoid which would hit the side of the keyboard's case to indicate that a key-press was successfuly registered. This was in addition to the well documented clicking noise of IBM's keyboard switches.
- dfox 8y agoIIRC original 3270 keyboard had solenoid that physically prevented user from pressing any key when the terminal was busy and would not be able to register the key press.
- ch_123 8y agoThe solenoid on the one which I have (a 3278 keyboard) is separate to the keys. It is true that the solenoid will not operate when the terminal is unable to accept any key press, but it does not impede the operation of the keys themselves. To the best of my knowledge, the only IBM keyboards that could flat out prevent the keys from being pressed were ones based on the Selectric typewriter mechanism, such as the 2741
- kps 8y agoIn order to prevent two keys being active simultaneously, the Selectric had a linear track full of steel balls running from side to side, with just enough free space to allow a metal tab from a single key to enter. So locking the keyboard was just a matter of having a solenoid occupy the free space.