[sdiy] Mac users - excellent keyboard similar to IBM

[René Schmitz]

On 01.06.2021 02:03, cheater cheater wrote:
> I have no idea how that would work - I have one of those modules here
> - or at least very similar, using the same switch technology. I can't
> see any way to lock keys from being pressed like that... any clue how
> that might have worked?


I do remember that there was a click sound, so maybe it was a solenoid. 
So I searched for "3270 keyboard solenoid".

Here is some talk about that:

https://news.ycombinator.com/item?id=19531157


It must have been terminals of the era of 3270/3278. Not the later 
generation that Neils keyboard is related to.


I think I can now piece it together:

You'd normally get the solenoid relaying to you that the key was 
registered, I.e. the click sound you expected was generated

by the solenoid banging against the case for each key stroke. In 
addition to any sound from the key it self.

When the keyboard was in the locked state, it didn't give you that 
feedback. So you had tactile feedback that was different.

Giving you a the impression the keyboard was "jammed", due to the lack 
of sound. But you could still press them after all.

Any mechanics to accomplish this would be overkill for such a purpose. 
(Not that that has never stopped the manufacturers...)


This was mostly a "alert the operator" thing, so it wouldn't really need 
you to prevent pushing down the keys.

In fact you typically had to press one of the PA1/2/3 keys to unfreeze, 
move the cursor, and continue.


So maybe this is interesting for your clicky synth keyboard idea after all:

Put a solenoid in. And if you play out of tune or off the beat, lock the 
keyboard.  :)


Best,

  René


> On Mon, May 31, 2021 at 8:39 PM René Schmitz <synth at schmitzbits.de> wrote:
>>
>> There were many different types of 3270 (and compatible) Terminals.
>>
>> However the operating system must had support for this.
>>
>> A quick search revealed this:
>>
>> http://www.columbia.edu/cu/computinghistory/3270.html
>>
>> "Users are generally presented with forms to fill out. The user moves
>> about the form with arrow, tab, and backtab keys, filling in and
>> correcting the various fields, and then presses the Enter key when ready
>> to submit the form to the mainframe. The mainframe receives a series of
>> data elements tagged to identify which field they belong to. When the
>> mainframe is not ready for input, it literally "locks" the keyboard."
>>
>>
>> Best,
>>
>>    René
>>
>>
>> Am 31.05.2021 um 15:56 schrieb cheater cheater via Synth-diy:
>>> Nope, the IBM 3270 is a beam spring keyboard. I have one here at home.
>>> There is no conceivable locking mechanism. I think Rene is talking
>>> about a Model A or even Model 01 converted to TTY. Those keyboards
>>> used a drive shaft that propelled the keys forward, otherwise they
>>> felt "stuck". If the motor wasn't on, the drive cylinder was not
>>> moving, and the key wouldn't operate... but I don't know if it would
>>> feel "stuck". I don't remember which of the ancient IBM typewriters
>>> had a drive cylinder, but I knew half a year ago.
>>>
>>> On Mon, May 31, 2021 at 10:34 AM Vladimir Pantelic via Synth-diy
>>> <synth-diy at synth-diy.org> wrote:
>>>> On 31.05.21 10:17, René Schmitz wrote:
>>>>> They look similar to the keyboards used on mainframe terminals on an IBM
>>>>> System 370.
>>>> yes, that's the keyboard my Mom had at work, together with an IBM 3270
>>>> terminal. as a kid I was impressed that it had F1 - F12 and PF1 - PF24 :)
>>>>
>>>> And separate RETURN (as in next line) and ENTER (send the form to the
>>>> mainframe) keys.
>>>>
>>>> when she had to use my PC to work from home she asked me where my ENTER
>>>> (send form) key was - eventually we found out it was mapped to F3 for
>>>> measly PC users...
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