[Simh] HP Terminal emulators, MSKermit with DosBox, CKermit 9 to the HP3000

[Clem Cole]

On Tue, Apr 12, 2016 at 11:14 PM, Tom Morris <tfmorris at gmail.com> wrote:

> On Wed, Apr 13, 2016 at 12:28 AM, Clem Cole <clemc at ccc.com> wrote:
>
>>
>> ​Hang on -- BREAK is not in the old USASCII ​7 bit map.   As explained in
>> RFC 854, it was a >>key<< on the old Teletype ASR33 (and the ATTEN key on
>> the IBM 2741).   What BREAK did was sent a very long (i.e. 1 second if I
>> remember correctly) "marking" time signal.
>>
> ​Bad wording -- sorry see below...​



>
>>
>

> Definitely not an ASCII character,
>
​That was my point.... I'm glad you agree.​




> but where would an ancient electromechanical device like the ASR-33 have
> kept this fancy 1 second timing logic?
>
​That's non-sense.   Timing on electromechanical devices was gears, cams et
al.   The teletypes had plenty of them.​   How BREAK was implemented on the
terminal is not relevant to the conversation, but >>what<< is being sent
its and how to do same function with todays tools.



>
> I'm pretty sure that the length of the break is whatever length you could
> be bothered to hold the key (and thus the line) down.
>
​I dp believe​ you are correct on this.  I'd have to go find the old
documents, but BREAK was defined in one of the communications standards.
IIRC correctly it is as N character times of marking time.   Where N was
defined as a large number - in order of seconds not small sub-seconds.

Again if I recall correctly, BREAK is an concept that came from the morse
code world and was  inherited as transmission standards changed over the
next 100 yrs.




> It was only in much later models of terminals that logic got introduced
> between the BREAK key and the line.
>
I'll take you word on it and I do believe you are correct, I've forgotten
and no longer have access to service manuals in my own archives.​

But it goes back to my point about what was being generated then, how to
generate it today.
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