TI Silent 743/745 question.

Chris Elmquist chrise at pobox.com
Wed Mar 23 15:51:41 CDT 2016

On Wednesday (03/23/2016 at 12:57PM -0400), william degnan wrote:
> >
> > The terminal sends ASCII 0x7F when you press RUBOUT.  This is a
> > non-printing
> > character locally but the remote system can send back whatever it likes
> > in response to receiving that 0x7F.
> >
> What happens when you're in 20 mA mode?  That's what it's for, not serial
> comms unless it's mapped specially.  i.e. it's for emulating a teletype.
> right?

Both of my units are 745 with EIA interface, internal acoustic coupler
and no 20mA.  But checking the manual, I don't see any way that you choose
"20mA mode".  It's not a switch or input to the processor that might
change the firmware behavior.  So I don't think what gets sent on 20mA
would be different than what gets sent on EIA when you press RUBOUT...

A lot of systems in that era used RUBOUT like a backspace operator.
If the terminal sent RUBOUT, the host/OS would interpret that as a
delete character operation and then echo back a backspace, maybe an X,
then accept the new input character.


Chris Elmquist

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