[GreenKeys] Model 43 and Altair 8800

[Jeff G]

Welcome to the list! I'm the person from Reddit that pointed you here. The
problem you're having is called "local echo", and I'm not sure if the 43
has a button or setting to turn it off. I looked at mine briefly but didn't
appear to be an option at least on the switches on the keyboard. Meaning,
the machine itself is printing the character while the character is also
coming from the OS, hence why you're getting doubles. You -could- try the
duplex button and see if that helps.

Jeff

On Mon, Sep 30, 2024 at 10:36 AM Paul Wills (CKT&T) <
pdwills at cedarknolltelephone.com> wrote:

> Jon,
>
> It sounds, to me, like it's coming from the computer end.  The computer
> is echoing the character you typed.  I had that problem with my CP/M
> computer years ago and ended up writing a driver that would "eat" the
> next outgoing character if it matched the last incoming character.
>
> Hopefully, you can find an easier way.
>
> PDW
>
> On 9/30/2024 2:10 AM, Del Rey Custom Shop wrote:
> > Hi, new to the list...and wondering if anyone has any ideas about an
> > issue I'm having with a Model 43 KSR with TTL board, hooked up to an
> > S-100 computer, in this case a Vector Graphic, from the laste 70's.
> >
> > I am going through a DB25 null modem, so handshaking is there along
> > with the correct pin assignments, yada yada. The Altair correctly
> > prints out the monitor prompts to the Model 43 and I'm able to issue
> > commands to it from the Teletype, as well as receive back the correct
> > data. The data received back from the computer looks fine and
> > characters aren't doubled.
> > A problem arises when I type in commands from the 43. Characters are
> > repeated, eg, typing 1234 will yield 11223344. I'm not sure what is
> > causing this.
> >
> > An interesting thing is that when I communicate to my PC's terminal
> > program, from the 43, the doubling of characters doesn't occur. On
> > that I have it set to 7 data bits, Even parity, 1 stop bits.
> >
> > Currently, both machines are set to 300 baud. On the 43 I have Parity
> > Off and on Full Duplex. I'm not sure if the problem is on the computer
> > or Teletype side.
> >
> > Thanks for your input,
> > Jon
> >
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