Re: Basic comms question

[dempson@actrix.gen.nz (David Empson)]

Jim <jim@magrathea.plus.com> wrote:

> Ok, numpty question time:
> 
> If I switch on my //e, <ctrl>Reset it to get a prompt, then type PR#2,
> does that mean that all keyboard input is redirected to slot 2 (serial
> card in this case)?

Not exactly. It means all screen output is redirected to slot 2.

"PR#" means "PRint to slot number ...".

Assuming you haven't also redirected input from the keyboard and
something is actually waiting for keypresses and echoing them (e.g.
you're still at the command prompt), then yes - anything you type should
be sent out the serial port (along with any command prompts and other
text displayed by the computer).

You could run into problems with character interpretation. The Apple II
uses CR by itself to mean "go to start of next line" whereas most ASCII
terminals (or software emulating one) expects CR to mean "go to start of
current line" and there should be a subsequent LF to advance to the next
line.

With a SSC, this is normally handled by the serial firmware
automatically adding LF characters if it is configured to do so. I don't
know how your CCS 7710 will behave but it should do this by default if
it is intended to be used with a serial printer.

> In which case, assuming there's a device on the other end (null modem
> cable) with matching comms parameters, anything I type on the //e should
> show up?
> 
> Similarly, IN#2 and typing on the remote device should show on the //e
> screen?

Same rule. Keyboard input is redirected from slot 2.

"IN#" means "INput from slot number ...".

Assuming you haven't also redirected output from the screen and
something is actually waiting for keypresses and echoing them (e.g.
you're still at the command prompt), then yes - anything you type on the
remote device should appear on the Apple //e screen.

If both commands are active at the same time (PR#2 and IN#2) while at
the command prompt, anything typed on the remote device will be echoed
back to the remote device (along with all prompts and other text
displayed by the computer).

To return either function to normal, use PR#0 or IN#0 respectively.
-- 
David Empson
dempson@actrix.gen.nz