#: 17498 S12/OS9/68000 (OSK)
    09-Feb-93  20:20:17
Sb: #Xon/off
Fm: Bob van der Poel 76510,2203
To: All

Can anyone shed some light on xon/off for me when it comes to device
descriptors. I'm confused about just how these things work.

First off, a terminal program will send xon/off itself when its buffers are
full, etc. For example, sterm will send this when doing a disk save. CIS gets
the xoff and stops sending while the disk stuff is done, then after it gets a
xon it resumes. Makes perfect sense...nothing to do with the driver.

Now, I read in my modem manual that it will resond to xon/off senquences too.
This is kind of scary since it might be the result of binary data being sent
down the line. I have no idea what happens next, but I do think I'll make sure
the modem is not set up that way.

Now, I am using /t3 on a mm/1 with type=80. This is supposed to mean that
hardware handshaking is enabled. I have no idea how a hardware handshake works
over a phone line...probably doesn't. So, maybe the modem knows about it and
will stop sending stuff when told to stop. However, what happens with the guy
on the other end of the modem? Does it keep sending anyway?

So, I assume that xon/off are only used by a driver when its buffer is full and
hardware handshaking is not enabled. In which case the values in the desciptor
are meaningless if hardware handshake is available.

Have I got this right?

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