"DoN. Nichols" fired this volley in
:

Does the control support hardware flow control? The CTS/RTS
lines to tell when to stop and start? Sometimes that will work when
the
software DC1/DC3 (also known as Xon/Xoff) won't.


According to the maintenance documentation, the R2E4 BOSS9 control
doesn't support hardware flow-control.

And the BOSS9 _may_ have some underlying OS that we'd have been familiar
with in the mid-80s, but the OS isn't exposed to the user. There are no
command-line inputs, merely prompts (and darned few of them).

Ordinarily, one "expects" to load a program that will fit in 12K on the
BOSS9. In that case, no flow-control of any kind is used -- the program
is just buffered. In the direct numeric control mode, it would appear
that DC1/DC3 flow control is the only one available.

However, as Dave's documentation shows, this isn't a "dumb" text-only
protocol with flow control -- there are VRC checks by the control, and
LRC at the end of each block, and STX/ETB headers/footers on each block,
along with the conventional ETX or EOT at the end of the data.

What Dave mentioned was that by entering a filename of "-1" on the
controller, that it would revert to a dumb XON/XOFF protocol without out
all the other overhead -- useful, I guess, if you're dead-sure your link
is solid, and which would save space and communications time when the
programs consisted of lots of very short lines of code.

However, I could not make that work; at least it didn't appear to. Until
I build up a protocol analyser to watch what's being exchanged, I'm not
sure what protocol EZLink is actually using when I enter the bare "-" for
a filename, followed by the two "execute" depressions.

LLoyd