20 Apr
2006
20 Apr
'06
3:09 p.m.
Jay West wrote:
However, I think you're missing the basic concept
here. The IBM coax
terminals do not speak ascii, nor do they speak RS232. Nor are they
character based like ANY and EVERY terminal you've probably delt with
before. The electrical spec isn't similar to RS232 but current
loop... it is a fundamentally different thing. These terminals are
not only block mode, they speak a VERY robust protocol between the
host and the display. It would be quite difficult to make sense out
of the datastream between the terminal and host in a character based
environment.
I know next to nothing about the M3134. It implements enough to
allow you to hook a 3270-speaking terminal to a DECserver 550.
Quite whether that terminal was then intended to talk to a
DEC system or an IBM system is not clear to me. There were
DEC applications that (apparently) could use block-mode
terminals (the VT131 and/or VT132 did block mode didn't they)
but whether the DS550 would translate the 3270-terminal-speak
into something suitable or not, I don't know.
But I think at the very least the physical layer issues must
be solved by this card (otherwise what's the point)?
Antonio
--
Antonio carlini
arcarlini at iee.org