You are standing in a clearing in the Great Blue forest. Before you
is a tree representing video-terminal products made by International
Business Machines.
The tree's
first branch emerges low on the trunk--where it almost hangs down
into the mulch of punchcardchad.
This old branch has the cryptic initials EBCDIC carved into it in a style that looks vaguely
like the transit numbers on a check.
The
second branch is not as hoary, and seems to have been grafted onto the
trunk, higher up. The tattered red-white-and-blue remains of an
American flag are tangled into the twigs, near what may have been an
eagle's nest.
At the top of the tree, there is
a new branch,
green and leafy, but with sprouts intertwined in an intricate pattern.
There is an old camp stool here.
Perhaps to your surprise, there are no mice here.
The page you are viewing concentrates on the particular features of IBM
terminals and emulations of them. For information that applies in general
to all video terminals, see the
general information page.
Some vendors of terminal-emulation software for PCs and Macintoshes
have been claiming to "support"
3270 terminal emulation--when what
the product actually supports is mere emulation of a Televideo
terminal with a special keymap that a protocol converter has to interpret.
(The protocol converter also gets to do the tricky work of the
ASCII-to-EBCDIC code translation and
asynchronous/bisynchronous communication bridging.) In some environments, this
setup is what you want, but sometimes you want these functions handled within
the PC--as other products do. Just be certain of what you are getting!
SAS Institute (Emulus 3270 vector-graphics emulator for X Windows)
Some effort was made in the late 1990s to improve the "tn3270" method of
connecting IBM 3270 and 5250 terminals to hosts via TCP/IP. Read about it
here.
There is a use for the camp stool. If your boss has just told you
that you've got to write a 3270 emulator program on a rush schedule,
and you are still puzzled about what "EBCDIC" means, then the stool is
to sit on and take deep breaths for a minute before you go on.
While you're resting, I might as well mention that it stands for
Extended Binary-Coded-Decimal Interchange Code. Have a look at
it.
IBM 3278 Display Console
