Re: Terminal Graphics Proposal

From: Tony Harminc (
Date: Fri Oct 02 1998 - 19:29:05 EDT

On 30 Sep 98, at 18:35, Frank da Cruz wrote:

> Table 8.1: Miscellaneous Single-Cell Terminal Glyphs
> Code Description Reference
> E0F0 Reverse Question Mark DEC VTxxx, Wyse, Televideo (1)
> E0F1 Box with X inside DG Math 06/07, GCGID SP500000
> E0F2 Human stick figure with hat SNI Facet 04/14
> E0F3 Clock (with hands at 3:00) SNI Klammern 05/01
> E0F4 Overscore asterisk IBM 3270
> E0F5 Overscore semicolon IBM 3270
> E0F6 Padlock (keyboard locked) IBM 3270

This last one introduces a bit of a problem, I think. It differs
from all other characters mentioned in that it is never displayed in
the data portion of a 3270 screen, but rather occurs "below the line"
as an indication of keyboard status. If it is to be included, then
there are several more uniquely 3270 characters that can be seen
below the line; I don't know formal names for them, and indeed they
generally don't appear in IBM's CDRA documents. Roughly, they are:

Outline up arrow (indication of upshifted condition)
Outline down arrow (indication of downshifted (override) condition)
Key (indication of terminal physically locked (I think
                    this may be what is meant by E0F6 above)
Stick figure (terminal is connected to "operator" (really to a
                    supervisory program))
Solid block (terminal is connected to "application program")
4 in square box (terminal is connected to 3274-type control unit)
6 in square box (terminal is connected to 3276-type control unit)
Lightning bolt (communication failure)
Rectangle with slash (machine check)
Printer symbol with slash (associated printer has an error condition)

and most problematic:

Left half of clock (these two form a doublewidth clock (set at 6:10
Right half of clock or 2:30, though I'm sure the time would be
                    considered a matter of glyph - indeed at least
                    one non-IBM manufacturer's clock symbol was 5:50
                    or 10:30)

Now it's entirely reasonable to argue that all the above (and I may
have forgotten a couple) have no business being encoded at all.
Indeed some terminal emulators use graphical means to produce the
symbols. In any case there is nothing in the 3270 architecture that
specifies use of any of them, and an emulator program can use other
means to communicate the same information to the user. However a
number of Windows-based emulators I know do use glyphs encoded in a
font that they supply to produce at least a subset of the symbols.
(It should be pointed out that a number of "ordinary" glyphs can also
appear below the line, but I can think of no reason not to unify them
with the upper case letters, numbers, and so on.)

That IBM doesn't include them in CDRA may be a good reason to exclude
them from this proposal. But they can be genuinely useful for
writers of emulators. What to do ? And how many clocks and stick
figures is it reasonable to encode ?

Tony Harminc

This archive was generated by hypermail 2.1.2 : Tue Jul 10 2001 - 17:20:42 EDT