[Info-vax] escape sequences, cursor positioning

[Richard B. Gilbert]

acid.friend at yahoo.de wrote:
> hi everybody,
> it might be interesting for you to read my previous topic:
> http://groups.google.com/group/comp.os.vms/browse_thread/thread/37b3e5cca7467772#
> 
> in the meantime i managed to get a copy of vt100 user guide and i've
> read the programmers part very carefully, because i want to code
> something in DCL using ASCII escape sequences.
> i've found out that some escape seqences work very well and other
> don't work and now i'm trying to find some help here.
> 
> $ ty specfont.com
> $!------------------------------------------------------------------------------
> $!                                                   PLAYING WITH ESC
> SEQUENCES
> $!------------------------------------------------------------------------------
> $!
> $ esc[0,7] = 27
> $ say = "write sys$output"
> $ say esc+ "(0"
> $ say " ssssssssss"
> $ say esc+ "(A"
> $ say esc+ "[3A"
> $ read sys$command input1/prompt=" "
> 
> this works fine ^^
> 
> but when i modify the "$ say " ssssssssss" line and add a additional
> escape seqence, it won't work.
> 
> $ ty specfontv2.com
> $!------------------------------------------------------------------------------
> $!                                                   PLAYING WITH ESC
> SEQUENCES
> $!------------------------------------------------------------------------------
> $!
> $ esc[0,7] = 27
> $ say = "write sys$output"
> $ say esc+ "(0"
> $!
> $! modified line below, added some spaces in front of the first s
> $ say "   ssssssssss"
> $!
> $ say esc+ "(A"
> $ say esc+ "[3A"
> $!
> $! additional escape sequence below, want the cursor so move right
> (this won't work)
> $ say esc+ "[2C"
> $!
> $ read sys$command input1/prompt=" "
> 
> okay, that's my first problem.
> 
> besides i don't want the underscores/special characters to get
> overwritten when i start typing.
> is there any easy solution for this?
> 

If you have underscores, or ANY other printing character in any given 
character cell, you cannot have another occupying the same cell!!!!

Some video terminals; e.g. VT100 series, VT200 series, etc, will display 
underscored characters but these are NOT a character PLUS an
underscore.  Just think of an underscored character as a whole NEW 
character or a new font.

I don't believe it's possible and even if it can be done, I doubt if the 
result could possibly be worth the effort required.