🚀 go-pugleaf

NANSI.sys is a shareware replacement for the MS-DOS screen driver ANSI.SYS 
and is completely compatible with the original, so far as I have tested it.  
In addition to the standard escape sequences to clear the screen, underline
words and show them in reverse video, change colors etc. it also has
escape sequences that let you insert and delete lines and characters on
the screen.  Cursor motions are also supported.  Tabs are set by default
every 8 columns but are replaced by spaces on input, so the "insert, delete"
character functions behave as if the text had spaces to begin with -- OK
sometimes but not others.

NANSI.SYS is optimized for multiple-character writes to the screen.  It is
a smidgen faster for single character writes, but nothing short of
spectacular for multiple-character writes.  To get the maximum speed from
it you must set stdin to "raw" mode -- a set of small routines is included
in the package to help you do this -- and then write as many characters to the
screen in one gulp as possible.  I am writing a Reduced Instruction Set text
editor in C which emits escape sequences for NANSI.SYS; I require no other
assembly-language "speed-ups" to make it operate acceptably fast -- screen
updates for the most part appear instantaneous, including those cases where
I must re-write the entire screen.  It blinks quickly, and the new text is
there to read.  I was astonished.

The failure to handle tabs "properly" is the only shortcoming I've noticed ...
and that is really more a matter of taste than anything else.  The popular
shareware editor PC-WRITE also replaces tabs with spaces on input.  For my
application the RISTE must be included as part of another program, and "true"
tab action is needed.  I found I could re-write a whole screen line from
the internal text buffer so fast that single-character operations were
completely unnecessary, and "true" tab operations could be included without
any speed sacrifice.

If you're still using ANSI.SYS you are wasting your time -- literally.

-- 
Ed Nather
Astronomy Dept, U of Texas @ Austin
{allegra,ihnp4}!{noao,ut-sally}!utastro!nather
nather@astro.AS.UTEXAS.EDU