Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucsd!sdcsvax!ucsdhub!hp-sdd!hplabs!hpfcdc!hpldola!hp-lsd!oldcolo!dave
From: dave@oldcolo.UUCP (Dave Hughes)
Newsgroups: comp.graphics
Subject: Some Basic Naplps Facts
Keywords: naplps
Message-ID: <137@oldcolo.UUCP>
Date: 9 Mar 89 06:27:07 GMT
Organization: Old Colorado City Communications, Colorado Springs, CO
Lines: 78


     In a response to an Amiga graphics-gurus complaint about the 
treatment  by Byte of Amiga's (since muted),  I suggested that if 
Amiga programmers would just develop an encoder (drawing program) 
and  decoder  (terminal  and display program)  using  the  NAPLPS 
standard,  they wouldn't have to worry about Byte - or any  other 
magazine  - being the only showcase for their computer art.  That 
they  could  display it online and bypass print  publications  as 
the only practical distribution media.
     I have since had a number of e-mail questions about NAPLPS - 
what  it is it and where can one find more information about  the 
standard.  I will here oblige in open postings,  for a number  of 
reasons.  I  joined  this newsgroup to find out if there is  more 
expertise out there in NewsNet land on the NAPLPS  standard.  And 
whether  there  is or not,  to see if there were a  few  graphics 
hackers  out  there  interested in helping  develop  some  public 
domain stuff - particularly low end encoder/decoders based on it. 
Or  those who could simply make useful comments and approaches to 
the  aim  of  gaining  more acceptance  for  the  standard  among 
telecommunicators.
     For after 6 years of acquaintance with NAPLPS,  and watching 
others compete in the marketplace, I am convinced it still is:
     (1)the most universal standard for the encoding and  display 
of  animated  graphics  and text for the widest range  of  target 
machines - from the lowest end AppleIIs,  through Amigas, Ataris, 
IBM PCs and MacIntoshes to CAD/CAM.
     (2)is, because of its quite compressed code nature, the most 
suited to generalized telecommunicated graphics.
     And  some  recent  decisions by some  pretty  big  companies 
(IBM/Sears,  Bell Canada) tells me that no other standard yet  is 
as  useful  when  it gets down to the mass  market,  the  general 
business market, and general educational purposes.
     So, for those who don't know what it is, let me start there.
     NAPLPS  stands  for the North  American  Presentation  Level 
Protocol  Syntax.  A  joint ANSI Standard (X3.110-1983)  and  the 
Canadian  Standards  Association  (T500-1983).  One can  get  the 
complete  158 page standard from  ANSI,  1430  Broadway,  NY,  NY 
10018. It cost about $25 a few years ago. Last telephone number I 
had was 212-354-3300.
     The standard was most comprehensively described in a  series 
of 4 Byte articles Feb thru May,  1983 by Jim Fleming and William 
Frezza.
     And  there was another very useful article - together with a 
Tutorial program in C for the key subroutines in NAPLPS, by David 
McCune in the July and August Microsystems Journal.
     NAPLPS  is  a standard for encoding visual information in  a 
compact form.
     Its chief characteristics are:
     (1)  it deals with the 6th or  'Presentation Level' of the 7 
level ISO model.
     (2)  it  uses  primitives  - line,   arc,   point,  polygon, 
rectangle, as well as colors, textures, blink.
     (3) It is compact because it is not a bit map which  travels 
over the phone line,  but a set of instructions for the 'decoder' 
program  in  the target machine to draw the graphics and  textual 
routines within the limits (resolution,  colors) of that machine. 
Thus a Naplps 'frame' can range from a few hundred bytes to  tens 
of  K,  but  with 1-5K being fully adequate for lots of  complete 
displays.  And  a  graphic  drawn on a  Sun  Workstation  can  be 
displayed on an Apple IIc, and visa versa.
     (4)  it  is 'terminal independent' using ratios rather  than 
absolute locations.
     (5)  It is extensible,  since it uses a series  of  'tables' 
which  are invoked.  The standard default tables are  ASCII,  PDI 
(Picture  Definition Instructions),  SUP TXT,  MACRO,  MOSAIC and 
DRCS (Dynamically Redefinable Character Set).  Other tables could 
be  added  - such  as  sound.
     (6)  By  supporting  Macros,  it can  further  decrease  the 
demands  on  telecommunications,  by  storing  ,  temporarily  or 
permanently,  macros  representing graphics subroutines which can 
be called to the screen by even fewer transmitted bytes.
     It also has been a bust in the Videotext marketplace.  For a 
perfectly  understandable set of reasons which have little to  do 
with the standard itself.
     Which I will comment on in the next article.