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From: wd8mln@worldnet.att.net
Subject: Re: Ye Olde Ascii Art FAQ ( Bob Allison )
Date: 1997/09/04
Message-ID: <5unrq4$6f8@bgtnsc02.worldnet.att.net>#1/1
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References: <5umu5n$4qi$4@mnementh.southern.co.nz>
Organization: AT&T WorldNet Services
Newsgroups: alt.ascii-art,alt.ascii-art.animation,alt.binaries.pictures.ascii


>>> Colin Douthwaite posted the "ASCII ART FAQ" and the "Ye Olde Ascii Art FAQ"

Another method that has been used over the years by ham radio operators
sending "RTTY Art" (Radioteletype Art) is the overprint.  This is
especially
useful for the anti-aliased and grey-scale techniques.  The old Teletype
(registered trademark of Teletype Corp.) machines used a 5-bit code,
with
a "remembered" upshift and downshift characters, to give the following
character set:

Capital letters:  A-Z
Numbers:          0-9
Punctuation:      -'$&#()"/:;?,.

The numbers and punctuation were "shifts" of the letters.  The control
codes
were  FIGS (upshift), LTRS (downshift), SPACEBAR, RETURN, LINE FEED and
BLANK
(equivalent to ASCII "NUL").

Anyway, a huge amount of "BAUDOT ART" (RTTY Art) was sent by hams
worldwide
on the 80, 40, 20, 15 and 10 meter bands.  I knew a ham who had a closet
with
several shelves stacked with pie pans, each pan containing a partial
roll of
5-level paper tape with a piece of RTTY Art.

This artwork used the standard Teletype 72-column paper, and since the
RETURN
and LINEFEED were separate characters, much of the best artwork used an
overstrike technique.  One line of characters was sent, then a RETURN,
then
the overprint line, then a RETURN / LINEFEED.  Also, the paper was in
continuous
rolls, so the artwork got rather long.  In those days, hams were limited
to
60 wpm (45.45 baud) BAUDOT or 100 wpm (110 baud) ASCII, the ASCII being
a
"later" development.  So for a 72-column piece of art, overstruck, about
a
foot long, it could take a half hour to an hour to send, and over a
noisy 
radio channel.  Also, we had to pause every 10 minutes to send the
station
ID in morse code.  Phew!

The overprint allowed grayscale to go from a blank overprinted with a
blank
(white) to a W with an M (black) -- these were the extremes with the
typeface
that Teletype Corp. used in their printwheels.  You can imagine the 
possibilities for anti-aliased grey-scale art by picking characters that
give the shading in the correct portion of the character cell!
(like   /  with  ,  -vs-   /  with  '  for example)

Anyway, I hope to find a few pieces of art to post (which are NOT
overstruck).
I also hope to find a way to convert the paper tapes to ASCII disk files
and to take the overstruck lines and put them on two separate pieces of
paper, which can then be run through a copier onto a single sheet, or
held up to the light, or whatever, so that the overprinted lines line
up.

Hope this bit of history helps, and I hope to have some items to post
in the not-too-distant future.

73
DE  Dale WD8MLN

wd8mln@worldnet.att.net

W       W  DDDDD     88888   M       M  L        N     N
W   W   W  D    D   8     8  MM     MM  L        NN    N
W   W   W  D     D  8     8  M M   M M  L        N N   N
W   W   W  D     D   88888   M  M M  M  L        N  N  N
W   W   W  D     D  8     8  M   M   M  L        N   N N
 W W W W   D    D   8     8  M       M  L        N    NN
  W   W    DDDDD     88888   M       M  LLLLLLL  N     N

//////////////////////////////////////////////////////////

(Amateurish, I know, but effective.)