
The troff in this directory
is a troff that produces machine-independent output.
It requires a file of descriptive information about
the particular typesetter you have in mind, and produces
output parameterized for that device.

Thus:
	troff -Taps ...
produces output for the Autologic APS-5.
(This is the default.)

To make this work, one needs to create a set of
device and font descriptions in the directory
	/usr/lib/font/devxxx
where "xxx" is your device name.
Currently supported devices are
	aps	Autologic APS-5

The file "DESC" contains information about the
device itself and the character set.  The file devaps/DESC
is a good example; follow the format closely.

In addition, each font needs a description of its
characters, width and device-driving codes;
see devaps/R and S for typical examples.

The program "makedev" will convert these text
descriptions into a binary form that the troff can
slurp up in a single gulp during initialization;
these wind up in devaps/DESC.out (which includes
default font info) and XX.out for info about font XX.

The second half of the job is to write a post-processor
that converts the more or less machine-independent troff
output into specific codes for your favorite typesetter.
daps.c is the driver for the APS-5;
it will serve as a useful prototype.  In particular,
it contains a precise description of the output language.
Other postprocessors are
	tc	tektronix 4014
	hc	hp2621 (mainly for crude graphics)
	ta	prints ascii on ordinary terminals (crudely)

The aps driver writes onto /dev/aps in the same way that
old troff writes on /dev/cat; to get its output on the std output,
use, e.g., daps -t ... >file.

One can always simply run
	troff
and look at the output; it is guaranteed to be ascii text
and thus safe to edit, grep, etc.
(Since it is ascii, it is also guaranteed to be quite voluminous.)
SCCS @(#)README	1.3
