.TH CAT 4 
.UC
.SH NAME
cat \- phototypesetter interface
.SH DESCRIPTION
.I Cat
provides the interface to a Graphic Systems C/A/T
phototypesetter.
Bytes written on the file specify font, size, and other control
information as well as the characters to be flashed.
The coding will not be described here.
.PP
Only one process may have
this file open at a time.
It is write-only.
.SH FILES
/dev/cat
.SH "SEE ALSO"
troff(1)
.br
Phototypesetter interface specification
.SH DIAGNOSTICS
.I Errno
is set to ENXIO if an
.IR open (2)
fails because the device is already in use.