v7 man page for cat

CAT(4)							     Kernel Interfaces Manual							    CAT(4)

NAME
       cat - phototypesetter interface

DESCRIPTION
       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.

       Only one process may have this file open at a time.  It is write-only.

FILES
       /dev/cat

SEE ALSO
       troff(1)
       Phototypesetter interface specification

																	    CAT(4)