ref: 3f5a4e9f7e3c0d1e7c43d2974049e2eb7bc7b5a0
dir: /sys/src/cmd/postscript/postio/README/
Serial communications program for PostScript printers. Runs as a single read/write process (by default). Use the -R2 option or set splitme to TRUE (file postio.c) to get separate read and write processes. Although not the default, we recommend using separate read and write processes. Sends occasional status queries (control Ts) while transmitting files. Use the -q option or set quiet (file postio.c) to TRUE to disable status queries. Datakit connections are supported on System V and Ninth Edition systems. The syntax (for connecting to a Datakit destination) varies. Check the SYSV and V9 versions of setupline() in file ifdef.c. Set DKHOST and DKSTREAMS to TRUE in postio.mk for streams based DKHOST support. When DKSTREAMS is TRUE postio.mk uses "dknetty" as the stream module. Settings like DKSTREAMS=dkty select a different stream module and may be required for full Datakit support on some systems.