ref: 49f8ab2aa7b011c005af8faca925ce4cf2c21ef9
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.