term% cat index.txt INTRO(9) Kernel Developer's Manual INTRO(9)
NAME
intro - introduction to jerq-related software
DESCRIPTION
Section 9 of this manual lists software for running or supporting Tele‐
type DMD-5620 terminals, the current implementation of the `jerq'
graphics terminals. Subsections 9.1-9.7 mirror the purposes of the
preceding sections 1-7, with 9.1 being commands, 9.6 being games, etc.
The only `real' 5620 commands are 32ld, which loads programs into the
terminal, and mux, which starts the characteristic `layer' or window
system. The other commands in section 9 either run on Unix or within
mux layers.
A layer is technically a virtual terminal, but is almost indistinguish‐
able in software from a real terminal; in particular, the interface de‐
scribed in ttyld(4) applies to layers, except for the additional edit‐
ing capabilities discussed in mux(9.1).
The commands in sections 9.1 and 9.6 run on Unix, but most also call
32ld to `down-load' a program that replaces the default terminal
process running in the layer, that is, the command's controlling tele‐
type. To Unix the interface is still that of a terminal; in particular
/dev/tty is always connected to the layer. The default mux terminal
program implements the teletype function itself, but when a program is
down-loaded a teletype line discipline is pushed on the stream (see
stream(4) and ttyld(4)). Some commands may simply emulate other termi‐
nals by down-loading a terminal program (see term(9.1); others, such as
the text editor jim(9.1), are really two programs — one on Unix and one
in the layer — communicating using standard input/output on Unix and
sendchar/rcvchar in the terminal; see request(9.2).
There is an identity between bitmaps and layers in the graphics soft‐
ware. The objects of jerq graphics are bitmaps. The primitives that
operate on layers are aliased to the bitmap primitives, and the data
structures are isomorphic. When running under mux, a programmer need
not consider layers as graphical objects at all; the operating system
checks the arguments to the graphics primitives and dispatches the ap‐
propriate operator depending on the type of the argument. Except in
stand-alone software, layers are an invisible implementation detail.
SEE ALSO
32ld(9.1), mux(9.1), stream(4), pt(4)
INTRO(9)