INTRO(9) INTRO(9) NAME intro - introduction to jerq-related software DESCRIPTION Section 9 of this manual lists software for running or supporting Teletype 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 indistinguishable in software from a real terminal; in par- ticular, the interface described in ttyld(4) applies to lay- ers, except for the additional editing capabilities dis- cussed 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 teletype. 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 sim- ply emulate other terminals by down-loading a terminal pro- gram (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 software. The objects of jerq graphics are bit- maps. The primitives that operate on layers are aliased to the bitmap primitives, and the data structures are isomor- phic. When running under mux, a programmer need not con- sider layers as graphical objects at all; the operating sys- tem checks the arguments to the graphics primitives and dis- patches the appropriate 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)