Hello world/Line printer: Difference between revisions

Forth systems currently run on everything from bare metal to modern multi-user operating systems and printers are handled differently on each. This demonstration shows a common way that text output is re-directed to printers and/or other devices by vectoring the action of the Forth word EMIT. Emit takes one character off the stack and outputs it to a device. By defining all I/O with the primitive operation EMIT, we can vector the output anywhere we choose, even on hardware with no O/S. Here we show a very basic printer device driver for an embedded system that adds I/O re-direction to the system's Forth language.