Getting started

Although we will be using FlashForth on a PIC18 microcontroller, we communicate with it using a serial terminal program running on a personal computer. On linux, the gtkterm terminal program is convenient and can be started with the command

 $ sudo gtkterm --port=/dev/ttyUSB0 --speed=38400 --delay=10 --flow=Xon

Pressing the key a couple of times should get the display as shown in Figure1. The ok<$,ram> prompt indicates that the current base for representing numbers in hexadecimal format and that the current context for making variables is static RAM, rather than the Flash memory and EEPROM that is also available in the microcontroller.

Figure 1: Opening screen using gtkterm.

In contrast to Forth on a PC, FlashForth is case sensitive, with most predefined words being spelled with lower case. Also, being intended for use in an embedded system, there is no command to exit the system. FlashForth only stops when the power is removed or a reset occurs.