LEGO MINDSTORMS Robots Manual page 110

Page 118
Figure 6-1.
pbFORTH software architecture
Forth is an interpreted language, which means you can type commands to pbFORTH and have the robot respond immediately. You don't have to compile and download programs; you simply type
them directly to the interpreter.
Installing pbFORTH
Installing pbFORTH is a simple process:
1. Obtain pbFORTH from http://www.hempeldesigngroup.com/lego/pbFORTH/. It's available as an archive that contains the pbFORTH replacement firmware, the source code, and example
scripts.
2. Install pbFORTH on the RCX. To do this, you'll need a firmware downloader. The firmware downloader is a piece of software that knows how to transmit firmware over the IR link to the RCX.
Two freely available firmware downloaders are nqc (described in Chapter 4) and firmdl, available in C source code at http://graphics.stanford.edu/~kekoa/rcx/tools.html. Downloading
firmware to the RCX takes a couple of minutes, so be prepared to wait.
To download pbFORTH using nqc, for example, you use the -firmware option, like this:
nqc -firmware pbforth.srec
When the download is complete, your RCX's screen will go entirely blank. Although the RCX looks dead, don't be fooled. pbFORTH is running, and you will be able to talk to it as described in
the next section.
pbFORTH will remain running on your RCX as long as the batteries are good. It replaces the regular MINDSTORMS firmware entirely, so you won't be able to program with RCX Code or NQC
without reinstalling the regular firmware. To remove