Page 130 - The Unofficial Guide to Lego Mindstorms Robots

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pbFORTH from your RCX, you'll need to remove the batteries to clear the memory. Then you can use nqc or firmdl to
download a different set of firmware. If you want to reinstall the default firmware, you can use the RIS software.

Talking to pbFORTH

To interact with pbFORTH, you need to use a terminal emulator to exchange data with the RCX over the IR link.

W indows users can use the HyperTerminal application that comes with Windows. Linux users can use minicom or
something s imilar. You'll need to point your emulator at whatever serial port has the IR tower attached. The other relevant
se ttings are 2400 Baud, 8 data bits, 1 stop bit, and no parity.

Once you've got your emulator running, press Enter on your keyboard a couple of times. pbFORTH should respond with ''ok"
messages:

ok
o k

To get a q uick start with pbFORTH, let's turn on one of the outputs. First, you'll need to initialize the RCX like this (the stuff
you should type is shown in bold):

RCX_INIT
Ok

To turn on an output, use the MOTOR_SET command, which will be covered later. Type the following:

7 2 0 MOTOR_SET
ok

Re member to press Return after you enter the whole line. Depending on your terminal settings, you will see the letters you
type two or three tim es in a row, like this:

77 22 00 MMOOTTOORR__SSEETT

I have remove d the extra letters in the examples in this chapter, for clarity. To minimize the repeated characters as you type in
th e examples, mak e sure "local echo" is disabled in your terminal emulator.

The MOTOR_SET line turns on output A (represented in the code by 0) in rever se (represented by 2) with full power
(represented by 7). If your R CX is about to drive off your desk, you can turn off the output like this:

7 3 0 MOTOR_SET
ok