Lego Mindstorm

Lego Mindstorm can be easily controlled within Squeak. The PECOS model is a component model focused on embedded system. It has been implemented in Squeak.

PECOS The PErvasive COmponent System is a component based model for embedded systems. It consists mainly of components communication throught ports connected with connections. There are three component types:

  • Active Component: Runs in its own thread.
  • Event Component: Runs in an own thread if a certain event has taken place
  • Passive Component: Encapsulates program logic and is called by other components. (Runs in the callers thread)

RCX The RCX is the main brick of the Lego Mindstorms RIS. It’s a Hitachi Microprocessor board with some external ports. These ports are either input (through an A/D converter) or output. There are three of each kind.


First you have to install the SqLego files

Install: File in all the *.st files. First the SqLego then Pecos-System then Pecos-RCX then PECOS-Tests

There is also a Monticello File at:





Lego Mindstorms:


Alexandre Bergel


Thanks to Andreas Hosbach and Roel Wuyts.

Last changed by admin on 21 April 2009