After our publications covering the 89S8252 Flash Micro Board (December 2001) and the PICee Development System (February 2002) it’s high time to devote some attention to the AT90S2313 microcontroller. As with the other two designs we describe a powerful single-board computer that’s not just excellent for educational purposes but also for general use by microcontroller enthusiasts.The development system described in this article is the spitting image of the PICee board you may have seen in the February 2002 magazine. This is not surprising, for two reasons. Firstly, the AT90S2313 resembles the PIC16F84 in that it has two supply connections, a reset pin, two connections for the oscillator circuit and a number of port pins that allow the micro to be linked to external hardware. Just like its predecessor, the present development system features a number of LEDs for easy visualisation of port pin logic states during software development, a number of pushbuttons, one connector for the link to a standard alphanumerical LC display module and another for external hardware.