The so-called magic black box is a collection of analog circuitry and the Atmel AT90S8515 chip on a STK200 board with external RAM. The circuitry on the incoming signal from the guitar does a level-shift so that singal is centered around 2.5 V, an amplification, and filtering which is to prepare the signal for analog-to-digital conversion. The A-to-D is done inside a Maxim 1110 8-bit ADC chip. The circuitry on the output consists of a 7-bit digital-to-analog converter, and some filters and a voltage divider (to bring the signal back down to original levels).