OK, I've got a supply of MAX 604 Chips. Looking at the schematic suggests that I should just add one of these to U22, and that U22 is right next to the Xilinx and the other MAX604 chip - right? However whilst this chip seems to be an option on it's own (here: http://balloonboard.org/hardware/buildoptions.html ) it looks like I also need to add a couple of links (R12 and R36) _or_ the MAX 894 switch for 5V power to make it anywhere other than the 3V regulator - right? Wookey -- Aleph One Ltd, Bottisham, CAMBRIDGE, CB5 9BA, UK Tel +44 (0) 1223 811679 work: http://www.aleph1.co.uk/ play: http://www.chaos.org.uk/~wookey/