At a charity book sale I turned up this book* which promised to "turn an ordinary electronics technician into a computer maintenance specialist". And what a wide open field it was - as it says in Chapter 1: "as of some recent reckonong, there were in the neighborhood of some 50,000 computers currently in operation in some capacity or other" The book used as an example of a "Typical Small Computer" the Computer Automation PDC 808. The picture of the roughly Altair/Imsai sized box was actually labelled "PDC 808 Controller". The CCC list says this box was released in May 1968 (4K of 8-bit core) and there are just a couple of references to it on the Web I can find, and none from recent years. The book contains over 200 pages covering this device to the minutest detail. It seems a shame that such an apparently rare machine was chosen so we do not have a chance to work through the exercise today - it is rare sin't it? *by Brice Ward, published by Foulsham-Tab Ltd (the English version of the American TAB books) Phil