I have determined that the problem with my TRS-80 Model IV is a bad disk controller chip... Unfortunately I don't have a spare - does anyone here have an extra Western Digital 1793 (or compatible) FDC chip? I have no trouble sucking it off of a board if necessary. Am located near Ottawa, Ontario Canada, but will pay shipping costs Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Vintage computing equipment collector. http://www.parse.com/~ddunfield/museum/index.html