From: "Dave Dunfield" <dave04a at dunfield.com> Sent: Friday, April 15, 2005 1:51 PM I've started a webpage on bringing up S100 computers but haven't added much to help here yet. With a totally dead computer start at the beginning: 1) Check the +5v, if you have a scope check for ripple. 2) Look carefully at everything on the PC board, physical evidence of badcomponents: resistors & caps turn brown to black. Plastic IC's turn gray to white. Many components are cracked 3) Check for cold solder joints. 4) Buy a good logic probe, ebay sells them for under $25. 5) If you use a DMM to check logic level remember: If you measure from ground >3v is high, <3v is not low. To measure low measure from +5. If all you measure from is ground you won't know if it is open. Logic can be high, low, or open. An open line may mean the chip driving the line is bad. 6) Start by checking the MPU address lines to see if the addresses are changing, if not it probably is a bad clock or bad 6502. Randy www.s100-manuals.com