The Adaptec ACB-2070a controller has built-in self diagnostics. These arre performed at power on when the K-L jumper is installed. Do NOT connect the cables. If the board is functioning properly, the LED will flash continuously with a duration of 0.5 - 1.0 seconds per flash. If there is a problem with the controller, the LED will stay on for six seconds, flash once for one second (notating the start of diagnostics), and then flash in 0.5-second bursts. This will then be repeated as long as the K-L jumper is installed. The number of 0.5 second bursts is the error code. <> <> None 8085 Subsystem 1 8156 RAM 2 2764 Firmware eprom 3 AIC-010 and related logic 4 AIC-010 and related logic 5 AIC-300 and related logic 6 2114 RAM chip Continuous bursts of 1 second, 1 second and 1/2 second (without 6 second flash and 1 second flash) indicate that the controller passes self diagnostics.