Not Morse code, but the Whitechapel MG1 blinks out an error code using long ans short flashes (0 and 1, I can't remember which way round they are) on a frontpanel LED. This would be great if the error codes were correcly described in the technical manual (hint : a 'multi-bit DRAM failure' can simply mean there's not enough RAM installed for the boot ROM you're using. That one let me a merry dance...) HP9000/200 machines have 8 LEDs connected to an output port on the processor bus. Reset turns them all on, they are then turned off one after another if the CPU is running by the self-test code. The diagnostics may the put up an error code if something has failed. And the error code is 'beeped out' (high and low beeps for 0 and 1) through the internal speaker. Apparently if you 'phoned HP service they would sometimes ask you to run the self-test and listen to the beeps over the 'phone so they knew what board had failed. Again, be careful, the error code (and on-screen messages) don't always accurately describe the fault (as I found when restoring a 9836CU...) -tony