1. A method of booting a multiple-processor system comprising the steps of: transferring a message from an external device a first register using a first processor; transferring the message from the first processor to a second processor, said step of transferring comprising the substeps of: setting a flag in a second register with the first processor; detecting the flag with the second processor; reading the message from the first register using the second processor: and clearing the flag with the second processor; checking that the message passed to the second processor without error; interpreting the message with a selected one of the first and second processors; and performing boot operations with the selected processor in response to said step of interpreting the message.