A monitored burn-in test system and a monitored burn-in test method of microcomputers, which are capable of implementing the monitored burn-in test without increasing a load of software and improving the function of a tester unit. A mutable key capability is advantageous in a variety of applications, such as monitoring a set of users and their login status on a plurality of media servers. A user is allowed to designate a stopping point, such as a breakpoint, within the program and a subset of variables from the group of variables to be associated with the designated stopping point. The first section of magnetic circuit being suitable, in a docking mode, for positioning adjacent to a second section of magnetic circuit in a second device to form a completed magnetic circuit used to transfer power between said first and second device. The trellis describes redundancy in the symbol data sequence Y.