Diagnostic Wrap Mode for System Interface
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
The diagnostic wrap mode for system interface provides the processor with the ability to analyze a system bus interface and logic lines feeding it, without using a second bus unit. The wrap mode is a method of sending data, present at the input, of the system bus drivers back to the communication register, to allow the bus subunit to test itself, up to the point that the data goes on to the bus without actually putting the data on the bus. The four bytes directly on the system bus 12 make this wrapping possible. By adding some logic to the set condition, the communication register 13 can be used to latch both the external data bus 14 and the address bus 15 that feed the system bus multiplexer 16.