Abstract: A central processing unit (2) and a debug module (10) execute concurrent operations without requiring a data processor (3) to operate in a special debug mode. The use of a bus (25) to communicate data, address, and control information between a core (9) and debug module (10) allows debug module (10) to have access the same internal registers and memory locations as central processing unit (2). While debug module (10) and central processing unit (2) both have the ability to access the same internal registers and memory locations, central processing unit (2) may not modify a value stored in a plurality of breakpoint registers (50) when an Inhibit Processor Writes to Debug Registers (IPW) bit in a CSR (FIG. 8) of a plurality of control registers (40) is set. The IPW bit may only be modified by a command provided by an external development system (7).

Abstract: A central processing unit (2) and a debug module (10) execute concurrent operations without requiring a data processor (3) to operate in a special debug mode. The use of a bus (25) to communicate data, address, and control information between a core (9) and debug module (10) allows debug module (10) to have access the same internal registers and memory locations as central processing unit (2). While debug module (10) and central processing unte (2) both have the ability to access the same internal registers and memory locations, central processing unit (2) may not modify a value stored in a plurality of breakpoint registers (50) when an Inhibit Processor Writes to Debug Registers (IPW) bit in a CSR (FIG. 8) of a plurality of control registers (40) is set. The IPW bit may only be modified by a command provided by an external development system (7).

Abstract: A data processor (3) executes a debug operation by minimally intruding on the real time operation of the data processor and without halting the data processor. The data processor implements a control register (40) which stores trigger response value for determining a function executed by the data processor when a breakpoint signal is asserted. The trigger response values indicates whether a central processing unit (2) of the data processor executes a special debug exception processing routine or suspends operation when the breakpoint signal is asserted.

Abstract: The rear end of the truck frame carries a load boosting wheel assembly. The wheels are mounted on a transverse axle which is supported by a forwardly extending wishbone, the front of which has a ball and socket connection to a depending support bracket. The rear portion of the wishbone is guided for vertical movement between the load carrying position and an elevated position. The wheels are actuated to the downward position by air pressure inside the air bag assembly mounted between the wishbone and the frame. The midsection of the air bag assembly is provided with a rigid annulus which is contained to linear motion.