Motorola MVME177 manual Status codes that may be set by the bus master are

Multiprocessor Support

The status codes stored in the MPCR are of two types:

❏Status returned (from the monitor)

❏Status set (by the bus master)

The status codes that may be returned from the monitor are:

HEX	0	(HEX 00)	--	Wait. Initialization not yet complete.
ASCII	R	(HEX 52)	--	Ready. The Þrmware monitor is watching for a change.
ASCII	E	(HEX 45)	--	Code pointed to by the MPAR address is executing.

The status codes that may be set by the bus master are:

ASCII	G	(HEX 47)	--	Use Go Direct (GD) logic specifying the MPAR address.
ASCII	B	(HEX 42)	--	Install breakpoints using the Go (G) logic.

The Multiprocessor Address Register (MPAR), located in shared RAM location of $804 offset from the base address the debugger loads it at, contains the second of two longwords used to control communication between processors. The MPAR contents specify the address at which execution for the remote processor is to begin if the MPCR contains a G or B. The MPAR is organized as follows:

$804 * * * * (MPAR)

At power-up, the debug monitor self-test routines initialize RAM, including the memory locations used for multi-processor support ($800 through $807).

The MPCR contains $00 at power-up, indicating that initialization is not yet complete. As the initialization proceeds, the execution path comes to the ÒpromptÓ routine. Before sending the prompt, this routine places an R in the MPCR to indicate that initialization is complete. Then the prompt is sent.

If no terminal is connected to the port, the MPCR is still polled to determine whether an external processor requires control to be passed to the dual-port RAM. If a terminal does respond, the MPCR is polled for the same purpose while the serial port is being polled for user input.

B

B-23