user manual

Debugger General Information
B-22
B
Network Boot Control Module
The ÒcontrolÓ capability of the Network Boot Control Module is
needed to tie together all the necessary modules (capabilities) and
to sequence the booting process. The booting sequence consists of
two phases:
❏ ÒAddress determination and bootfile selectionÓ phase
❏ ÒFile transferÓ phase
The first phase utilizes the RARP/BOOTP capability and the
second phase utilizes the TFTP capability.
Network I/O Error Codes
177Bug returns an error code whenever an attempted network
operation is unsuccessful.
Multiprocessor Support
The MVME177 dual-port RAM feature makes the shared RAM
available to remote processors as well as to the local processor. This
can be done by either of the following two methods. Either method
can be enabled/disabled by the ENV command as its Remote Start
Switch Method.
Multiprocessor Control Register (MPCR) Method
A remote processor can initiate program execution in the local
MVME177 dual-port RAM by issuing a remote GO command
using the Multiprocessor Control Register (MPCR). The MPCR,
located at shared RAM location of $800 offset from the base address
the debugger loads it at, contains one of two longwords used to
control communication between processors. The MPCR contents
are organized as follows:
$800 * N/A N/A N/A (MPCR)