Technical information
1.2 Firmware Overview
Two electrically programmable read-only memory (EPROM) chips on
the
KA670
CPU
module contain
the
firmware. This firmware consists
of
the
following
three
major
programs, which perform
the
system power-on self-
tests
and
diagnostics:
• A console
program
• A
set
of
self-tests for
the
CPU
and
memory
• A
primary
bootstrap
program
(VMB)
The
console
program
receives control
whenever
the
processor
halts.
In
a processor
halt,
processor control
passes
to
the
console
program
and
instruction
execution continues.
The
standard
VAX
console functionality
is
emulated
whenever
you execute a
program
in
ROM.
Control
passes
to
the
firmware
under
any
of
the
following conditions:
• You power-on
the
system.
• You
press
the
Restart
button.
• You
assert
the
Q22-bus BHALT signal
by
pressing
the
Halt
button.
• You
enter
a
break
when
the
Break
EnablelDisable switch
is
set
to
enable.
• A HALT
instruction
is
executed.
• A
system
error
occurs.
Base System Description
1-3