Specifications

APPENDIX C
IMPLEMENTATION SPECIFIC DUMPILOAD CHARACTERISTICS
This appendix documents characteristics of PDP-11 dump/load programs
existing as of the date of this specification.
C.1 Secondary Loader
The secondary loader is sent as
a single Memory Load with Transfer
Address message as normally required. In addition to this
requirementI
it must be loaded and started at location 6. Current
secondary loaders are between 400 and
600 bytes in lengthI depending
upon the device type used. They use the stack address set up by the
primary loader. For current loaders this will be between
17400(octal)
and 17776(0ctal). The secondary loader assigns its buffer space below
the stack. The secondary loader accept: Memory Load with and without
Transfer Address messages.
It isI therefore, capable of doing
multi-block loads into absolute addresses without memory management.
It requests a tertiary loader to be loaded.
The DMP-11
and DMV-11 do not set
up the
stack pointer or
Rl as
described.
For those
devicesI
Rl contains
the device unit number.
C.2 Tertiary Loader
The tertiary loader is loaded by the secondary in a multi-block load
starting at location lOOOO~octal~. It will run with memory management
on
if it exists on the system. The tertiary loader moves itself to
the top of physical memory and assigns its stack and buffer space just
below itself. It
isI therefore, capable of multi-block loads from
location 0
up to its buffer address, usually the last 1-2K words of
physical memory. It requests the operating system to be loaded. The
current tertiary loaders do not specify any specific operating system.
The choice of system to send is established by prior agreement or by
command at the host system.