[Info-vax] Tertiary VMB?

[gerry77 at no.spam.mail.com]

Hello everyone,

the V5.2 version of the "VAX/VMS Internals and Data Structures" (EY-C171E-DP)
book states the following about cluster members booting over the Ethernet:

"NISCS_LOAD can be thought of as a VMB extension. It contains a minimal class
driver and several Ethernet datalink drivers. Using the class driver and the
appropriate datalink driver, the satellite can access the secondary bootstrap
file, normally SYSBOOT, on the system disk served by the host. The minimal
class driver and Ethernet datalink driver present a standard disk interface,
allowing SYSBOOT and the rest of the boot procedure to execute as though
performing a normal disk boot." (§ 30.3.4.1)

"The secondary bootstrap program, SYSBOOT, executes when VMB is directed to
load a VMS system. VMB, having already tested main memory, reads SYSBOOT into
memory and transfers control. (When booting over the Ethernet, VMB loads
NISCS_LOAD and NISCS_LOAD loads SYSBOOT.)" (§ 30.4)

About the same topic, Digital Technical Journal has the following:

"SYSBOOT program could not be loaded directly by a MOP exchange. SYSBOOT
expects to be able to access the boot device as a block-structured storage
device; it does not understand the various types of Ethernet adapters that may
be present. Moreover, SYSBOOT would not have enough information to locate the
system disk. Therefore, another image called NISCS_LOAD is inserted into the
boot sequence between VMB and SYSBOOT. NISCS_LOAD provides the environment
that SYSBOOT needs to do its job correctly." (Vol. 1, n. 7, Sept. 1987)

However, while reading various cluster manuals, I've found many references to
TERTIARY_VMB.EXE, a file which is not mentioned in the above paragraphs. So,
I'm trying to understand where in the process it stands, which are its
functions and possibly when it was introduced. I think It should be something
used before SYSBOOT receives control. Maybe it is loaded by NISCS_LOAD before
SYSBOOT. Does anyone here have some details about that?

Many thanks,
G.


P.S.: I'm a Hobbyist with an interest in internals :-)