9 Nov
2010
9 Nov
'10
8:39 a.m.
I am attempting to enhance a program which runs under RSTS/E, RTEM-11,
RT-11 and TSX-Plus. Thus far, I have managed to support these enhancements
for all but RTEM-11 due to the lack of documentation on RTEM-11. When
I requested help with supporting such programs under RSTS/E, John Dundas
provided a reference document which cleared up many questions.
Does anyone know of a document (and its link if it is on the internet,
especially
at bitsavers) which describes the support provided by RTEM-11 for programs
which also run under RT-11? From the comments that I have seen, the RT-11
operating system is run under RTEM-11 with special "hooks" to interface to
RTEM-11. If my understanding is correct, then all of the RT-11 EMT requests
supported by an RT11SJ monitor will also be available when running under
RTEM-11.
There are also two other specific questions that I suspect have a simple
answer:
(a) How much memory does a user program have which runs under RTEM-11?
My assumption is that a user program has approximately the same
size of
memory available when running under RTEM-11 as it would when running
under the RT11SJ monitor on a PDP-11 with 64 KBytes of physical
memory
which usually (when no additional device drivers are present)
ends up being
approximately 48 KBytes or an address range from 0 to about
120000 octal.
(b) Whereas RT-11 actively supports the ability of device drivers to be
LOADed
and UNLOADed at any time based on which devices are in active
use, RSTS/E
and TSX-Plus require the device drivers of any device that is
active to be
LOADed at all times. It would be an assumption on my part, but I
tend to
assume that under RTEM-11, any available devices are already LOADed
by the actual operating system that controls the CPU.
Specifically, if a user
program performs the .DStatus RT-11 EMT request for an available
device,
the 3rd word of the device driver information will always be
non-zero which
specifies that the device driver in question is always in memory
and that a
.Fetch RT-11 EMT request would be redundant.
Can anyone provide any documentation sources? If anyone knows the answer
to the approximate size of memory available to a user program running under
RTEM-11 and / or the answer concerning the LOADed status of a device driver,
it would be greatly appreciated.
Jerome Fine