Virtual memory routines on RSX

[Lee Gleason]

I was browsing the IAS/RSX system library routines manual today , and was
reading chapter 8, which describes a collection of routines to allow a task
to do its own paging-to-disk style virtual memory management.

Anyone ever seen these used? Have an opinion on whether they are useful?

--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.g...@comcast.net

[Rob Brown]

On 2012-09-04, Lee Gleason <lee.g...@comcast.net> wrote:
> Anyone ever seen these used?

Johnny has used them.

> Have an opinion on whether they are useful?

Last time I looked at them, I thought that they did not expand the
address space enough to make them worthwhile. I thought you could do
more with the PLAS directives, or even just a virtual array.

My 2 cents.

- Rob

[Johnny Billquist]

I wrote a rely to Lee, but I can't see it, so I don't know what happened
to it.

Anyway, yes, I've used the VM library. It's pretty ok, but it has a
couple of limitations that I find annoying.
1. You cannot free memory. Only allocate.
2. You cannot allocate more than 512 bytes in one chunk.

The VM library in turn uses the DM library, which is actually a very
useful and nice library.
PLAS directives are nice, but the problem with them is that all RSX
systems do not neccesarily have the PLAS directive.
Virtual arrays are pretty much no different than the VM library, but
more restricted.

With the VM library, you can pretty much have 128K of ram to play with
(if I remember right, but it might be that it is just 64K).

Some of the more known users of the VM library is MACRO-11 and TKB,
which uses them for the symbol tables and other information. Neither of
the restrictions mentioned above is a problem in this case.

IND uses the DM library only.

Johnny