[Info-vax] OpenVMS Hobbyist licence - howto

[Steven Schweda]

Michael Kraemer wrote:
> Jan-Erik S�derholm schrieb:
>
> > It will probably "work" as long as you (or the OS) tries to
> > access (write) to some place > 1GB. At that time, the
> > write will wrap-around to the beginning of the disk.

   The OS is not the problem.

> I used all of the 2 and 4GB disk's space
> for Ultrix' partitions, no problems so far.
> Maybe the Ultrix installation doesn't use the VS's firmware
> the way VMS does?
> IIRC Ultrix boot prepares the installation in RAM
> before writing anything to disk, so it might be
> invulnerable to the firmware's limitations.

   As a little FAQ reading should reveal, the problem is not
with the OS, it's with the firmware using short-form SCSI
commands, which wrap at 1GB.  (Some older VMS versions have an
OS limit at 8GB.  I recall no 4GB limit anywhere.)  Using VMS,
as I recall, the troublesome firmware goes into action during
a crash dump.  I don't know if Ultrix had the same problem,
but I'd assume so.  So, everything will work fine with a
larger disk, until something goes wrong.  And then, if the
crash dump region on the disk is not within the first 1GB,
then you can expect something in the first 1GB to get dumped
onto.