low-end vaxen and unix

[Michael Sokolov]

Pat Barron <pat at transarc.com> wrote:

> As I recall, you can attach an external SCSI hard disk to a MicroVAX 2000,
> and Ultrix will be able to use it, but you can't boot from it.  The
> Centronics expansion port really is a SCSI port, even though it was never
> billed as such (and the TZK50 tape drive really is a SCSI drive, and you
> can use it on other systems that have SCSI - not sure why you'd want to,
> though....).

Correct, except that since Ultrix is binary-only chainware, you would have to
disassemble and patch some of its kernel .o files in order to force is to
recognize SCSI disks. It uses the CPU code (a byte-sized number constructed
from the SID and SID extension longwords) to index into a table of pointers to
routines for different CPUs, and the routines that get called when the CPU is
KA410 (VS/MV 2000) don't bother to probe for SCSI disks. This means that any
SCSI disks you may have attached will be silently ignored, even though the
drivers are present and they would work if they weren't artificially blocked.

> 4.3BSD (and its variants) for the VAX has no SCSI support at all, so
> you're out of luck if you want to use SCSI disks on a MicroVAX under 4.3.

Adding BabyVAX support (with MFM, SCSI, LANCE, and everything) to
4.3BSD-Quasijarus is in my plans. For more information, subscribe to the
Quasijarus mailing list.

If you want to have something running now, you can either run Ultrix and learn
to live in binary-only chains, or you can construct a system consisting of the
Ultrix kernel and the 4.3BSD-Quasijarus userland. There is enough syscall
compatibility between 4.3BSD and Ultrix to make this possible.

Michael Sokolov
TUHS 4BSD Coordinator
4.3BSD-* Maintainer
Quasijarus Project Principal Architect & Developer
Phone: 440-449-0299 or 216-217-2579
ARPA Internet SMTP mail: mxs46 at k2.scl.cwru.edu
TUHS WWW page: http://minnie.cs.adfa.edu.au/TUHS/
Quasijarus WWW page: http://minnie.cs.adfa.edu.au/Quasijarus/

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