How to boot VAX750 TMSCP from a TU-81

[Chris Torek]

In article <3593 at excelan.UUCP> tran at na.EXCELAN.COM (Tony Tran) writes:
> How does one boot the miniunix from a TU-81 tape
> on  an old VAX 750? Our vmunix is corrupt, and
> we cann't seem to boot from this new tape drive
> which is not supported by a VAX 750.

This is in fact a `wizard' question.  I have redirected followups to
comp.unix.wizards.

The TU81 is a TMSCP tape.  I do not understand the comment `not
supported by a VAX 750'; however, the tmscp driver supplied with 4.3BSD
and 4.3BSD-tahoe has only been used on TK50s on Microvax IIs, as far as
I know.  The driver does NOT work for TMSCP TK70s on Microvax 3x00s,
and in any case should be replaced completely (this is likely to be
simpler than fixing it, and certain to result in a better driver---even
that bastion of bad drivers%, Digital Equipment Corp., threw out the
old MSCP and TMSCP drivers for Ultrix 3.0).
-----
% See, e.g., the Ultrix QDSS driver included in 4.3BSD-tahoe.  I wrote
  one that compiles to 1/2 as much code, yet does more. . . .
-----

If you do not have a console TU58 cassette, or if your console cassette
is not functional, the only possible boot path is to enter raw VAX
codes via the console.  The `Installing 4.3BSD' document includes
code to boot from various devices, but TMSCP devices are not among
them, simply because the <expletive> protocol is so complicated.
If you are in such a situation, the best approach is to beg, borrow,
or steal other hardware with which to boot, or to do same to obtain
a working Ultrix 1.x or 2.x kernel and root file system.  The latter
method works for almost any VAX hardware: I used Ultrix 2-point-
something as the boot loader for my experimental 4.3BSD-tahoe-ish
kernels when porting the system to the VAX 8250.

Once you have the machine running, *make boot media*.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris