Subject: Re: When it rains VAXen it pours VAXen....(:+}}...
To: None <>
From: Carl Lowenstein <>
List: port-vax
Date: 10/12/2000 11:56:20
> From Thu Oct 12 09:59 PDT 2000
> From: NetBSD Bob <>
> Subject: When it rains VAXen it pours VAXen....(:+}}...
> To:
> Date: Thu, 12 Oct 2000 13:03:48 -0400 (EDT)
> Questions about setting the thing up, and maximizing its capability:
> 3.  How many scsi drives will the thing actually handle?  It has
>     1 spare bay where the old crazy DEC dual floppy went, and
>     it has three spare bays under the TK70 tape bay.  Logic would
>     say 4 drives would work, but what will that power supply really
>     handle (horror stories of burning MVI crates kind of thing)?
>     How many drives can NetBSD handle off of one controller, if I
>     put in modern half-heights with power Y connectors (6 maybe)?

Remember that the original cabinet was designed in the days when
MFM drives drew about 30 watts apiece.  Modern half-height SCSI
drives draw 8 to 12 watts, exept for the really high-performance
ones.  SCSI controllers generically speaking can handle 7 drives.

> 4.  The original 12 foot twisted pair scsi cable only had one connector
>     on it, and when I took it by the local cable monger's shoppe to get
>     extra connectors added, they could not get the wires to line up 
>     into the modern 50 pin connectors.  I picked up a modern 4 header
>     scsi cable, and I am assuming that would work correctly at the slow
>     speeds on the MVII bus?

12-foot SCSI cable?  Where did it run (to, from)?

The SCSI speed will be determined by the controller you have.  (by the
way, what kind is it?)  Probably not faster than 5MHz byte rate.  At
this speed, flat ribbon cable will be good for at least 10 feet.
Plenty enough to run around the inside of a BA123.  Just be sure to
grab on to as many 50-pin SCSI drives as you can, because they aren't
making them any more.  And remember that newer SCSI drives are in
general backwards compatible with older controllers.

> 5.  What is needed to hook up a second tape drive into the thing?  I have
>     a spare TK50 that I would like to try adding into the machine where
>     the old floppy went, as a secondary tape drive for writing boot tapes.
>     Anything strange in adding a TK50 where the old floppy went?
>     (Dip switch addressing and that kind of thing?)

You need another TQK50 controller to use another TK50 drive.
If you are really lucky, your SCSI controller, besides emulating MSCP
for disk drives, will also do TMSCP for tape drives.  Then you can
use any modern DAT drive.

> 6.  On a lark, what would be needed to hook up a floppy of some sort
>     into the old dual floppy bay?  Would something like that boot the
>     old Ultix-32M boot floppies?  Can an ordinary AT drive be used or
>     does it need the original DEC dual floppy thing?

Again, you need a controller.  The original DEC floppy drive was
controlled from the RQDX3 or RQDX2 controller which also ran the
original DEC RD53 or RD54 hard drives.

> 9.  What is needed to hook up external 9 track reel-reel drives on this
>     critter?  One of my goals is to write some ancient UNIX 9 track boot
>     tapes, if possible.

A Qbus controller that emulates TMSCP to the CPU and (probably) Pertec
high-level interface to the tape drive.  Or a tape drive that has a
SCSI interface.

> 12. What were the prom commands for the KA630?  The only thing I could
>     get it to do was boot.  Veddy dumb, even compared to the KA640 cpu.
>     No show dev and no test 75 even.  How does one low-level format on
>     the MVII (from the diags tape?)?

START, UNJAM.  Nothing much more.  You do low-level format from the
diagnostic tape if you have the Field Service version, the Customer
version is pretty useless.


        carl lowenstein         marine physical lab     u.c. san diego
        {decvax|ucbvax} !ucsd!mpl!cdl