UDA50/RA81 problems....

[rbbb at RICE.ARPA]

From:  David Chase <rbbb at RICE.ARPA>

To remove some of the mystery (not all):

1) UDA "microcode" bugs:
Check your UDA boards - if they are M7161 and M7162, then they are OLD;
if they are M7485 and M7486, then they are NEW.  I don't think there are
many old boards out there anymore, since DEC (at least in our part of the
world) went around upgrading the disks on some sort of schedule.  We may
have unusually responsible field service out here, since everyone else tells
horror stories.  Whatever version of the driver we are running (for 4.2)
doesn't knock the disk offline; uda.c claims it is revision 2.1 84/03/05,
and has the unfortunate comment "TO DO: write the bad block forwarding code".

2) Information about these devices can be had from DEC; here are the order
numbers and the address:

EK-UDA50-UG-002 UDA50 User Guide (mostly hardware info)
AA-L619A-TK     MSCP Basic Disk Functions Manual
AA-L620A-TK     Storage System Diagnostic and Utilities Protocol
AA-L621A-TK     Storage System UNIBUS Port Description

I have the first manual, but not the other three.  The last three may be
ordered as a kit,

QP905-GZ        UDA50 Programmer's Documentation Kit.

The address is:

Software Distribution Center
Order Adminstration/Processing
20 Forbes Road (NR4)
Northboro, MA 01532

3) Deuna information (lots of it) EK-DEUNA-UG-001 Deuna User's Guide.  Why
anyone would use a Deuna when Interlan boards are available is beyond me,
since the Deuna draws about twice as much of everything from the Unibus, and
prefers the official DEC H4000 transceiver.  Xerox makes one about as big as
my fist that seems to work with the Deuna and its diagnostics, except that
it lacks the H4000's bogus "heartbeat" (the transceiver asserts "collision"
in a special window to let the controller know that its collision detector
is still working.)

For high density applications ethernet, I recommend DEC's DELNI.  It
provides 8 connections for a single network tap.  It can also operate
without any ethernet connection (providing a cheap 8 node psuedo-ethernet)
and (if not connected to ethernet) can be tiered to support up to 64 nodes.
Cable length restrictions would probably make a 64 node DELNI network a
little silly, but it is possible.  We have 5 diskless Suns connected to a
net through one of these, and have had no trouble from the DELNI.  I also
recommend this because we have had significant (more than once) problems
with bad connections to the ethernet cable itself (sometimes shorting the
cable), and people using the network get unhappy.

4) 750 hardware information (this might solve some of the WCS questions,
though not how to deal with the DEC-supplied updates), EK-KA750-TD-002 (not
necessarily the latest edition).  This is NOT for the faint of heart.

Now, does anyone out there know any good rumors about "fast fork" for 4.2+n?
This uses copy-on-write shared memory; we once heard that this would require
a microcode update and was thus delayed.  I didn't understand that rumor,
since it seems doable with software.  Any comments?

5) There is a TM78 (the TU78/TA78 formatter) microcode upgrade floating
around; it doesn't break the 4.2 driver (it changed EOT processing in some
way, I think to report EOT before any io errors; this helps VMS backup not
embarrass itself by running off the end of the tape).  We also received this
upgrade on some schedule, I think determined by our drive serial number.

Hope this clears up some of the hardware confusion out there.

drc