1 Jun
2011
1 Jun
'11
10:23 a.m.
On 2011-06-01 10.00, Ethan Dicks<ethan.dicks at gmail.com> wrote:
On Wed, Jun 1, 2011 at 3:19 AM, Pete Turnbull<pete
at dunnington.plus.com> wrote:
> > On 01/06/2011 03:21, Jerome H. Fine wrote:
>> >>
>> >> For those of you who have heard about a mythical
>> >> SIX ?BUTTON ?FRONT ?PANEL for the BA23,
>> >> it does exist and actually works.
> >
> > Mythical? ?I've probably seen more BA23s with a 6-button panel than
without,
> > and both my BA23s have 6-button panels.
Yeah. Nothing mythical about the 6-button panel. Glad to see that I'm
not the only one thinking so.
I remember_trying_ to put two hard disks in one
machine for quick
disk-to-disk copies. I have a fuzzy memory that it didn't work for
me, but I don't remember whacking either drive to the point that they
didn't work when returned to their former homes.
As far as I know, the BA23 backplane distribution panel can *not* be
used for two disk drives. I know there is a DEC note/article about this
not working. You need the external distribution board for the RQDX3 to
use two drives. If you use the BA23 backplane distribution panel with
two harddisk drives, you have a high chance of corrupting both disks.
(If I remember right, the write gate signal somehow goes to both disks,
no matter what, which cause the disk to possibly start writing when the
disk is seeking, for example. Very bad.)
The BA23 backplane distribution should only be used for one harddisk,
and possibly one floppy.
Johnny
1 Jun
1 Jun
11:09 p.m.
Johnny Billquist [bqt at softjar.se] wrote:
As far as I know, the BA23 backplane distribution
panel can *not* be
used for two disk drives. I know there is a DEC note/article
about this
not working. You need the external distribution board for the
RQDX3 to
I used several configs in the DEC lab with 2 RD54s in a BA23 for years
and never hit a problem. (Mind you, I also had a KDA50 in a BA23, so
I'm not saying you should do this at home :-)).
If there's a note, I'd like to see it sometime ...
Antonio
arcarlini at iee.org
11:10 p.m.
Two hard drives in a BA23?
Provided you don?t want to connect to another BA23 or use a non-DEC disk
controller then a brace of DEC SCSI drives and a flat SCSI cable will do it.
I think the drive power cables come direct from the PSU. If so, then you can
rip out the backplane and card guides. The guides can be used to make
storage units for PC cards. You can use the back plane to make a real 'open'
system i.e. one you can get at the pc cards.
?
Rod Smallwood (DEC 1975 -1985)
?
?????
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Johnny Billquist
Sent: 01 June 2011 18:23
To: cctalk at classiccmp.org
Subject: Re: SIX Button BA23 Front Panel
On 2011-06-01 10.00, Ethan Dicks<ethan.dicks at gmail.com> wrote:
On Wed, Jun 1, 2011 at 3:19 AM, Pete Turnbull<pete
at dunnington.plus.com>
wrote:
> > On 01/06/2011 03:21, Jerome H. Fine wrote:
>> >>
>> >> For those of you who have heard about a mythical
>> >> SIX ?BUTTON ?FRONT ?PANEL for the BA23,
>> >> it does exist and actually works.
> >
> > Mythical? ?I've probably seen more BA23s with a 6-button panel than
without,
> > and both my BA23s have 6-button panels.
Yeah. Nothing mythical about the 6-button panel. Glad to see that I'm
not the only one thinking so.
I remember_trying_ to put two hard disks in one
machine for quick
disk-to-disk copies. I have a fuzzy memory that it didn't work for
me, but I don't remember whacking either drive to the point that they
didn't work when returned to their former homes.
As far as I know, the BA23 backplane distribution panel can *not* be
used for two disk drives. I know there is a DEC note/article about this
not working. You need the external distribution board for the RQDX3 to
use two drives. If you use the BA23 backplane distribution panel with
two harddisk drives, you have a high chance of corrupting both disks.
(If I remember right, the write gate signal somehow goes to both disks,
no matter what, which cause the disk to possibly start writing when the
disk is seeking, for example. Very bad.)
The BA23 backplane distribution should only be used for one harddisk,
and possibly one floppy.
Johnny
2 Jun
2 Jun
12:20 a.m.
On 01/06/2011 18:23, Johnny Billquist wrote:
Yeah. Nothing mythical about the 6-button panel. Glad
to see that I'm
not the only one thinking so.
Although some manuals do mention that you should only use one hard drive
in a BA23 (eg the Maintenance Manual) I've seen several systems --
including mine -- do so with no problem. I've never seen a problem with
Write Gate, nor would I expect to. Like all other ST412-type
interfaces, the M9058 distribution card has the same write gate signal
wired to all the 34-pin HDD connectors in parallel. In fact the /only/
control signals not wired strictly in parallel on those connectors are
some of the drive selects.
What I do know is that the docs say you must draw no more than 7A from
the 12V supply in a BA23, and one RD51 takes 4.5A. So 2 x RD51 would
overload it. I believe that's the only restriction, because putting a
second RD5x in a BA23C expansion box, connected via an RQDXE, was
supported -- and AFAIR the RQDXE doesn't do anything clever with the
control or status signals.
--
Pete Peter Turnbull
Network Manager
University of York
I remember_trying_ to put two hard disks in one
machine for quick
disk-to-disk copies. I have a fuzzy memory that it didn't work for
me, but I don't remember whacking either drive to the point that they
didn't work when returned to their former homes.
As far as I know, the BA23 backplane distribution panel can *not* be
used for two disk drives. I know there is a DEC note/article about this
not working. You need the external distribution board for the RQDX3 to
use two drives. If you use the BA23 backplane distribution panel with
two harddisk drives, you have a high chance of corrupting both disks.
(If I remember right, the write gate signal somehow goes to both disks,
no matter what, which cause the disk to possibly start writing when the
disk is seeking, for example. Very bad.) 
6:29 p.m.
Pete Turnbull wrote:
What I do know is that the docs say you must draw no
more than 7A from
the 12V supply in a BA23, and one RD51 takes 4.5A. So 2 x RD51 would
overload it. I believe that's the only restriction, because putting a
second RD5x in a BA23C expansion box, connected via an RQDXE, was
supported -- and AFAIR the RQDXE doesn't do anything clever with the
control or status signals.
I checked the drive specs in the BA23 manual.
I don't know if the values are correct, however,
the manual lists 2.5 Amp on the 12 volt.
However, in any case, from my point of view,
it is far better to use an additional PC power
supply (for just the hard drives) when there
are two hard drives used in a BA23 box.
This take the load off the internal power supply.
And if you want to use an RX50 and a TK70
as well, then you would almost certainly exceed
the 7 Amp available on the 12 volt internal
power supply. As I mentioned, always use
the internal power supply for the TK50 / TK70.
Whereas I leave the RX50 outside the BA23
box if there is no TK70, with a TK70 I usually
place the RX50 and TK70 inside the BA23
box and the 2 hard drives outside the BA23
box.
Jerome Fine
3 Jun
3 Jun
12:13 a.m.
On 03/06/2011 02:29, Jerome H. Fine wrote:
I got the 4.5A from the microPDP-11 Systems Maintenance Guide, which
happened to be the nearest to hand when I wrote that. It might not be
correct; it does seem a lot even for such an old drive. I've just
looked hrough some other manuals
Incidentally, that Maintenance Guide is the same manual which (on page
8-14) tells how to set the drive select jumpers for DU0: and DU1: in a
BA23. Although it also says (on page 5-6) only to install one RD52 in a
BA23 :-)
Pete Turnbull
wrote:
What I do know is that the docs say you must draw
no more than 7A from
the 12V supply in a BA23, and one RD51 takes 4.5A. So 2 x RD51 would
overload it. I believe that's the only restriction, because putting a
second RD5x in a BA23C expansion box, connected via an RQDXE, was
supported -- and AFAIR the RQDXE doesn't do anything clever with the
control or status signals.
I checked the drive specs in the BA23 manual.
I don't know if the values are correct, however,
the manual lists 2.5 Amp on the 12 volt. However, in any case, from my point of view,
it is far better to use an additional PC power
supply (for just the hard drives) when there
are two hard drives used in a BA23 box.
This take the load off the internal power supply.
I don't bother doing that, but...
And if you want to use an RX50 and a TK70
as well, then you would almost certainly exceed
the 7 Amp available on the 12 volt internal
power supply. As I mentioned, always use
the internal power supply for the TK50 / TK70.
Whereas I leave the RX50 outside the BA23
box if there is no TK70, with a TK70 I usually
place the RX50 and TK70 inside the BA23
box and the 2 hard drives outside the BA23
box.
...my 11/83 has two RD drives in the BA23 running off the internal
supply, and (when I got it) had an external RX50 which had its own PSU.
--
Pete Peter Turnbull
Network Manager
University of York
7:26 a.m.
Pete Turnbull wrote:
I got the 4.5A from the microPDP-11 Systems
Maintenance Guide, which
happened to be the nearest to hand when I wrote that. It might not be
correct; it does seem a lot even for such an old drive. I've just
looked hrough some other manuals
I believe that I actually measured the current
at one point. It was initially 2.5 Amp on the
12 volt, then about 1 Amp after that.
Incidentally, that Maintenance Guide is the same
manual which (on page
8-14) tells how to set the drive select jumpers for DU0: and DU1: in a
BA23. Although it also says (on page 5-6) only to install one RD52 in
a BA23 :-)
Whenever I use 2 hard drives on a BA23 for
more than about 1 hour, I always use an additional
PC power supply just for the hard drives.
As for an RD5n or RD3n on an RQDXn, the BA23
circuits fully support 2 hard drives with a 6 button
front panel. In my experience, it is the 12 volt current
that is the problem. Just be sure to use DS3 for
drive 0 and DS4 for drive 1.
However, in
any case, from my point of view,
it is far better to use an additional PC power
supply (for just the hard drives) when there
are two hard drives used in a BA23 box.
This take the load off the internal power supply.
I don't bother doing that, but... And if you
want to use an RX50 and a TK70
as well, then you would almost certainly exceed
the 7 Amp available on the 12 volt internal
power supply. As I mentioned, always use
the internal power supply for the TK50 / TK70.
Whereas I leave the RX50 outside the BA23
box if there is no TK70, with a TK70 I usually
place the RX50 and TK70 inside the BA23
box and the 2 hard drives outside the BA23
box.
...my 11/83 has two RD drives in the BA23 running off the internal
supply, and (when I got it) had an external RX50 which had its own PSU.
2 Jun
2 Jun
6:39 p.m.
Johnny Billquist wrote:
Yeah. Nothing mythical about the 6-button panel. Glad
to see that I'm
not the only one thinking so.
The 6 button front panel on the BA23 box is specifically
for when there are 2 MFM RD5n / RD3n hard drives.
For a system using all DEC hardware in an approved
configuration, the 1/2 height MFM RD3n hard drives
can be stacked so that 2 hard drives will fit in one bay.
I remember_trying_ to put two hard disks in one
machine for quick
disk-to-disk copies. I have a fuzzy memory that it didn't work for
me, but I don't remember whacking either drive to the point that they
didn't work when returned to their former homes.
As far as I know, the BA23 backplane distribution panel can *not* be
used for two disk drives. I know there is a DEC note/article about
this not working. You need the external distribution board for the
RQDX3 to use two drives. If you use the BA23 backplane distribution
panel with two harddisk drives, you have a high chance of corrupting
both disks.
(If I remember right, the write gate signal somehow goes to both
disks, no matter what, which cause the disk to possibly start writing
when the disk is seeking, for example. Very bad.) The BA23 backplane distribution should only be used
for one harddisk,
and possibly one floppy.
The BA23 box which includes an RD distribution panel supports
two hard drives and two floppy drives. The RX50 is a dual
drive in a single enclosure and counts as 2 floppy drives.
While support for 2 floppy drives is standard, support for
2 hard drives requires a 6 button BA23 front panel.
Jerome Fine
4951
days inactive
4953
days old
7 comments
5 participants
participants (5)
-
arcarlini＠iee.org -
bqt＠softjar.se -
jhfinedp3k＠compsys.to -
pete＠dunnington.plus.com -
rodsmallwood＠btconnect.com