30 Jun
2009
30 Jun
'09
7:35 p.m.
I am NOW holding a 6-button front panel for the BA23 in my hands:
P/N 70-22007-02
REV. B1 ECO
MFG. KAO 49/87
Right-Hand Number which is vertical is 90-09255-04
After removing the 4 bolts on the back, the PCB board:
BA23 FRONT PANEL
KA 54-16458-02 8150/87 (last 4 characters hand written in ink)
Left-Hand Number which is vertical is 5016457
The labels for this panel are:
Fixed Disk 1 Fixed Disk 0
Write Protect Write Protect Halt
Run
@ @ @ o
Ready Ready Restart
DC OK
@ @ @ o
where: @ is a push-button switch and o is a green LED
NOTE: I have never tested this 6-button front panel with a BA23
box, so I do not know if it functions correctly as would be expected
from the labels. In addition, since DEC manufactured
an RQDXE
board which specifically provided for Fixed Disk 1 to be supported
by an RQDXn, it seems reasonable to assume that the 6-button
front panel could handle TWO hard drives and that DEC supported
this configuration with the Fixed Disk 1 being held in an expansion
BA23 box. This would allow 2 additional 5 1/4" drive bays, one
in the first BA23 box and the second in the expansion BA23 box,
to hold other drives such as an RX50 floppy drive and a TK50 tape
drive. What I do NOT know is which connectors should be used
on the BA23 Signal Distribution Panel in the BA23 expansion box,
i.e. the Fixed Disk 0 pair of connectors or the Fixed Disk 1 pair of
connectors. If anyone has ever placed a Fixed Disk 1 in a BA23
box or knows of any documentation which provides the answer,
please HELP!!!!!!!!!!!!!!!
Alternatively, if the first (perhaps only) BA23 box is used to hold both
Fixed Disks, the Signal Distribution Panel at the rear of the compartment
can be used to connect the Fixed Disks to the RQDXn controller.
The metal bulkhead is clearly marked with the connectors to be
used for Fixed Disk 0 and Fixed Disk 1.
If an RX50 floppy drive is also required and a second BA23 box
is not present, then it would be possible to run the required cables
from a BA23 box out to an external location to an RX50
floppy
drive. While not the best solution, I would deem it to be acceptable
since the RX50 is an enclosed box.
CRITICAL INFORMATION: The Fixed Disk 0 MUST be
selected as DS3 and the Fixed Disk 1 MUST be selected as DS4.
Failure to do so will almost certainly result in a loss of FORMAT
for both of the Fixed Disk drives.
Finally, while there are no LEDs to provide information about the
WRITE PROTECT status of the media in a floppy drive, I am
confident that an RX50 drive could be connected in addition to
a Fixed Disk 0 and a Fixed Disk 1. However, the unit numbers
for the floppy media will (if both Fixed Disks are present) be set
as 2 and 3.
I realize that the above information is not a specific response to
the discussion below, however, it does pertain to the use of TWO
Fixed Disks along with the facts of what is probably needed to
operate Fixed Disk 0 and Fixed Disk 1 using either a single BA23
box or 2 BA23 boxes.
In my previous e-mail, I discussed my experience in using TWO
Fixed Disks with a 4-button front panel in a single BA23 box.
I also added my expectation of what would likely be the usage
when 2 BA23 boxes are used with TWO Fixed Disks.
Sincerely yours,
Jerome Fine
Pete Turnbull wrote:
On 19/06/2009 17:38, Johnny Billquist wrote:
This was definitely in a 4-butten front panel
BA23. However, I'm not
sure the front panel is the only place to blame.
It's not to blame at all. It has nothing to do with the drive selects.
It might stop a drive working reliably, but it definitely cannot cause
two to be selected at the same time. All it can do is tell the RQDX not
to use the drive.
*Maybe* the fact that the Ready/Write Protect
lines
for the 2nd drive are left floating, is somehow confusing
the RQDXn controller, but that seems doubtful.
The RQDX wasn't confused. It was the drives... When the RQDX started
writing to #0, the write circuitry of #1 also went active. Or if it
was writing to #1 which also activated the circuitry of #0.
Those lines merely report status of the 2nd
drive.
The Drive Select and Head Select lines don't go
anywhere near the front panel, and there are
separate signal lines for drives 0, 1, 2, and 3.
Exactly. Which is why I wonder if the front panel really is to blame
for the problem. Hmm. As far as I can remember, there are no DS
jumpers on the drives.
If you have an RQDXE, you have a bunch of jumpers on that in order to
set up which drive is which, and all that.
Not entirely. It's intended to provide sufficient connectors and to
route the some DS lines (etc) to the external unit. That doesn't
remove the need to set the DS jumpers on the drive(s) correctly.
But the backplane of the BA23 don't have any
jumpers, as far as I can
remember.
That's right, the backplane doesn't.
And in this case, both drives were RD53s.
Properly formatted, DEC
branded and everything.
Well, those drives definitely have Drive Select jumpers. Look at the
legend on the PCB by contact numbers 32 to 26 on the 34-way connector.
They're the drive select lines, and you'll see they're labelled, and
they go to a set of jumpers right beside the connector position, next to
the terminator resistor pack. If they were "as supplied by DEC" and the
person who installed them assumed the arrangement for a BA23 should be
the same as for a BA123 and didn't change one, they would both be set to
DS3, and so of course they both were selected at the same time. User
error, pure and simple.
The microPDP-11 Maintenance manual says where they are, and moreover
it says:
Always place the first fixed-disk drive in port 0 (left mass
storage slot of the enclosure containing the RQDX controller.
Set the device select to DS3 on any fixed disk installed in port
0 of the enclosure or expansion unit.
Set the device select to DS4 on any fixed disk installed in port
1 (right mass storage slot) of the enclosure or expansion unit.
This rule also applies to any subsystem installed in a BA23
enclosure.