Jerome H. Fine jhfinedp3k at
Sun Aug 9 19:01:26 CDT 2015

 >Pete Turnbull wrote:

> On 09/08/2015 18:14, Sean Caron wrote:
>> DEC did sell a version of the BA23 that was intended to be used just 
>> as an
>> expansion peripherals cabinet. You shouldn't have any problems 
>> putting HH
>> devices in BA23 bays (so long as you have the appropriate interfaces to
>> drive them) but you may need i.e. 3.5" to 5.25" bracket to attach to the
>> BA23 sleds, and you'll have (cosmetic) blank space on top after 
>> putting a
>> HH device in a FH bay. I imagine you'd have to make a special bracket to
>> mount a TZ30/RX33 over-under in one of the 5.25" bays in the BA23 but it
>> could certainly be done ... No such factory configuration exists AFAIK 
> If a TZ30 has the same mounting holes as a 5.25" disk drive, it's 
> doable.  There's an official DEC mounting kit to mount 2 x RX33 where 
> you'd normally find an RX50 in a BA23/BA123.  It's basically two side 
> plates, to hold the upper and lower drives together.

There is a very simple solution to mount 2 * RX33 floppy drives
if you have an old RX50 which no longer works - or you at least
can borrow the outer shell from a working RX50.  There is
sufficient room when 2 * RX33 floppy drives are stuffed into
an empty RX50 shell to hold the edge connectors along with
a Y power splitter.  Then use a few bolts to make the empty
shell rigid by attaching the now FULL RX50 shell (naturally
with the 2 * RX33 drives inside) to both RX33 drives plus
attaching the original black plastic sled to the bottom in its
original location.  I suggest that you first test everything out
to make sure that the connections are working before placing
the 2 * RX33 drives inside the empty RX50 shell.  Once
finished, the 2 * RX33 drives look very much like a dual
RX50, but the handles to lock in the floppy media give the
situation away on close inspection.  ALSO, it seems best
to mount both RX33 drives right-side UP.  The lower
handle works much more easily that way.  I still have my
dual RX33 set-up in this manner.  The only difference is that
the cable ends in two edge connectors rather than the
header used for the RX50.  So it does work.

This probably works since the RQDX3 is set to handle the
dual RX50, so having 2 * RX33 floppy drives is equivalent.
NOTE that the RX33 will work ONLY with the RQDX3,
not the RQDX1 or RQDX2.  In addition, with the RX33
drive, DEC actually supports the command to perform a
Low Level Format which was NEVER possible with the
RX50 drive with DEC hardware in a PDP-11 Qbus system.
Under RT-11, just FORMAT  DU0:

As far as 1 * RX33 and a TZ30, I imagine that would also
be fairly easy as well, although I don't know how much
clearance is available inside the empty RX50 shell for the
cable to the TZ30 tape drive.  If someone actually attempts
to place both the RX33 and the TZ30 inside the RX50 shell,
please let us know what happens.

Jerome Fine

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