Douglas Taylor dj.taylor4 at
Sun Aug 9 21:14:13 CDT 2015

On 8/9/2015 8:01 PM, Jerome H. Fine wrote:
> >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

Interesting solution, the reason I asked is because I have a floor 
mounted BA23 PDP11 and a RQZX1 controller which will run a floppy, disk 
and tape.  I think it will run a TZ30 tape, haven't tried yet.

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