Introduction and need help bringing some pdp11's back

[allison]

On 10/29/19 8:37 PM, Chris Zach via cctalk wrote:
>> I assume your building up a Qbus PDP-11.
> 
> Yup. They're easier to get going for starters and since I got rid of the
> 11/44 the fastest system I've got.

I like them for the many flavors of CPU and and possible configurations.
I have a few really one of every possible base PDP-11 and a few MicroVax
cpus.

> 
>> To go from RQDX3 to any drive you need a distrbution panel as used in
>> BA23 or M9058 distribution board usually used in BA123.
> 
> Yup, got one of those in the BA23. Oh, are the floppies DU0/DU1 with the
> disk drive DU2 or is it different?

Memory test.  Look up the standard jumpers. Should be in the MicroPDP-11
handbook or slipcase doc set.

>> The M9058 can plug in to any general slot in Qbus for power and does not
>> past interrupt or DMA grant.  Bottom/end of the bus is fine.
> 
> Interesting, I didn't realize the RQDX series boards didn't use
> interrupts or DMA. Does the CPU just poll them endlessly?

Oh yes they do!   The breakout board m9058 is a dumb beast.
The RQDX3 is M7555.

And yes you can put a RQDX3 and M9058 in a BA23 for a three drive system
using half height drives (two st225 or st250 and a RX33).  That is not
documented but works just fine.

>> Then you need a 50 wide cable from RQDX3 to the distribution board and
>> the cable to match floppy from the distribution board (usually 34 wide).
> 
> Got that. The floppy cable I have has a twist between the second and
> third plugs, but I'm using the straight section only.

The twisted cables are for PCs only the rest of the world never did
that.  Reason if you did it the normal way you could have up to four
drives (but you had to setup the jumper/dip-switches) the twisted scheme
maxed at 2 (no setup as both drive were the same).

>> Jumper details are up to  you to slug out but I have two systems using
>> the RQDX3 and M9058.  I also have the Micro PDP-11 using the ba23
>> distribution.   Don't ask right now I can not get to them for the next
>> month.  Drive jumpers have to be correct.
> 
> For the RX50's were there any jumpers? If I'm still fiddling with this
> in a month I might ask for a pic of the configuration.

If no one played with the RX50s (and they actually work) it should be
plug and play. About half the RX50s I see are not functional and that
was more than 25 years ago and it cannot have gotten better.  Ir you
end up with a pile you can play mix and match and maybe get lucky.

Yes I believe two of them one being drive select.  Right now I can maybe
touch them, open them up for PICs, your kidding. ;)

I'm overhauling space (one 10x14 room) that has both lab, office and
ham radio... and a 50" rack of PDP11/73, BA123 MicoVAXII, and 10
Microvax3100s of multiple flavors, 2 MV2000s (one to format media and
the other runs ultrix 4.2) plus a few Linux PCs to do day to day stuff.
Then there is the S100 collection.

>> All of this is in the various manuals but no single one!
> 
> The RQDX3 was kind of out of my price zone the last time I worked on
> this stuff. The ESDI controller is extremely fast (and does elevator
> seeks so it rocks on RSX11) but doesn't have floppy support.
> 
> I'll see if I can dig out/find any of my RQDX1 boards to cross-check the
> RQDX3. Any of them should be able to run a RX50 (and lord be told I have
> RD52 and RD53 drives around here....)
> \

RQDX1 is in compatable with RQDX3 formatted RD disks!  best leave that
one alone.

I was lucky being both Ex-Digit (former dec) and in the immediate area
so finding stuff years ago was easy and free.  Long since dried up.

best advice is get DOCs, as much and varied of the QBUS PDP-11 family
and the various packaged systems as you can find or on line. Oh the
nasty part, you will have to actually read them to find a lot of the
details.

Allison