[comp.sys.dec] RM02 on MASSBUS advice wanted.

geremin@decus.com.au (Big John from MEGATRONICS) (06/07/89)

Hello World, I am about to connect up a RM03 disk, an RM05 disk and a RM02
drive all on the same MASSBUS Controller on a PDP-1170 running RSTS v8.0.

I realize that the RM02 was intended to operate on a RH11 controller on
the Unibus of smaller PDP-11s with a slower transfer rate. I have them on hand
and cant afford to get them converted. And I dont mind the slower transfer
rate.

My question is: Does anyone know if there are any problems with this config.?

Thanks in advance, John G.          geremin@decus.com.au
--------------------------

craig@csdvx0.accu.csd.unsw.oz (Craig McGregor) (06/07/89)

In article <217@decus.com.au>, geremin@decus.com.au (Big John from MEGATRONICS) writes:
> Hello World, I am about to connect up a RM03 disk, an RM05 disk and a RM02
> drive all on the same MASSBUS Controller on a PDP-1170 running RSTS v8.0.
> 
> I realize that the RM02 was intended to operate on a RH11 controller on
> the Unibus of smaller PDP-11s with a slower transfer rate. I have them on hand
> and cant afford to get them converted. And I dont mind the slower transfer
> rate.
> 
> My question is: Does anyone know if there are any problems with this config.?
> 
> Thanks in advance, John G.          geremin@decus.com.au
> --------------------------

We once moved an RM02 from a PDP-11/40 with RH11 to a VAX-11/750 with
RH750 and RM80 and it WORKED!!
I think that a jumper on the massbus board under the RM02 had to be moved
to alter some timing thing.
-- 
-----------------------------------------------------------------------
Craig McGregor  (Faculty of Architecture, University of NSW)
ACSnet:	craig@csdvx0.accu.csd.unsw.oz
Phone:	+61 2 697-4764		Fax:	+61 2 662-2264
-----------------------------------------------------------------------

naylor@decus.com.au (06/09/89)

In article <217@decus.com.au>, geremin@decus.com.au (Big John from MEGATRONICS) writes:
> Hello World, I am about to connect up a RM03 disk, an RM05 disk and a RM02
> drive all on the same MASSBUS Controller on a PDP-1170 running RSTS v8.0.
> 
> I realize that the RM02 was intended to operate on a RH11 controller on
> the Unibus of smaller PDP-11s with a slower transfer rate. I have them on hand
> and cant afford to get them converted. And I dont mind the slower transfer
> rate.
> 
> My question is: Does anyone know if there are any problems with this config.?
> 

Several moons ago I suceeded in doing just this. DEC F/S had never seen a mixed
massbus before, but they always need educating. I did it with RSX-11m+, which
is a superb O/S, so what I have to offer may not work with RSTS.

With RSX you have to re do sysgen and answer the question about mixed  massbus.
The real trick is that the last drive in the massbus chain MUST be an RM05.
It has to do with the MASSBUS timing signals (I forget which ones). In our
 config we had the RP04s and RM02's numbered 0-4 for each set. The sequence
 was...

RP0...RP2
RM0..RM3
RP3
MB terminator

The last RP04 ensures that the bus timing is held up thru the RM02's. 

It took us about an hour to figure it out (by trial and error) but we succeeded
and it ran well until we finally lost the 11/70.

Incidentally we used an RH70 controller not the RH11. We had an RH 11 on our
11/44 but never got to try the trick out on it.

Good luck !!

Richard Naylor				naylor@wcc.govt.nz
Computer Services Manager               0530147000090::naylor
Computer Services Section
Wellington City Council
New Zealand