RLV11 in VAX 4000-400?

From: Peter Turnbull <pete_at_dunnington.u-net.com>
Date: Fri Jul 11 02:17:00 2003

On Jul 11, 7:50, Jochen Kunz wrote:
>
> Can I use a RLV11 in a VAX 4000-400?
>
> The pdp11-field-guide.txt says:
> RLV11 RLV11 Q RL01/02 disk controller option, consists
of
> RLV11 modules M8013 and M8014. Q/CD-only
option.
> RLV11 18-bit DMA only. Caution: uses BC1 and
BD1
> RLV11 for purposes other than BDAL18 and BDAL19
>
> The VAX 4000-400 has a 22 bit Qbus (all slots are Q/CD). So it looks
> like this can't work due to the 22 bit bus that uses BC1 and BD1?

The best solution is to use an RLV12. However I vaguely remember
seeing somewhere an ECO which involves cutting two tracks, to
disconnect the signals the RLV11 puts on the BC1 and BD1 fingers
(unless I'm thinking of some other device). That fixes the electrical
problem, but whether you can find a VAX OS that knows to only use DMA
in the bottom 256K of memory is another matter.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York

Received on Fri Jul 11 2003 - 02:17:00 BST