SCSI options for PDP 11/23

From: Jerome Fine <jhfine_at_idirect.com>
Date: Thu Feb 28 11:42:06 2002

>Tom Leffingwell wrote:

> After my recent RX02 problems, I've decided I'd like to add a SCSI
> controller in my 11/23, and keep my programs on a hard disk. What Q-bus
> controllers will work with RT-11? What's the minimum version of RT-11
> that I can get by with? Can I use any disk, or does it have to be
> something in particular?

Jerome Fine replies:

As Zane has answered, the CMD and Viking host adapters will work
with RT-11, although I had not remembered that the Viking brand
work only in a 22-bit backplane. I once used a Sigma MFM
controller and it also required a 22-bit backplane.

What Zane did not mention (as you will find out if you ask for prices)
is that the CQD-220/M (disk only) or CDQ-220/TM (Disk and Tape)
host adapters are still expensive for a hobby user - normally in the
range of about $ US 800 to $ US 1200 depending on model and
availability.

So while the SCSI hard drives are almost free - I acquired ten
ST32550N drives for less than $ 15 each (and that was probably
an overpayment - although shipping was zero), the host adapter
for a Qbus is not.

As Zane said, V5.00 is required, although there were too many
bugs in the first few versions. I would recommend AT LEAST
V5.03 of RT-11 for hard drive use and V5.04C for tape use.

Your problem will be making a copy of the newer V5.03 to
a SCSI hard drive. Once that is done, the device driver
for DY(X).SYS in V5.03 will handle the RX02 in the
normal fashion and use the existing 3rd party hardware
without any problems.
Received on Thu Feb 28 2002 - 11:42:06 GMT