DEC RQZX1 and KDJ11-E boot problem?

Johnny Billquist bqt at
Sat Jun 19 12:53:53 CDT 2010

"Zane H. Healy" <healyzh at> wrote:
> Now for an interesting bit of info.  Apparently there are two 
> different types of Firmware.  One for the PDP-11, and one for VAXen. 
> I'll see if I can get a little bit more info on that.

Huh? That sounds extremely weird, and until you find very good proof of 
that, I would say that it is false. In the end, it's a Qbus device, and 
talks Qbus just like anything else. It's also an MSCP controller, which 
means it talks MSCP, just like any other MSCP controller. And they work 
the same no matter if they are controlled by a VAX CPU or a PDP-11 CPU.

> Now for the important part, the whole manual.

Excellent! Thanks for putting this up there.

> Looking through the list of supported hardware I see where this is a 
> board that is of use to very few Hobbyists.  It is interesting that 
> the older versions of the OS's can't support it, when they support 
> something like a Viking QDT just fine.

It is worth pointing out that support OS versions is just a list of the 
versions that was current when the manual was written. That does not 
mean that the board don't work in previous versions.
The RQZX1 is an MSCP/TMSCP controller, and thus will work with any OS 
version where the MSCP/TMSCP driver exist, and work. So, it's no 
different than the QDT, or any other MSCP controller.

More or less the same is also true for disk drives. Most any SCSI drive 
will work fine. The same is probably also true for tape drives.

Pros with the RQZX1:
It's easy to set up. Switchpacks are easy and obvious. You can boot into 
the internal diagnostics. You have the option of 2*MSCP or MSCP+TMSCP. 
You have a floppy interface in there as well.

Cons with the RQZX1:
It's a quad board. No more than 4 disks on one controller. No more than 
one tape on a controller (it is rather inflexible).

Still, if you have one, it's a nice board to have around.


More information about the cctech mailing list