SCSI Questions (Was: "Re: Purchased a Microvax 3800")

Mark G. Thomas Mark at
Tue Dec 8 11:44:31 CST 2015


On Mon, Dec 07, 2015 at 02:25:25PM -0500, Christian Gauger-Cosgrove wrote:
> On 6 December 2015 at 13:24, Mark G. Thomas <Mark at> wrote:
> > As much as I love old CPUs, I've lost my patience with hard disk drives.
> > I've been using AztecMonster (search ebay) CF-SCSI adapters, with several-GB
> > CF cards instead of spinning disks. The KA660 and several PDP-11/83s
> > here run reliably from CF storage. I see now there are SCSI2SD cards for
> > half the price of the AztecMonster CF adapters I've been using. These
> > might be an alternative, if they play okay with whatever q-bus SCSI
> > controller you find. Installing from SCSI CDROM and using flash
> > storage is definitely the way to go if you can get the parts.
> That's great news to hear that the AztecMonster works on QBUS PDP-11s.
> I now know exactly what my future plans are...

I had mixed results with some QBUS SCSI adapters. Some played well
with the AztecMonster and some did not. Oddly, I think my Emulex UC07
was one that did not, but the CQDs and maybe one other model work fine.

> But I have a "random" question for those here. I know some of the QBUS
> (and UNIBUS) SCSI controllers can act both as an MSCP and TMSCP
> controller. (CMD CQD-220A/TM for one example.) And I know that several
> of the PDP-11 operating systems install from tape, and can install
> from TMSCP tape (hello RSTS/E). What I'd like to know is: Is there
> anything out there that can emulate a SCSI tape device on a CF card/SD
> card/USB stick/what-have-you?

So far, I've been using a DLT8000 when I've needed a sequential tape device, 
such as for the BSD2.11 install. It's been convenient to write the tape on
a Linux or Sun box, then plug it into the PDP11. All my older SCSI tape 
drives (Exabyte and DAT) have developed problems, but this DLT8000 drive 
works great.


Mark G. Thomas (Mark at, KC3DRE

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