> On Oct 18, 2023, at 10:20 AM, Henry Bent via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On Wed, 18 Oct 2023 at 10:16, Bill Gunshannon via cctalk <
> cctalk@classiccmp.org> wrote:
>
>>
>>
>> On 10/18/2023 10:00 AM, Henry Bent via cctalk wrote:
>>> On Wed, 18 Oct 2023 at 09:56, hupfadekroua via cctalk <
>> cctalk@classiccmp.org>
>>> wrote:
>>>
>>>> Hello all,
>>>>
>>>> does someone have a SCSI disc image of Ultrix 11 for a QBus based
>> (11/73)
>>>> PDP11.
>>>>
>>>
>>> Ultrix-11 doesn't support SCSI disks, as far as I am aware. What
>> hardware
>>> are you trying to use? In any case, you can easily use SIMH to install
>> 3.1
>>> (or your preferred version) and then transfer that to real hardware.
>>
>> PDP-11 SCSI Modules emulate MSCP and RA disks and work fine with
>> Ultrix-11.
>>
>
> Interesting. My Dilog DQ614 (ST506 emulating RL02s) specifically does not
> work with Ultrix, but does work with 2.xBSD and v7, so I would not
> necessarily assume that a third-party board was going to work with
> Ultrix-11's drivers.
There are two possible issues. One is that SCSI is a packet oriented storage
command/response system similar to MSCP but different. So the kind of
controllers Bill mentioned are essentiallly translators between the two
protocols.
If what you have is a native SCSI controller -- one that exposes the actual
SCSI commands -- then that requires an entirely different driver because that
isn't MSCP.
If you have an MSCP translator type controller, but the translation is poorly
done, you might end up with it failing for some operating systems. That's not
too unlikely given that the MSCP spec was for a long time a DEC confidential
document, so third parties had to reverse engineer things (and dodge DEC
lawyers).
paul
