5 Dec
2017
5 Dec
'17
10:16 a.m.
I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card
(M5976). If the card did not have the large metal face, would it work in
a Q-bus PDP-11? We are not going to potentially ruin a card by trying
this, but I am interested to know if this is the case.
Thanks,
Aaron.
6 Dec
6 Dec
4:33 p.m.
An M5976 KZQSA is not MSCP compatible so it wouldn't do any good with a
PDP-11 system. It's really only useful for RRD4x SCSI CD-ROM drives with
VMS on a VAX 4000.
On Dec 6, 2017 9:47 AM, "Aaron Jackson via cctech" <cctech at
classiccmp.org>
wrote:
I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card
(M5976). If the card did not have the large metal face, would it work in
a Q-bus PDP-11? We are not going to potentially ruin a card by trying
this, but I am interested to know if this is the case.
Thanks,
Aaron.
4:43 p.m.
Thanks Glen and Jerry.
I think that settled that debate! haha
Thanks,
Aaron.
Glen Slick writes:
An M5976 KZQSA is not MSCP compatible so it
wouldn't do any good with a
PDP-11 system. It's really only useful for RRD4x SCSI CD-ROM drives with
VMS on a VAX 4000.
On Dec 6, 2017 9:47 AM, "Aaron Jackson via cctech" <cctech at
classiccmp.org>
wrote:
I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card
(M5976). If the card did not have the large metal face, would it work in
a Q-bus PDP-11? We are not going to potentially ruin a card by trying
this, but I am interested to know if this is the case.
Thanks,
Aaron.
--
Aaron Jackson
PhD Student, Computer Vision Laboratory, Uni of Nottingham
http://aaronsplace.co.uk
7 Dec
7 Dec
11:50 a.m.
On 12/06/2017 03:43 PM, Aaron Jackson via cctalk wrote:
Thanks Glen and Jerry.
I think that settled that debate! haha
Thanks,
Aaron.
Glen Slick writes:
> An M5976 KZQSA is not MSCP compatible so it wouldn't do any good with a
> PDP-11 system. It's really only useful for RRD4x SCSI CD-ROM drives with
> VMS on a VAX 4000.
>
>
MSCP is a software protocol. Any device that has a driver
available for the PDP-11 operating system you want to use
can use that device. Most of the really old disk and tape
interfaces were NOT MSCP compatible. We also hacked up some
oddball drivers to use old PDP-11-type devices on VAXes.
But, yes, if there's no driver to support the interface,
then it doesn't really matter if the device is electrically
compatible.
Jon
12:44 p.m.
On Dec 7, 2017, at 11:50 AM, Jon Elson via cctalk
<cctalk at classiccmp.org> wrote:
...
MSCP is a software protocol. Any device that has a driver available for the PDP-11
operating system you want to use can use that device.
True with small variations. A sufficiently large disk might not be supported on some OS
because the on-disk structure is limited in what device size it can handle. (This applies
to RSTS for example.) Some devices use obscure MSCP mechanisms that might not be in all
drivers -- for example, the RA80 uses host-based bad block replacement, which is quite a
complicated process; I know RSTS supports that but it might be omitted in some other
operating systems.
Also, in DEC terminology, "supported" doesn't mean "it works in the
software" but rather "we stand behind it". That means tested, sold,
handled by product support and field service, etc. For example, the RP07 works in RSTS on
an 11/70, but it is not "supported". I'd expect the same is true for any
number of MSCP or TMSCP devices that were intended to be sold only on VAXen -- they may
very well work, but if you had plugged one in on a machine where they aren't
supported, DEC would give you no help with any problems.
paul
2:22 p.m.
On 12/07/2017 12:44 PM, Paul Koning via cctalk wrote:
MSCP is
supported by most for the common PDP-11 OSs.? Only the older
UNIX flavors lack a driver.
However it has the component of local intelligence in the controller and
if the controller supports
MSCP such as RQDX(1/2/3) it works with RDxx MFM disks, floppies both
5.25(RX50 and RX33)
and 3.5 (RX2x).? There are also the CMD and other controllers that are
MSCP but do SCSI disks,
Tapes and CDrom. ? So it a software protocol for communicating with
controllers that understand that.
The interface to the devices were on the "other" side of that.
As such PDP11 and VAX support is there unless the OS in non-DEC in
origin and even then if the
time frame made it a marketing requirement the third party OS vendor had it.
An example is a RD54 on a Qbus PDP-11 running RT11.? You need the LD
driver to partition the
disk as RT supports only 32mb or smaller devices and the RD54 is 150.??
It was supported but
not ever sold that way.
Things like block replacement are options of the OS and the device IO is
then just a
interface.? The protocol for to talk to the device is a lower level
layer in most cases.
On Dec 7, 2017, at 11:50 AM, Jon Elson via cctalk
<cctalk at classiccmp.org> wrote:
...
MSCP is a software protocol. Any device that has a driver available for the PDP-11
operating system you want to use can use that device.
True with small variations.
A sufficiently large disk might not be supported on some OS because the on-disk structure
is limited in what device size it can handle. (This applies to RSTS for example.) Some
devices use obscure MSCP mechanisms that might not be in all drivers -- for example, the
RA80 uses host-based bad block replacement, which is quite a complicated process; I know
RSTS supports that but it might be omitted in some other operating systems. Also, in DEC terminology, "supported"
doesn't mean "it works in the software" but rather "we stand behind
it". That means tested, sold, handled by product support and field service, etc.
For example, the RP07 works in RSTS on an 11/70, but it is not "supported".
I'd expect the same is true for any number of MSCP or TMSCP devices that were intended
to be sold only on VAXen -- they may very well work, but if you had plugged one in on a
machine where they aren't supported, DEC would give you no help with any problems.
Usually true.? If you were an important enough customer they did.? More
often that that it was not a
device level thing it was a system level "supported configuration" and
help might be had, depending
on the field office.
paul
3:09 p.m.
On Dec 7, 2017, at 2:22 PM, allison via cctalk
<cctalk at classiccmp.org> wrote:
On 12/07/2017 12:44 PM, Paul Koning via cctalk wrote:
...
Things like block replacement are options of the OS and the device IO is
then just a
interface. The protocol for to talk to the device is a lower level
layer in most cases.
No, bad block replacement in the UDA50/RA80 case is an MSCP mechanism where the controller
(UDA50) offloads the work of managing bad blocks in part to the OS. The host still sees a
logically contiguous error-free block space, just like in other MSCP devices (but unlike
pre-MSCP). But if a block is found to be bad, the host driver has to help out with the
process of assigning a replacement block. It's very different from the earlier bad
block management which simply involves marking the offending LBAs as unavailable in the
file system free space tables, and much more complicated. (The code in RSTS is about 2000
lines.)
paul
On Dec 7, 2017, at 11:50 AM, Jon Elson via cctalk
<cctalk at classiccmp.org> wrote:
...
MSCP is a software protocol. Any device that has a driver available for the PDP-11
operating system you want to use can use that device.
True with small variations.
A sufficiently large disk might not be supported on some OS because the on-disk structure
is limited in what device size it can handle. (This applies to RSTS for example.) Some
devices use obscure MSCP mechanisms that might not be in all drivers -- for example, the
RA80 uses host-based bad block replacement, which is quite a complicated process; I know
RSTS supports that but it might be omitted in some other operating systems. 
7:02 p.m.
On Dec 7, 2017, at 1:22 PM, allison via cctalk
<cctalk at classiccmp.org> wrote:
?..
As such PDP11 and VAX support is there unless the OS in non-DEC in
origin and even then if the
time frame made it a marketing requirement the third party OS vendor had it.
An example is a RD54 on a Qbus PDP-11 running RT11. You need the LD
driver to partition the
disk as RT supports only 32mb or smaller devices and the RD54 is 150.
It was supported but
not ever sold that way.
Things like block replacement are options of the OS and the device IO is
then just a
interface. The protocol for to talk to the device is a lower level
layer in most cases.
I think you are actually referring to the logical partitioning in the DU handler under
RT-11. The DU (MSCP) handler managed this and had the ability to allow
the disk to handle bad block replacement (RA type device) or do it in the controller
(RD).
The KZQSA is not listed as supported in V5.6. i have not seen documentation
on how it configured SCSI drive support. I would be interested to know if anyone tried
to use it under RT-11.
Jerry
6 Dec
6 Dec
4:36 p.m.
The metal face on the Q-Bus cards was there as part of the solution to meet FCC (or
equivalent) regulations to
reduce electrical interference to radio receivers and other devices.
If you can physically fit it into a older Qbus backplane and sort out the cabling it
should work
provided you have the necessary drivers.
However, I?m not aware of drivers for the M5976 for most PDP/LSI-11 operating systems.
Even for VMS or Ultrix
the card is reported to only support specific DEC hardware, even thought is SCSI
controller.
Jerry
On Dec 5, 2017, at 9:16 AM, Aaron Jackson via cctech
<cctech at classiccmp.org> wrote:
I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card
(M5976). If the card did not have the large metal face, would it work in
a Q-bus PDP-11? We are not going to potentially ruin a card by trying
this, but I am interested to know if this is the case.
Thanks,
Aaron.
2418
days inactive
2421
days old
8 comments
6 participants
participants (6)
-
aaron＠aaronsplace.co.uk -
allisonportable＠gmail.com -
elson＠pico-systems.com -
glen.slick＠gmail.com -
jsw＠ieee.org -
paulkoning＠comcast.net