SCSI ON A VAX 4000/500 - WHAT DO I NEED? - DEC

This is a discussion on SCSI ON A VAX 4000/500 - WHAT DO I NEED? - DEC ; Hi I have acquired a VAX 4000/500A - unfortunately it had no disks what-so-ever but I have managed to acquire a DSSI disk for it. I plan to run VMS 7.3 on this machine but don't particularly want to rely ...

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Thread: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

  1. SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    Hi

    I have acquired a VAX 4000/500A - unfortunately it had no disks
    what-so-ever but I have managed to acquire a DSSI disk for it.

    I plan to run VMS 7.3 on this machine but don't particularly want to
    rely on old, difficult to obtain DSSI disks - I would much rather run
    the box with SCSI disks.

    My trouble is trying to identify what my options are for converting the
    box to SCSI - I'm not a DEC/VAX hardware guru so codes like KXGYAFA-10
    (sorry being cheeky) don't mean a lot to me. From what I can find out
    there are two options some sort of QBUS card or a DSSI-SCSI convertor.
    I don't really fancy the QBUS card as I hear varying horror stories
    about that ranging from it's slower than a geological age, to "it only
    works with certain SCSI devices....and in any case not CDROMs or Disks"
    or it won't actually support booting.

    The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    assume it is some sort of box of tricks or electronic doo-ma-hicky that
    you plug a DSSI cable in and one side and magically it comes out as
    SCSI on the other side?

    If I type SHOW DEV or SHOW DSSI at the >>> prompt it does list two DSSI
    controllers/busses with IDs of 6 or 7 (which correspond to the little
    plugs on the front on the box). If I type SHOW SCSI it returns nothing,
    no errors, nothing (except the next >>> prompt).

    ANy help, details of Hardware conroller codes or designations that I
    need or descriptions of what these SCSI controllers are actually
    like...would be gratefully received.

    Regards


  2. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    Hi !

    On Wed, 29 Dec 2004 hairydamon@hotmail.com wrote:
    > I have acquired a VAX 4000/500A - unfortunately it had no disks
    > what-so-ever but I have managed to acquire a DSSI disk for it.


    4000/500A is BA400 series (floorstand of aour 100 pounds), isn't it?
    If it's a small desktop box, do you have some QBus backplane attached?

    > My trouble is trying to identify what my options are for converting the
    > box to SCSI - I'm not a DEC/VAX hardware guru so codes like KXGYAFA-10
    > (sorry being cheeky) don't mean a lot to me. From what I can find out
    > I don't really fancy the QBUS card as I hear varying horror stories


    Even if you don't like the module numbers... Hands off KZQSA. This is "SCSI",
    but it is just intended as tape controller. QBus SCSI controllers are a bit
    rare out there, i don't know if you want to use the box as commercial or as
    hobbyist, i assume the latter.

    Check eBay and look for QBUS MSCP SCSI adapters. The most of them come from
    Emulex i think, you can check vaxarchive.org for lots of module descriptions.
    The most important is that it speaks MSCP.

    > there are two options some sort of QBUS card or a DSSI-SCSI convertor.
    > about that ranging from it's slower than a geological age, to "it only
    > works with certain SCSI devices....and in any case not CDROMs or Disks"
    > or it won't actually support booting.


    As DSSI is too different from SCSI (AFAIK, DSSI talks some kind of MSCP), this
    really could be a problem. But you can run into this problem even with a QBus
    controller, it it's configured incorrectly. MSCP doesn't auto-detect the device
    types, so you have to configure them. I know this from my KFQSA (which is DSSI
    QBus).

    But there is nothing bad on QBus. Okay, it's slow. Maybe the onboard DSSI of
    the modern NVAX CPU of the 500A is faster. But do you really need more than
    about 3MB/s you get through QBus? Hey, it's a VAX. It's a workhorse, not made
    as a pure fileserver. And for this, your QBus SCSI is enough to feed the 10MBit
    ethernet

    > If I type SHOW DEV or SHOW DSSI at the >>> prompt it does list two DSSI
    > controllers/busses with IDs of 6 or 7 (which correspond to the little
    > plugs on the front on the box). If I type SHOW SCSI it returns nothing,
    > no errors, nothing (except the next >>> prompt).


    Yep. Why errors? You have nothing, so it just shows nothing. Otherwise, you
    would also see the controller there. But this "SCSI" might refer to the KZQSA,
    which might be okay as CD-ROM controller, but i think, VMS doesn't support hard
    disks on this.

    > ANy help, details of Hardware conroller codes or designations that I
    > need or descriptions of what these SCSI controllers are actually
    > like...would be gratefully received.


    Hope it helped a bit

    ....Michael

    --
    http://www.unixiron.org/ Home Powered by: (Net|Open|Free)BSD IRIX NonStop-UX
    Solaris AIX HP-UX Tru64 MUNIX Ultrix VMS SINIX Dolphin_Unix OpenStep MacOS A/UX

  3. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    hairydamon@hotmail.com wrote:
    > [snip]
    > The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    > assume it is some sort of box of tricks or electronic doo-ma-hicky that
    > you plug a DSSI cable in and one side and magically it comes out as
    > SCSI on the other side?


    Indeed. Search eBay for disk "shelves" such as BA350-xx (where "xx" can
    be any of a number of combinations). The HSD10 will occupy one location
    in teh shelf and will serve up disks on the shelf via DSSI. They will
    appear as DU devices.

    You'll still need some info. on how to configure the HSD10, but this
    should be one of many stepping stones on your way to what you seek...

    ....grasshopper. :-)

    --
    David J Dachtera
    dba DJE Systems
    http://www.djesys.com/

    Unofficial OpenVMS Hobbyist Support Page:
    http://www.djesys.com/vms/support/

    Unofficial Affordable OpenVMS Home Page:
    http://www.djesys.com/vms/soho/

    Unofficial OpenVMS-IA32 Home Page:
    http://www.djesys.com/vms/ia32/

  4. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    David J Dachtera wrote:

    > hairydamon@hotmail.com wrote:
    >> [snip]
    >> The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    >> assume it is some sort of box of tricks or electronic doo-ma-hicky that
    >> you plug a DSSI cable in and one side and magically it comes out as
    >> SCSI on the other side?

    >
    > Indeed. Search eBay for disk "shelves" such as BA350-xx (where "xx" can
    > be any of a number of combinations). The HSD10 will occupy one location
    > in teh shelf and will serve up disks on the shelf via DSSI. They will
    > appear as DU devices.
    >
    > You'll still need some info. on how to configure the HSD10, but this
    > should be one of many stepping stones on your way to what you seek...

    Or you might want to wait till my MSCP SCSI controller is ready. I am adding
    CDROM support at this point. Yes, My MSCP SCSI controller configures SCSI
    HD automatically. It supports SCSI disk from 5MB to 2GB at this point, and
    will support up to ... infinity (virtually) in the near future. Whatever
    SimH pdp11_rq.c does, The controller can do.

    vax, 9000

    >
    > ...grasshopper. :-)
    >



  5. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?



    On Wed, 29 Dec 2004 hairydamon@hotmail.com wrote:

    > The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    > assume it is some sort of box of tricks or electronic doo-ma-hicky that
    > you plug a DSSI cable in and one side and magically it comes out as
    > SCSI on the other side?


    I just picked up a Winchester systems DSSI tape unit on epay for $9. I
    contains a CMD CDI-4000 DSSI -> SCSI unit in it which doesn't much care if
    disks or tapes are plugged into it. I have a CDROM on it at the moment.

    Device SID Vendor Model Rev Dev Stat Maint Oper Maint Status
    ------- --- ------- ------- ---- --------- ---------- --------------------
    DIA300 0-0 TOSHIBA CD-ROM 3605 AVAILABLE


    ---
    Lord, protect me from those to whom you speak directly
    Leave the no-spam in, correct email address

  6. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?


    > Yep. Why errors? You have nothing, so it just shows nothing.

    Otherwise, you
    > would also see the controller there. But this "SCSI" might refer to

    the KZQSA,
    > which might be okay as CD-ROM controller, but i think, VMS doesn't

    support hard
    > disks on this.
    >


    KZQSA definately works as a CD-ROM controller... I've used it to boot a
    VAX 4000-400 back before I sold the whole lot off. Supported or not, I
    don't see why you couldn't boot a hard disk from the card unless the
    hardware/software specifically prevents it. (but I never tried
    that...)

    -Ben


  7. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    Hi !

    On Thu, 29 Dec 2004, Ben wrote:
    > KZQSA definately works as a CD-ROM controller... I've used it to boot a
    > VAX 4000-400 back before I sold the whole lot off. Supported or not, I
    > don't see why you couldn't boot a hard disk from the card unless the
    > hardware/software specifically prevents it. (but I never tried
    > that...)


    Sure, CD-ROM and TK50Z and stuff works. It's made for this and supported by the
    firmware. It even might be the firmware has no limitations in this place and
    can boot from hard disks here. But VMS doesn't support this controller as a
    hard disk controller. Pure political stuff. It has "just" 128KB buffer, and is
    not so intelligent like MSCP adapters, that's the reason why DEC sold this just
    as an interface for CD-ROMs and tapes. I didn't get any information about this
    thing, otherwise i would have written a driver for NetBSD for it But in my
    research i heard about the very bad implementation of this board. IIRC, it was
    something with the SCSI bus itself, no so much the controller logic.

    Technically, this board might even be better than a simple 5390 based SCSI
    controller like in VAXstation 3100s, but for a "real" VAX, this board just
    wasn't intended to be a true storage interface.

    Politically, it's comparable to the onboard SCSI in the VAXstation 2000. You
    could boot off TK50Z very fine. But you never saw some hard disk connected to
    this controller. After applying a nice patch to the firmware (can be found
    somewhere in the net), you could boot off NetBSD very well from SCSI disks on
    this controller. But nevertheless, VMS might not support it as controller for
    hard disks.

    It's not just a matter of booting... The OS also has something to tell

    ....Michael

    --
    http://www.unixiron.org/ Home Powered by: (Net|Open|Free)BSD IRIX NonStop-UX
    Solaris AIX HP-UX Tru64 MUNIX Ultrix VMS SINIX Dolphin_Unix OpenStep MacOS A/UX

  8. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    David J Dachtera writes:

    > hairydamon@hotmail.com wrote:


    >> The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    >> assume it is some sort of box of tricks or electronic doo-ma-hicky
    >> that you plug a DSSI cable in and one side and magically it comes
    >> out as SCSI on the other side?


    > Indeed. Search eBay for disk "shelves" such as BA350-xx (where "xx"
    > can be any of a number of combinations). The HSD10 will occupy one
    > location in teh shelf and will serve up disks on the shelf via
    > DSSI. They will appear as DU devices.


    > You'll still need some info. on how to configure the HSD10, but this
    > should be one of many stepping stones on your way to what you
    > seek...


    A HSD is the better way to go IMO. The 10 is pretty straight foward to
    set up, via a set host/dup, or by pluging a VT into the terminal port
    on it. Can do tapes as well. You may even be able to score a 40 or
    50 with drives. Freight is often the killer for them!

    --
    Paul Repacholi 1 Crescent Rd.,
    +61 (08) 9257-1001 Kalamunda.
    West Australia 6076
    comp.os.vms,- The Older, Grumpier Slashdot
    Raw, Cooked or Well-done, it's all half baked.
    EPIC, The Architecture of the future, always has been, always will be.

  9. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    Hi

    Thanks to everyone for answering so promptly - really appreciate that.

    In response to Michael Kukat's question the machine is the "desk-side"
    unit and (once I have disks installed!) intend to run OpenVMS 7.3
    hobbyist license. There's no additional boxes or QBUS doo-dahs attached
    to it's just what-ever is in the case. It does seem to have two
    M3119-YA although I have no plans to connect any additional async
    devices.

    >From everything else sounds like the best bet is a HSD-xx so I'll start

    looking although I'm intrigued by David's MSCP Scsi controller - are
    there any details anywhere?
    Once again thanks to everyone - no doubt I'll need a lot of guidance.


  10. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    [followups set to comp.os.vms]
    Michael Kukat wrote:
    >
    > Sure, CD-ROM and TK50Z and stuff works. It's made for this and supported by the
    > firmware. It even might be the firmware has no limitations in this place and
    > can boot from hard disks here. But VMS doesn't support this controller as a
    > hard disk controller. Pure political stuff. It has "just" 128KB buffer, and is
    > not so intelligent like MSCP adapters, that's the reason why DEC sold this just
    > as an interface for CD-ROMs and tapes. I didn't get any information about this
    > thing, otherwise i would have written a driver for NetBSD for it But in my
    > research i heard about the very bad implementation of this board. IIRC, it was
    > something with the SCSI bus itself, no so much the controller logic.


    As the KZQSA is an "ancient" adapter, I do not know the exact reasons
    that support is limited to CD-ROMs and Tapes.

    It may be that it was never tested on magnetic disks, or that one of the
    tests with then supported magnetic disks failed, and there was no way to
    make it work.

    Tapes and CD-ROMS at the time that the KZQSA was produced could not
    operate at the data rate of a magnetic disk, and that might allow them
    to work reliably, where a magnetic disk might fail a test at high loading.

    The tests that Digital/Compaq/HP does for devices intended for OpenVMS
    support are by design intended to be worse than anything that a end user
    would likely try. Some of them involve fault injection into the
    hardware to verify that no driver undetectable data corruption will occur.

    There is nothing in the driver for the KZQSA that prevents using it for
    magnetic disks, even though it is not supported.

    -John
    wb8tyw@qsl.network
    Personal Opinion Only


  11. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    hairydamon@hotmail.com wrote:

    > Hi
    >
    > Thanks to everyone for answering so promptly - really appreciate that.
    >
    > In response to Michael Kukat's question the machine is the "desk-side"
    > unit and (once I have disks installed!) intend to run OpenVMS 7.3
    > hobbyist license. There's no additional boxes or QBUS doo-dahs attached
    > to it's just what-ever is in the case. It does seem to have two
    > M3119-YA although I have no plans to connect any additional async
    > devices.
    >
    >>From everything else sounds like the best bet is a HSD-xx so I'll start

    > looking although I'm intrigued by David's MSCP Scsi controller - are
    > there any details anywhere?

    The webpage is at http://www.geocities.com/mscpscsi/
    There are many loose ends that need to be fixed.

    vax, 9000

    > Once again thanks to everyone - no doubt I'll need a lot of guidance.



  12. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    you are best off buying an old emulex ctr that emulates, hmmm, something too
    old for me to remember

    The one you need for the S Box (BA213) is the UC08-III - It has the funky
    handle with the two levers for the 4500
    You can find them from several dealers - try keyways.com - ask for mitch
    miller - he is an ex deccy and knows his stuff!

    we don't sell them any more !

    david

    --
    Island Computers US Corp
    2700 Gregory St Suite 180
    Savannah GA 31404
    Tel: 912 4476622
    Fax: 912 201 0402
    Email: dbturner@icusc.com


    wrote in message
    news:1104347519.289666.74980@f14g2000cwb.googlegro ups.com...
    > Hi
    >
    > I have acquired a VAX 4000/500A - unfortunately it had no disks
    > what-so-ever but I have managed to acquire a DSSI disk for it.
    >
    > I plan to run VMS 7.3 on this machine but don't particularly want to
    > rely on old, difficult to obtain DSSI disks - I would much rather run
    > the box with SCSI disks.
    >
    > My trouble is trying to identify what my options are for converting the
    > box to SCSI - I'm not a DEC/VAX hardware guru so codes like KXGYAFA-10
    > (sorry being cheeky) don't mean a lot to me. From what I can find out
    > there are two options some sort of QBUS card or a DSSI-SCSI convertor.
    > I don't really fancy the QBUS card as I hear varying horror stories
    > about that ranging from it's slower than a geological age, to "it only
    > works with certain SCSI devices....and in any case not CDROMs or Disks"
    > or it won't actually support booting.
    >
    > The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    > assume it is some sort of box of tricks or electronic doo-ma-hicky that
    > you plug a DSSI cable in and one side and magically it comes out as
    > SCSI on the other side?
    >
    > If I type SHOW DEV or SHOW DSSI at the >>> prompt it does list two DSSI
    > controllers/busses with IDs of 6 or 7 (which correspond to the little
    > plugs on the front on the box). If I type SHOW SCSI it returns nothing,
    > no errors, nothing (except the next >>> prompt).
    >
    > ANy help, details of Hardware conroller codes or designations that I
    > need or descriptions of what these SCSI controllers are actually
    > like...would be gratefully received.
    >
    > Regards
    >




  13. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    other ctrs (scsi q-bus)

    Emulex UC07 (-III)
    CMD CQD220 and 223 -T/M (Tape and Disk)
    Dilog DQ132

    I know these all work as my last job was running a company that was a
    reseller for all of these installing into
    4200/4300/4400/4500/4700 vaxen.
    By today's standards their capabilities are probably limited to v small scsi
    disks.

    Hope this helps

    --
    Island Computers US Corp
    2700 Gregory St Suite 180
    Savannah GA 31404
    Tel: 912 4476622
    Fax: 912 201 0402
    Email: dbturner@icusc.com


    wrote in message
    news:1104347519.289666.74980@f14g2000cwb.googlegro ups.com...
    > Hi
    >
    > I have acquired a VAX 4000/500A - unfortunately it had no disks
    > what-so-ever but I have managed to acquire a DSSI disk for it.
    >
    > I plan to run VMS 7.3 on this machine but don't particularly want to
    > rely on old, difficult to obtain DSSI disks - I would much rather run
    > the box with SCSI disks.
    >
    > My trouble is trying to identify what my options are for converting the
    > box to SCSI - I'm not a DEC/VAX hardware guru so codes like KXGYAFA-10
    > (sorry being cheeky) don't mean a lot to me. From what I can find out
    > there are two options some sort of QBUS card or a DSSI-SCSI convertor.
    > I don't really fancy the QBUS card as I hear varying horror stories
    > about that ranging from it's slower than a geological age, to "it only
    > works with certain SCSI devices....and in any case not CDROMs or Disks"
    > or it won't actually support booting.
    >
    > The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    > assume it is some sort of box of tricks or electronic doo-ma-hicky that
    > you plug a DSSI cable in and one side and magically it comes out as
    > SCSI on the other side?
    >
    > If I type SHOW DEV or SHOW DSSI at the >>> prompt it does list two DSSI
    > controllers/busses with IDs of 6 or 7 (which correspond to the little
    > plugs on the front on the box). If I type SHOW SCSI it returns nothing,
    > no errors, nothing (except the next >>> prompt).
    >
    > ANy help, details of Hardware conroller codes or designations that I
    > need or descriptions of what these SCSI controllers are actually
    > like...would be gratefully received.
    >
    > Regards
    >




  14. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    just did a dealer lookup for uc08
    you'll be l;ooking at $400-500 from any of the dealers out there.
    If you want the list of names for these let me know

    dt

    --
    Island Computers US Corp
    2700 Gregory St Suite 180
    Savannah GA 31404
    Tel: 912 4476622
    Fax: 912 201 0402
    Email: dbturner@icusc.com


    "DAVID TURNER" wrote in message
    news:10taqqa33br6be9@news.supernews.com...
    > you are best off buying an old emulex ctr that emulates, hmmm, something

    too
    > old for me to remember
    >
    > The one you need for the S Box (BA213) is the UC08-III - It has the funky
    > handle with the two levers for the 4500
    > You can find them from several dealers - try keyways.com - ask for mitch
    > miller - he is an ex deccy and knows his stuff!
    >
    > we don't sell them any more !
    >
    > david
    >
    > --
    > Island Computers US Corp
    > 2700 Gregory St Suite 180
    > Savannah GA 31404
    > Tel: 912 4476622
    > Fax: 912 201 0402
    > Email: dbturner@icusc.com
    >
    >
    > wrote in message
    > news:1104347519.289666.74980@f14g2000cwb.googlegro ups.com...
    > > Hi
    > >
    > > I have acquired a VAX 4000/500A - unfortunately it had no disks
    > > what-so-ever but I have managed to acquire a DSSI disk for it.
    > >
    > > I plan to run VMS 7.3 on this machine but don't particularly want to
    > > rely on old, difficult to obtain DSSI disks - I would much rather run
    > > the box with SCSI disks.
    > >
    > > My trouble is trying to identify what my options are for converting the
    > > box to SCSI - I'm not a DEC/VAX hardware guru so codes like KXGYAFA-10
    > > (sorry being cheeky) don't mean a lot to me. From what I can find out
    > > there are two options some sort of QBUS card or a DSSI-SCSI convertor.
    > > I don't really fancy the QBUS card as I hear varying horror stories
    > > about that ranging from it's slower than a geological age, to "it only
    > > works with certain SCSI devices....and in any case not CDROMs or Disks"
    > > or it won't actually support booting.
    > >
    > > The DSSI-SCSI convertor (HSD10?) option sounds like the best bet. I
    > > assume it is some sort of box of tricks or electronic doo-ma-hicky that
    > > you plug a DSSI cable in and one side and magically it comes out as
    > > SCSI on the other side?
    > >
    > > If I type SHOW DEV or SHOW DSSI at the >>> prompt it does list two DSSI
    > > controllers/busses with IDs of 6 or 7 (which correspond to the little
    > > plugs on the front on the box). If I type SHOW SCSI it returns nothing,
    > > no errors, nothing (except the next >>> prompt).
    > >
    > > ANy help, details of Hardware conroller codes or designations that I
    > > need or descriptions of what these SCSI controllers are actually
    > > like...would be gratefully received.
    > >
    > > Regards
    > >

    >
    >




  15. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    In article , "John E. Malmberg" writes:
    :[followups set to comp.os.vms]
    :Michael Kukat wrote:
    :>
    :> Sure, CD-ROM and TK50Z and stuff works. It's made for this and supported by the
    :> firmware. It even might be the firmware has no limitations in this place and
    :> can boot from hard disks here. But VMS doesn't support this controller as a
    :> hard disk controller. Pure political stuff. It has "just" 128KB buffer, and is
    :> not so intelligent like MSCP adapters, that's the reason why DEC sold this just
    :> as an interface for CD-ROMs and tapes. I didn't get any information about this
    :> thing, otherwise i would have written a driver for NetBSD for it But in my
    :> research i heard about the very bad implementation of this board. IIRC, it was
    :> something with the SCSI bus itself, no so much the controller logic.
    :
    :As the KZQSA is an "ancient" adapter, I do not know the exact reasons
    :that support is limited to CD-ROMs and Tapes.
    :
    :It may be that it was never tested on magnetic disks, or that one of the
    :tests with then supported magnetic disks failed, and there was no way to
    :make it work.


    The KZQSA isn't expected to operate reliably with SCSI configuratious
    outside those that were explicitly supported. Sometimes it worked,
    and sometimes it didn't.

    We traditionally don't usually describe why we don't support a particular
    unsupported configuration, nor specifically detailing what was wrong
    (if we tested it), as that can obviously approach a support statement.
    We can also obviously choose not to support a configuration for other
    reasons -- though in this particular case, the reason was technical.

    While Michael Kukat has apparently had this configuration work within
    those configuration(s) tested, I've had the KZQSA lock up on me. (For
    better or worse, all ancient SCSI configurations are somewhat unstable.)

    The HSD05 or similar is the usual and official solution for SCSI on a
    Q-bus configuration, and there are (or once were) various third-party
    SCSI Q-bus controllers available. The series of MicroVAX referenced
    does have DSSI, so DSSI to SCSI adapters are available.

    An alternative fix is to find and replace the VAX 4000 series system
    with a MicroVAX or VAXstation series system with native SCSI -- this
    might be easier, and it might even be cheaper. (This assumes that the
    Q-bus is not being used for an "unusual" Q-bus adapter, of course.)

    ---------------------------- #include -----------------------------
    For additional, please see the OpenVMS FAQ -- www.hp.com/go/openvms/faq
    --------------------------- pure personal opinion ---------------------------
    Hoff (Stephen) Hoffman OpenVMS Engineering hoff[at]hp.com


  16. Re: SCSI ON A VAX 4000/500 - WHAT DO I NEED?

    "Hoff Hoffman" wrote in message
    news:PrDCd.5069$5o6.1376@news.cpqcorp.net...
    > In article , "John E. Malmberg"
    > writes:
    > :[followups set to comp.os.vms]
    > :Michael Kukat wrote:
    > :>
    > :> Sure, CD-ROM and TK50Z and stuff works. It's made for this and
    > supported by the
    > :> firmware. It even might be the firmware has no limitations in this
    > place and
    > :> can boot from hard disks here. But VMS doesn't support this controller
    > as a
    > :> hard disk controller. Pure political stuff. It has "just" 128KB buffer,
    > and is
    > :> not so intelligent like MSCP adapters, that's the reason why DEC sold
    > this just
    > :> as an interface for CD-ROMs and tapes. I didn't get any information
    > about this
    > :> thing, otherwise i would have written a driver for NetBSD for it But
    > in my
    > :> research i heard about the very bad implementation of this board. IIRC,
    > it was
    > :> something with the SCSI bus itself, no so much the controller logic.
    > :
    > :As the KZQSA is an "ancient" adapter, I do not know the exact reasons
    > :that support is limited to CD-ROMs and Tapes.


    Sorry to so late on this subject....

    I once did some testing on this controller and although disks 'did' work,
    you'd hardly ever want to use them connected here.

    The reason being the above mentioned 128K byte buffer. This was a buffer on
    the board which appeared in Qbus memory space. The host CPU was responsible
    for all data transfers to/from this buffer (i.e. there was NO DMA, so the
    host CPU was the DMA engine). This was even worse than you might think (how
    could that be) since memory acess cycles to Qbus memory were DRAMATICALLY
    slower than normal memory accesses, the CPU was really sucked away. This
    probably ended up making disk data transfers significantly more expensive
    than console floppy access was on an 780. More expensive is relative since
    the 780 was up to the task, but the 4000/500 was many times faster than the
    780, but it was also just "up to the task" of performing these slow data
    transfers, no CPU left for much of anything else if the application disk I/O
    load was even slightly interesting.

    - Mark Pizzolato



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