Amiga ISO Collection/AmigaUtilCD1.iso/CDRom/ia-cdw.lha/extras/guru-rom/Guru-ROM_english

Text File | 1995-07-08 | 10.8 KB | 291 lines

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      omniscsi.device - GVP ROM module by Ralph Babel

A new device driver for all Series-II SCSI host adapters and
all turbo cards with a GVP SCSI host adapter.

Increasing requirements and a larger variety of available
SCSI devices made it necessary to rewrite the original GVP
device driver. In the previous driver versions, new program
portions would be added occasionally to solve problems that
existed with a few popular SCSI devices. Also, an
ever-increasing number of GVP products needed to be
supported in the driver.

In time, all of this resulted in considerable space
problems, which led to compromises in the development of the
driver, but it was nevertheless still possible to support
all of the current devices. Unfortunately, because of the
price war more and more manufacturers deviate from the SCSI
standard in their hardware and firmware or choose to save
money in certain areas. An example of this is certain CD-ROM
drives that no longer support PARITY.

The new OMNISCSI.DEVICE driver is a portable driver for all
Amigas and is first being made available for the most widely
used SCSI host adapter on the Amiga: the GVP Series-II. It
is faster and more reliable than all previous standard SCSI
device drivers, but nevertheless fully compatible to all
previously supported SCSI devices and then some.

With all of these extensions, however, the new device driver
no longer fits into the existing ROM area provided by the
Series-II. It was therefore combined with a ROM adapter that
allows up to four times as much address space as before to
be addressed.

- Which hardware is actually supported?

  - Series-II SCSI host adapters with and without RAM option
    for the A2000/A3000/A4000

  - Series-II SCSI host adapter for the A500

  - A530 turbo card for the A500

  - Combo030 turbo cards for the A2000

  - G-Force030 turbo cards for the A2000

  - G-Force040 turbo card for the A2000

  - A1208 SCSI host adapter for the A1200

- Will my system act exactly the same as before, after I
  install the ROM module?

  In essence, there is only a single incompatible change
  that can be noted in your system: the name of the device
  driver has changed. In the past, it would show up under
  the name GVPSCSI.DEVICE; now it is called OMNISCSI.DEVICE.

- Is there a new GVPPATCH to prevent modem problems while
  using DMA transfers?

  The patch no longer exists in its original form, but has
  instead been integrated into the control program
  GVPSCSICTRL. It is actually needed for high-speed
  transfers only.

- Do I get an even greater performance by using the B
  version of the SCSI chip 33C93?

  All known bugs in the internal processing of the 33C93 and
  the 33C93A are worked around by the device driver.
  Installing a 33C93B chip, which would be difficult in most
  cases anyway because of the use of SMD mounting on most
  GVP cards, is unnecessary.

  One argument often used in favor of using the B version is
  the support for FAST SCSI, but since the Zorro-II bus is
  already at capacity with a throughput of 3.5 Mbytes/s, the
  synchronous transfers of the A version of the 33C93 (max.
  4.7 Mbytes/s) is more than sufficient.

- I have previously had problems using BRU and AMAX IV. Can
  these be resolved?

  BRU and AMAX IV are among the most popular, although not
  the only programs within which problems occurred with the
  GVPSCSI.DEVICE. Because the driver adhered strictly to
  Commodore's "Direct SCSI" standard, it revealed bugs in a
  few incorrectly written programs. In both cases named
  above, for example, the problem lay with the fact that a
  particular flag (SCSIF_READ) was not being set, which is,
  however, required by the above-mentioned standard. The new
  OMNISCSI.DEVICE can be configured to work around such
  problems.

- I want to transfer data on my hard disks in synchronous
  mode. Is that possible?

  Previously, it was only possible to write the appropriate
  information into the RDB when a hard disk was prepped, but
  the mode was not really used. With the new driver, the use
  of SCSI devices in synchronous mode is finally possible.

- In the past, I always had to wait a long time for my
  machine to start. Is it faster now?

  The long delays are in part because of the SCSI protocol,
  but there are ways to achieve a nearly instantaneous boot
  of the computer from the system hard disk without
  violating the SCSI specification. This has been taken into
  consideration in the new driver.

- My A4000/040 doesn't support DMA to Chip RAM. Will that
  present a problem with the use of the host adapter?

  For this hardware problem of older revisions of the 68040
  card used in the A4000, the driver provides an option that
  prevents all DMA to Chip RAM, but which still permits
  access to the rest of the Zorro-II area - such as on-board
  RAM.

- Which SCSI peripherals are supported?

  All SCSI devices we had access to were tested - current
  and also some from our "museum" - including a number of
  cartridge drives, CD-ROM drives, and streamers. In spite
  of exhaustive testing, no problems were noted.

- Shouldn't a good SCSI driver support all SCSI devices
  automatically?

  Actually yes, but this isn't always "automatically"
  possible. Each SCSI device includes its own SCSI
  controller with its own firmware. It would be nice if
  these were always free of bugs, but that is unfortunately
  not always the case. This means that - if a problem can't
  be resolved by switching off certain driver options -
  sometimes the problem must be programmed around. This, of
  course, is only then possible when the problem is known,
  and is one of the reasons why from time to time new
  revisions of the GVPSCSI.DEVICE were released. All
  previously noted SCSI device firmware bugs have been taken
  into consideration in the new driver.

- What other improvements does the new driver offer me?

  - Data transfers have no restrictions, so that the optimum
    values for the MOUNTLIST/RDB entries MASK, MAXTRANSFER,
    and BUFMEMTYPE can be used. The driver itself decides
    what the most efficient way for transferring data is
    (DMA, buffered DMA, or PIO) and requires no workarounds
    in the filesystem that would slow down transfers.

  - Transfer mode and SCSI options like DISCONNECT,
    SYNCHRONOUS, and PARITY can be configured individually
    for each board or connected SCSI device, respectively.
    This results in a much more comfortable configuration of
    your system.

  - The rescan command is now required only if a hard disk
    partition (e.g. on a removable medium) must be mounted
    after boot-up.

  - An interesting new function makes it possible to
    completely write-protect a medium, which blocks even
    those commands that bypass the filesystem and talk
    directly to the driver (HD_SCSICMD, CMD_WRITE,
    TD_FORMAT). In this way for instance, the system drive
    can be protected from any type of virus.

  - The I/O Extender integrated in the G-Force040 is now
    usable even if no SCSI drive is connected.

- Which data transfer rates are possible on my system?

  Due to the multitude of possible GVP host adapters and the
  virtually unlimited variety of SCSI devices and the
  resulting combinations it is difficult to provide general
  benchmarks for all situations. As an example, we have
  selected a configuration that provides a typical
  environment:

  - A2000B revision 4.1 (PAL; the NTSC version is faster)
    WITHOUT accelerator card or other accelerating
    components

  - Kickstart 37.175, Workbench 37.67

  - 1 MB Chip RAM

  - GVP Series-II SCSI host adapter populated with 2 MB of
    Fast RAM

  - Maxtor MXT 540 hard disk

  There are three fundamentally different types of transfer
  rates, all of which are used in reviews and advertising:

  - Raw data transfer speed

    The maximum data transfer rate of the host adapter is
    limited by the Zorro-II bus only and can be as high as
    3.5 Mbytes/s. The program RAWSCSISPEED measures the
    values for READ BUFFER and WRITE BUFFER and provides a
    good approximation of that particular maximum transfer
    rate. In the test system, values of approximately 3.4
    Mbytes/s were measured for both reading and writing.

  - Transfer rate at the device-driver level

    This transfer speed can be measured with the program
    SCSISPEED (FF665). Unlike with RAWSCSISPEED, here the
    time required for the interpretation of the commands,
    among other things, _is_ taken into account. For a
    256-Kbyte buffer, a value of 3.1 Mbytes/s was measured.
    It dropped to 2.6 Mbytes/s when SCSISPEED also evaluated
    the amount of available CPU time. This was reported as
    79%; thus according to the results of SCSISPEED, the
    load on the CPU from the driver is only 21%.

  - Transfer rate at the filesystem level

    Using the program DISKSPEED (also on FF665), the data
    transfer rate can be measured at the DOS level. The
    resulting values are strongly dependent on the
    filesystem used, the block size, the buffers,
    fragmentation of the hard disk, and other factors, so
    that here only limited conclusions can be drawn about
    the speed of the host adapter and its device driver. In
    spite of that, measurements were made. On an empty
    partition that was placed on the outer tracks of the
    hard disk (with a logical block size of 512 bytes),
    DISKSPEED showed a result of 2.4 Mbytes/s both during
    reads and writes of 256-Kbyte blocks in the above
    configuration.

  Once again as a reminder: all of the above values apply to
  a pure 68000-based system in a minimal configuration.

- And what about SCSI-2?

  The new driver completely conforms to SCSI-2. Existing GVP
  SCSI host adapters, however, do not provide terminator
  power (TERMPWR), which is optional in SCSI-1 only. All of
  the differences between SCSI-1, CCS, and SCSI-2 are
  handled transparently by the driver though, and do not
  affect normal operation. The SCSI bus itself remains 8
  bits wide, of course, and doesn't support FAST or WIDE
  transfers, two of the new options under SCSI-2, but the
  new OMNISCSI.DEVICE pushes the Zorro-II bus to its limits
  anyway. Because of that, the use of SCSI-2 devices in
  general poses no problem.


Price: DEM 99.00

Shipping & Handling: DEM 15.00

All major credit cards are accepted.


Stefan Ossowski's Schatztruhe
Gesellschaft fuer Software mbH
Veronikastrasse 33
D-45131 Essen
Germany
Voice: [phone]
Fax:   [phone]
E-Mail: <[e-mail]>

Amiga Library Services
610 North Alma School Road, Suite 18
Chandler, AZ 85224-3687
USA
Fax or voice: [phone]
Voice only:   [phone]
E-Mail: <[e-mail]>


Copyright (C) 1994, 1995 Ralph Babel. All right reserved.