Copyright: Copyright 1995.  Western Digital Corporation.
Citation: Copyright 1995  Western Digital Corporation. All Rights Reserved


Contents

High Performance PCI To SCSI 2 Host Adapters

Click on the icon or topic you want to learn about.

About Western Digital SCSI 2 Host Adapters

Troubleshooting Western Digital PCI to SCSI Host Adapters

SCSI School (A glossary of SCSI terms)

About Western Digital

Technical Support

Version Information


About the 7196 Host Adapter
About The Western Digital SCSI Host Adapter

To learn more about your host adapter, click on any item in the picture.

Note: This is a photo of the high end host adapter in Western DigitalsPCI-SCSI line . If you own a 7193 or 7197 it will be similar to the photograph below.

The WD  PCI-SCSI 2 Host adapter connects a SCSI 2 Bus to your host systems PCI Bus.

Data can be transfered over the SCSI 2 bus at speeds up to 20MB/s and over the PCI bus at over 132 MB/s. To take advantage of the PCI buses higher bandwidth you can plug more than one WD host adapter into your PCI bus slots. This allows you to connect more than 15 SCSI devices to your PCI bus sytem.

A 128 byte PCI FIFO and a 32 byte SCSI FIFO speed data from the PCI bus to the SCSI bus and back.


Troubleshoot

Troubleshooting your SCSI 2 host adapter

(Click on the question to get an answer)

Q: Sometimes my host adapter doesn't transfer data reliably. What should I do?

Q: I just added a new device to my SCSI bus and now it doesn't work.

Q: I want to attach an 8 bit SCSI device to my Western Digital 16 bit Host Adapter. How do I do it?

Q: I just added a Fast & Wide SCSI device but it doesn't perform as well as I had hoped.

Q: My system locks up while booting and trying to load WD296.EXE.  Why?

Q: I am only able to use the compatablity mode driver with my host adapter, there's no "built-in" driver with Win95 release 490. What driver should I use?

Q: When I plug in my new host adapter it hangs up my system/ It doesn’t work. What could possibly be wrong?


 SCSI SCHOOL

TERMS

Active Termination

ASPI

ASPI device driver

ASPI Manager

Bandwidth

BIOS

BIST

Bus Master

CPU

Device Driver

Differential SCSI

Disk Array

EIDE

Fast SCSI

Host Bus Adapter

Host Computer

I/O

Initiator

Interrupt

Interrupt overhead

Logical Unit Number

LUN

MIPS

Multi Threaded

Parity

Passive Termination

PCI

Peripheral

PowerPC

Protocol

RAID

RAM

RISC

Rom

Scatter/Gather

SCSI

SCSI 2

SCSI Cable

SCSI ID

Single Ended

Single Threaded

Synchronous Transmission

Target

Task

Terminator

Thread

WCS

Wide SCSI


Active Termination

SCSI signals are terminated by a circuit. resulting in more reliable data transfer because there is less electrical noise.


ASPI

ASPI is an acronym for Advanced SCSI Programming Interface

It is a protocol to allow a SCSI host adapter and a SCSI device such as a disk drive to communicate.

ASPI makes the connecting of SCSI devices to a computer system much simpler. It consists of two or more parts,

An ASPI Manager which is a device driver that manages one or more host adapters and ASPI device drivers which manage SCSI devices such as disks, cd-roms and SCSI tapes.


ASPI Manager

The ASPI manager is a device driver associated with a particular host adaper such as the Western Digital PCI-SCSI host adapter.The manager handles I/O requests from SCSI devices with ASPI device drivers via the ASPI protocol.


ASPI Device Driver

An ASPI device driver operates a particular SCSI device and sends requests for that device to an ASPI Manager

A typical system with a SCSI cd-rom, disk and host adapter would load the following drivers:

1st loaded would be the ASPI manager for the host adpater,

then the ASPI device drivers for the cd-rom, disk and tape would load in any order.


Bandwidth

The amount of data that can be transferred on a bus in a given amount of time. The PCI local bus can transfer data at speeds up to 132MB/s That means at the end of 1 second 132 megabytes can be transfered  A wide fast SCSI-2 bus can transfer data at 20 MB/s.


BIOS

(Basic Input/Output System.) This is a chip that contains code to boot up your system. The Western Digital PCI - SCSI host adapter also has an expansion  BIOS on board to boot up the host adapter.


BIST

Built In Self Test a test conducted each time power is turned on. This ensures that your computer is working correctly before you use it.


Bus Master

A device that has the ability to take over the PCI bus and control the entire bus without intervention from the host CPU. Western Digital PCI-SCSI host adapters have the ability to become a bus master.


Corel SCSI

A software product from Corel Systems Corporation which supports many SCSI devices via the ASPI protocol.


CPU

(Central Processing Unit)  The chip which does all of the calculations needed to make a computer function. Western Digital PCI-SCSI host adapters have an auxilary RISC processor which frees the CPU from the tedious task of moving data from peripheral devices.


Device Driver

A special  program that allows an operating system to transfer data to and from a particular piece of hardware. A device driver is usually loaded at boot time. In the case of MS-DOS a device driver is loaded by using a "DEVICE=" line in the config.sys file.


Differential SCSI

Electrical signal configuration that uses a pair of lines to differentiate actual signals from noise. Each signal driver has two outputs and each receiver has two inputs. In comparison to single-ended configurations differential configurations have a larger  tolerance for noise and allow for longer cable length of up to 25 meters(19.68 feet), but are more expensive due to dual connector  pins, and additional devices on the adapter .


EIDE

Enhanced IDE or Enhanced Intelligent Drive Electronics. (IDE is also known as an AT interface) This is an interface limited to disk drives, tapes and cd-roms. It offers less performance than SCSI but is often less expensive.


Fast SCSI

Transfers data in a synchronous manner based on a common clock signal.  This doubles the data transfer speed compared to SCSI-1 or asynchrounous SCSI 2.  A Fast & Wide SCSI device such as the Western Digital PCI-SCSI host adapter can transfer data across the SCSI bus at 20MB/sec.


Host Bus Adapter

Circuitry that translates between a processor’s internal bus and a different bus, such as SCSI. The Western Digital PCI-SCSI host bus adapter connects an internal PCI local bus and a SCSI bus.


Host Computer

Computer in charge to which special purpose peripheral systems are attached.

It is said to be a host to peripheral devices.


I/O

Input/Output


Initiator

Unit responsible for starting some activity on the SCSI bus. Often a SCSI Host Bus Adapter. An initiator sends a request to a SCSI target  by using the targets SCSI id.


Interrupt

A signal to the CPU to stop what it is doing and give service to the device generating the interrupt.  The Western Digital PCI-SCSI host adapter interrupts the CPU much less often than other SCSI host adapters thus freeing the CPU to do other things such as run your application.


Interrupt overhead

The amount of time the CPU needs to service an interrupt request.


Logical Unit Number

(LUN)

A sub division of a SCSI target. A SCSI target can be subdivided to include up to eight Logical Units.


MIPS

Millions of Instructions Per Second. Refers to the number of instructions a processor can perform per second.


Multi Threaded

The ability of a SCSI device to accept several commands at once. See Task.


Parity

A method of checking the accuracy of transmitted data at the binary level of zero’s and ones, i.e. bits with  8 bits per byte (single character), an extra bit, called a parity bit, is added to the transmitted byte. If even parity is used, the sum of all bits is even. If odd parity is used the sum of all bits is odd.


Passive Termination

A method of terminating a SCSI bus using simple electronic components. This is a less expensive method than active termination but it is not as effective in reducing electrical noise on the SCSI bus.


PCI

Peripheral Component Interconnect or Interface. A high performance bus used to connect high bandwith peripherals such as video cards and Host Bus Adapters to a host computer.


Peripheral

Special purpose system external  to the host computer. Examples of peripherals include tape drives, CD-ROM drives, printers, and scanners.


Power PC

A RISC processor jointly developed by Motorola, IBM, and Apple.


Protocol

A method of establishing and maintaining communication  including initiation or request to transmit, destination and source identification, request acknowledgment, data transmission, data  reception acknowledgment, error detection and correction, request to terminate transmission, and termination acknowledgment.


RAID

Redundant Array of Independent (formerly Inexpensive) Disk drives. Sometimes called a Disk Array. Essentially, a grouping of either IDE or SCSI drives connected in such a manner and controlled by software or hardware to allow simultaneous access to multiple  drives, redundant data storage, mass storage capability, and dependent upon the configuration selected, hot swapping or replacement of defective drives with no loss of data.


RAM

Random Access Memory. This type of memory won’t retain data after power is turned off.


RISC

Reduced Instruction Set Computer. This type of processor architecture requires less complex instructions/commands to accomplish the same activities (read write, add, subtract, multiply, divide, move, etc.) as CISC, or  complex instruction set computers. Because of this, RISC  processors require less transistors and thereby have smaller silicon chip sizes and costs compared to CISC processors. They can also perform similar operations faster than a CISC processor.


ROM

Read Only Memory. This type of memory retains data after power is turned off. Data cannot normally be written to this type of memory.


Scatter/Gather

A host computers operating system often doesn't have a single large data buffer available for data transfer. In this case a S/G list can be used by the host adapter to make use of the smaller chunks of available memory.  Each entry in the list contains an address & transfer length pair.  The S/G list is given to the host adapter and in the case of a read it scatters the data from the SCSI device all over the systems memory using the S/G list.  In the case of a write the host adapter gathers the data from various parts of memory and transfers it to the SCSI device.. All this is done without bothering the host CPU.


SCSI

Small Computer Systems Interface. ANSI standard specification for a peripheral bus and command set. High performance peripheral interface that distributes data among peripherals  independently of the host to free the host computer for other user-oriented activities. Offers important capabilities not available in EIDE, including multi-threaded task handling high data transfer rates, broad peripheral support and greater connectivity appropriate for high-end PCs, workstations, network servers disk arrays and minicomputers.

See Also: SCSI 2, SCSI ID , Wide SCSI and Fast SCSI


SCSI 2

An enhancement to SCSI. It offers two major improvements, Fast SCSI and Wide SCSI. The SCSI 2 specification allows a manufactuer to offer either the Fast option or the Wide option or both. A manufacturer can also be SCSI 2 compatible but not offer the Wide or Fast options. Western Digital's PCI-SCSI Host Bus Adapters offer both wide and fast options.


SCSI Cable

One of several types of cabling that connect SCSI devices.


SCSI ID

A number assigned to a device connected to the SCSI bus. It must be unique. For example there can be only one device with an ID of 0, one with an ID of 1 etc.

The ID’s are numbered from 0-7 for SCSI I and 0 -15 for SCSI 2. The Host Bus Adapter is often assigned ID 7 to ensure that it has the highest priority on the SCSI bus.

(Note: 7 is the highest priority even on a wide SCSI bus with16 SCSI ID's.)


Single Ended

Electrical signal configuration using a single line to carry each signal . Primarily for applications within a cabinet and uses cabling up to 6 meters  (19.86 feet).


Single Threaded

The ability to work on a single task at once. As opposed to Multi-threaded the ability to work on several tasks at once. See Thread. See also Task.


Synchronous Transmission

Transmission in which the sending and receiving devices operate  continuously at the same frequency and are held in a desired phase  relationship by correction devices or phase lock loop circuits. For  buses, synchronous transmission is a timing protocol that uses a master clock and has a clock period.


Target

Receives and carries out commands from the initiator; e.g. a SCSI Host Bus Adapter or a other device on the SCSI bus.


Task

Operations conducted within a system such as updating a file, writing to the hard disk, writing or reading from an I/O port. Multi-tasking operating systems can execute multiple operations concurrently, initiating additional data transfers before the previous commands have completed. This allows the CPU to queue commands to the storage subsystem and continue on with other  operations, which improves system performance. The SCSI protocol provides a mechanism for handling multiple threads, but intelligent queue management is required.

The latest generation of Western Digital SCSI controller chips have on-chip processors that manage these queues which were previously managed by the CPU via interrupts.


Terminator

A device to reduce electrical noise on a SCSI bus. A SCSI bus must have two terminators, one at each end of the SCSI bus. Western Digital PCI-SCSI 2 Host adapters includes a terminator on the circuit board.

There are two methods of termination:

Active Termination          Passive Termination


Thread

A thread is a single task or data transfer command from the host CPU. (Synonymous to task.)


WCS

Writable Control Store. A high-speed, programmable sequencer that manages the SCSI bus protocol, including arbitration, selection, message transfer and data transfer. Operates independently from the host adapters internal RISC processor and can execute SCSI bus protocols in less than 20usec.


Wide SCSI

A 16 bit parallel data transmission path compatible with the SCSI 2 specification. If a SCSI bus is not "wide" then the data path is 8 bits wide.


Western Digital

The Company

Founded in 1970 as a specialized semiconductor manufacturer, Western Digital today manufactures hard drives for the mainstream personal computer market. The company also designs and sells an array of microcomputer products consisting of integrated circuits and board products which perform or enhance graphics, storage, communications, and logic functions.

We create some of the most respected and award-winning products in the personal computer industry.

 Hard Drives - Western Digital is a leading supplier of Caviar 3.5-inch, AT-IDE hard drives for personal computers and  offers 2.5-inch drives for mobile computers. We pioneered the Enhanced IDE interface technology and were first to introduce an inch-high, three-platter Enhanced IDE drive with 1 gigabyte of storage capacity.

 I/O Products - We've answered the need for high-speed data communications by offering semiconductor devices, software and board designs that target high-speed I/O channels such as PCI-SCSI, EIDE, P1394 (Fire Wire), SSA and Fiber Channel.


 Technical Support

Support is availible to help you with any difficulties you may encounter with your host adapter.

Western Digital BBS: (714) 753-1234

8 data bits, No Parity,  1 Stop bit. Baud Rates up to 14.4k

Please call the BBS for software updates and the voice line for problem resolution.

German  BBS  49-89-92 20 06-60

English   BBS  44-137-236-0387

Western Digital's Web site: http://www.wdc.com.

Western Digital's FTP site: ftp.wdc.com.

America On Line:  keyword "wdc"  (Type Ctrl-K and enter the word "WDC")

Microsoft Network:  Goword "WDC"

Western Digital Technical Support: (800) 832-4778 or (714) 932-4900

Technical Support Fax: (714) 932-4012

Outside the U.S. dial (714) 932-5000

Before contacting Western Digital please have the following information availible:

1.	The maker of your computer system

2.	The maker of your system BIOS. (usually displayed at boot time.)

3.	The version numbers of your device driver and Host Adapter Bios

4.	The version number of your operating system (and build number if applicable)

4.	The EXACT contents of you configuration files. (config.sys, autoexec.bat etc.)

5. 	As best you can, have a CLEAR description of what the problem is.

Western Digital technical support wants to help you! By having the information above ready when you call we can more easily assist you. If you can't obtain all of the information above just get as much of it as you can.


33c196
WD33C296A

This is the 'brain" of the host adapter. It connects the PCI bus to a Fast-Wide SCSI-2 bus.

This  is a very high performance device which can move data between a SCSI device to a PCI host system with no host intervention. This allows the host CPU to work on other things and leave the details of an I/O operation to the host adapter, improving overall system performance.

It has the following features:

   16 MIPS RISC processor which is programmable in assembly language.

    Wide SCSI and Fast SCSI compatibility.

    Controls Up to 15 SCSI peripherals.

    High performance WCS for fast SCSI bus operations with low overhead.

    Data Transfers at up to 20 MB/S over the SCSI Bus.

    Data Transfers at up to 132 MB/S over the PCI bus.


ROM Bios

This chip contains code which allows the SCSI host adapter to boot up a system from a SCSI disk drive.

It supports up to 15 disk drives on the SCSI bus. This is also where the setup program resides. On some Western Digital Host Adapters the BIOS code is stored in flash memory rather than on a rom memory chip.


50 Pin connector

 This is the 50 pin internal connector to connect the Western Digital host adapter to 8 bit SCSI peripherals.


68 Pin Internal connector

 This is the 68 pin internal connector to connect the Western Digital host adapter to 16 bit ( Wide ) SCSI peripherals.


Crystal
Oscillator

This is the Oscillator which provides timing signals to the devices on the host adapter..


68 Pin External Connector

 This is the 68 pin External connector to connect the Western Digital host adapter to SCSI peripherals outside of the system case.


Active Terminator

This chip actively terminates the signals on the SCSI bus.


Address Latches

These chips are electronic components called latches.


Temp Title 62AB
Auto Termination

This device will automaticly determine if the SCSI bus needs to be terminated and if needed will provide active termination.


Static RAM

These devices are a fast type of memory which the host adapter uses to process I/O requests. By having memory on the host adapter board itself the host computer memory is freed for use by applications. This memory also reduces the need for the host adapter to transfer data over the PCI bus thus freeing the PCI bandwidth for use by the host computer. Static Ram is only offered on the 7296 host adapter.]


Fuse

This is a fuse used to protect the host adapter from excess current. It will automaticly reset after a short time.


Flash Memory

This is a Flash memory chip. It retains information after power is turned off. It is used to store the BIOS code. Unlike host adapters from other companies the Western Digital PCI-SCSI host adapter can be upgraded without having to replace a ROM chip. The upgrade is easily done by running a program.


Busy Light

This connector allows you to connect your host adapter to an LED on the front panel of your computer system. It then lights up when a SCSI device is accessed.


Diode

This is an electrIcal component used to protect the host adapter.


PCI Connector

This stub plugs in to a PCI bus socket to connect the SCSI 2 Host adapter to a PCI local bus .


Version

Version:	1.4

PCI to SCSI 2 Help file

P/N 84-000453-000

Copyright 1994,1995 Western Digital Corporation

All Rights Reserved

This file was developed by Western Digital in Irvine, Ca  U.S.A

by Western Digitals I/O Products division.

Corel & CorelSCSI are trademarks owned by Corel Systems Corporation.

MS-DOS is a trademark owned by Microsoft Corporation.

Created By Bob Daniel.

Western Digital I/O Products


Data Reliability
A: Check two things. First make sure that you have the SCSI bus terminated correctly (See installation instructions for information on termination). Second make sure you are using high quality cabling. Do not use low quality cables.


SCSI ID Problems
A: Did you set the SCSI ID to an unused value?  For instance disks are often shipped with ID 0. If you already have a device with a SCSI ID of 0 you must consult the disk drive manual to determine how to change the new device to an unused SCSI ID (See the configuration and setup section of the installation manual).


Adding a Fast Wide device
A: When adding a Fast or Wide SCSI device you must go in to the setup menu and turn the wide option and the synchronous option  to initiate. This tells the host adapter to communicate with the SCSI ID of your device in the proper manner. (See the configuration and setup section of the installation manual).


Adding and 8 bit device
A: Go in to the setup menu and turn off the wide option.  Disable synchronous negotiation if it is not a Fast SCSI device. Older SCSI devices will not support the Fast or Wide options. If you want to attach  an 8 bit external device to your 7296 host adapter you can purchase an adapter from you local computer store to make the connection from  a 16 bit cable to an 8 bit device.


EMM386.EXE issue
A: If you load an older version of EMM386.EXE via your config.sys file this could cause a problem. Older versions of EMM386.EXE have a conflict with PCI  local bus systems.

There are several solutions. You can obtain the latest version from Microsoft (You'll need version 4.49 or later). Or if you have no programs that require expanded memory you can delete the line from your config.sys file.

Click here to find out how to determine what version of EMM386.EXE you have.


EMM386 Version

To determine what version of EMM386.exe you are using:

Change to your root directory and edit your config.sys file.

Look for a line that has "Device=C:\windows\emm386.exe" There may be extra text on this line. This line lists the sub-directory for the copy of EMM386.EXE you are using.

Change to the sub-directory that contains your copy of EMM386.EXE.

Type EMM386.EXE. A version number will be displayed.

CAUTION:

Many systems contain more than one copy of EMM386.EXE. If you load one copy in your config.sys file but are in a sub-directory that contains a copy you are not using. The version number of EMM386.EXE from the current sub-directory will be displayed.

It is important to get the version number of the copy you are using in your config.sys file.


Win 95 Driver
A: A driver for Windows 95 Release 490 is actually included on the Windows 95 CD.

It is not included as one of the built in drivers though. It will be built in to future releases of Windows 95.   To use the Windows 95 driver rather than the DOS driver you need to do the following:

Go into the control panel and select  the system icon.

Click the device manager tab

Double click the SCSI controllers icon.

Double click the Western Digital WD7296A SCSI host adapter line.

Click the driver tab.

Click the change driver button

Click the have disk button.

If you have a FLEXware floppy disk insert it in the drive and click O.K. there is no Windows 95 sub-directory, the driver for the host adapter is located in the root directory.

If you do not have the FLEXWARE disk use the browse button to  browse to your CD rom drive to  \drivers\storage\Wd

Then click O.K.

If you do not have either the Windows 95 CD or a FLEXware diskette  you can download the Windows95 driver from one of Western Digital's on-line services.

The most up to date driver (which will fix problems occuring with older drivers) will be available on one of Western Digitals on line services. Click on download to find out where to obtain the latest driver.  If you do not have access to on line services you can contact our Western Dgital's Technical support department.


NO IRQ in Setup
A: Most PCI systems automatically configure cards plugged in to a PCI slot. Some systems require you to go in to the system setup menu and manually configure each PCI slot. You must have the host adapter in a bus mastering slot. The slot must be assigned a unique IRQ (often 9,10 (0ah)  or 11 (0bh) and an I/O address). If you are running Windows 95 then settings in the resources tab in System Properties must match the settings in the system setup menu as far as IRQ, I/O space and address space.