Adaptec AHA-1744 Instalační příručka

adaptec AHA-1740A/1742A/1744 EISA-to-Fast SCSI Host AdapterTechnical Reference Manual

SCSI Messages ...9-3Target Mode SCSI Description

Echo Command Data (Operation Code 1F)This command is used to test the Command/Data Out Port, the Data In Port, and theassociated control bits in the o

BaseAddr+0 CMD CCB 4 Pointer MBO 0+4 CMD CCB 2 Pointer MBO 1+8 00 Free Entry MBO 2+12 CMD CCB 3 Pointer MBO 3+16 00 Free Entry MBO 0+20 Status CCB 1 P

The MBO format is described in detail below:Byte Description Value Meaning0 MBO CommandThis byte specifies the state ofthe MBO entry.00h Mailbox Out i

host adapter will not change the MBOA interrupt bit and will continue to scanfor other stored MBO entries. 3. If interrupts other than the Mailbox Out

Mailbox In Format for CCB CompleteByte Description Value Meaning0 MBI StatusThis byte specifies the state ofthe MBI entry.00h Mailbox In is free01h CC

Byte Definition Value MeaningBit 3 The SCSI Target commandreceived was a Send command.A CCB must be prepared totransmit data from the Initiator.Bits 2

NoteCareful host Target Mode software design is necessary to prevent ambiguity in thenotification process. If a CCB was just prepared but the MBO has

Byte Description Value Meaning7-9 Data Pointer (Byte 7 mostsignificant)10-12 Link Pointer (Byte 10 mostsignificant)13 Command Linking Identifier14 Hos

The standard format of the Command Control Block is shown in the followingdiagram:Byte 0 Command Control Block Opcode1 Tar/Init Data Out Data In LUN2

AHA-1740A/1742A/1744. Operation codes 00h and 03h differ only in the updating ofBytes 4, 5, and 6, following completion of the command.If the operatio

PrefaceThis Technical Reference Manual provides technical information for Adaptec’sAHA-1740A/1742A/1744 EISA-to-Fast SCSI Host Adapters. It is prepare

Mode CCB, the handling of incorrect lengths is described in Incorrect Length Manage-ment for Target Mode Operation in Chapter Nine, SCSI Features. If

This byte indicates the length, in bytes, of the area reserved for information that maybe obtained by a Request Sense command. A value of 00h indicate

set, an interrupt will be generated before the next command is started. A completedCCB is always reported back in an MBI, but MBIF interrupts are only

Byte 15: Target StatusFor an initiator CCB, this byte is used to return the SCSI status byte sent to the hostadapter from the initiator. If a SCSI com

Scatter/Gather List DefinitionUsing the normal CCB operation codes of 00h and 01h (SCSI Initiator and SCSI Tar-get CCBs), the CCB itself contains a po

The actual boundary limitation is somewhat less restrictive. If the binary values ofthe starting address of a segment, the byte count of that segment,

If a check condition status is received from the target, the AHA-1740A/1742A/1744will issue a Request Sense command to get the sense data. The sense d

in the MBI by an interrupt from the host adapter. The host then prepares a newCCB to control the target’s next activity expected from the initiator.E

DMA Channel DMA Controller Port Data00B0A0C005D6D4C1016D6D4C2027D6D4C303Interrupt InitializationThis setup procedure is normally completed by the BIOS

Interrupt Mask Bit Definition (Port Address A1h)Bit Interrupt0 Int 81 Int 92 Int 103 Int 114 Int 125 Int 136 Int 147 Int 15❏EISA-to-Fast SCSI Host Ada

ConventionsThe following typographic conventions are used throughout this Technical ReferenceManual.boldUsed for keystrokes (.. press the Enter key ..

Chapter SixEnhanced Mode Firmware DescriptionIntroductionThe Enhanced mode is an interface architecture which allows the AHA-1740A/1742A/1744 to take

The host then checks the busy bit (Bit 0) in zCD7 to ensure that the AHA-1740A/1742A/1744 has serviced any previous requests placed in the Attention r

Control BlockThe control block is a 48-byte structure created and maintained in shared memory bysoftware in the system unit. It is used to convey requ

Command WordThe command word is a 16-bit structured field used to identify the operation to beperformed by the host adapter.Command Word StructureFEDC

Flag Name and FunctionCNE Chain No ErrorThe Chain No Error flag (bit 0) indicates whether control block chaining is enabled.If this bit is set to one,

Flag Name and FunctionDSB Disable Status BlockThe Disable Status Block flag (bit 14) indicates whether the status block is to bestored.If this bit is

Flag Name and FunctionLUN Logical Unit NumberThis field (bits 2-0) specifies the logical unit number of the target for which the com-mand is to be exe

Flag Name and FunctionDAT Data Transfer - Check DirectionThis flag (bit 8) determines whether the host adapter should verify the direction ofthe expec

Flag Name and FunctionST Suppress Transfer to Host MemoryThis flag (bit 10) indicates whether an incoming data transfer is to be suppressed.This flag

Chapter OneIntroductionDocument ScopeThis manual provides information on installation and defines the program interfacesof the AHA-1740A/1742A/1744 in

Flag Name and FunctionREC Error RecoveryThis flag (bit 14) is used by the host to perform error recovery procedures while theassociated target is in a

1F1E1D1C1B1A19181716151413121110FEDCBA9876543210Data Pointer 1Data Length 1Data Pointer 2Data Length 2...Data Pointer nData Length nThe data lengths m

Chain AddressThis 32-bit field contains the physical memory address (least significant byte first) ofthe next control block to be processed by the hos

SCSI Command Descriptor BlockThis 6-, 10-, or 12-byte field contains the actual CDB to be sent to the target duringcommand phase.Status BlockThe statu

Status WordThe status word is a 16-bit structured field used to hold flags indicating how the com-mand for the associated control block is completed.F

Flag Name and FunctionSC Specification CheckThe Specification Check flag (bit 4) indicates that the host adapter detected an errorin the control block

Flag Name and FunctionSNS Sense Information StoredThe Sense Information Stored flag (bit 9) indicates whether the target’s senseinformation has been s

Host Adapter StatusThis 8-bit field contains additional error information pertaining to the host adapteror SCSI subsystem in general. This field is va

Code Description04 Condition Met (For Search Data and Pre-Fetch SCSI Commands)10 Intermediate (For Linked SCSI Commands)14 Intermediate Condition Met1

If Scatter/Gather was enabled for the associated control block, then this field con-tains the address of the data pointer in the Scatter/Gather list t

AHA-1740A/1742A/1744 Product FeaturesEISA FeaturesThe AHA-1740A/1742A/1744 is a full-performance EISA board offering the highestperformance available

765432100 1 0 0 SCSI IDThe SCSI ID specifies either the SCSI address of a particular target or initiator, orthe SCSI address of the host adapter. The

Download FirmwareFEDCBA9876543210 ByteOffset0 Options 000000001001 00Flag Word 1 02Flag Word 2 0406Pointer to firmware 080ALength of firmware 0C0EStat

After a Hard Reset, the host adapter will default to the firmware stored in itsEEPROM.If the Configure flag (PORTADDR register, bit 6) is set to one,

Initialize SCSI SubsystemFEDCBA9876543210 Byte Offset0000000000000110 00Flag Word 1 020406Pointer to Initialization Configuration Data 080ALength of I

field contains the number of bytes available to the host adapter. The maximum num-ber of bytes read by the host adapter will be 32.If this command is

All bits not defined above are ignored by the host adapter and may be set to either 0or 1.The Disconnection Enable bit (least significant byte, bit 2)

Initiator SCSI CommandFEDCBA9876543210 ByteOffset0 Options 000000000001 00Flag Word 1 02Flag Word 2 0406Data or Scatter/Gather List Pointer 080AData o

No OperationFEDCBA9876543210 ByteOffset0 Options 000000000000 00Flag Word 1 02Flag Word 2 0406080A0C0EStatus Block Pointer 1012Chain Address 1416181A1

If the SCSI ID specified in the Attention register specifies the SCSI address of a par-ticular target, then this command is intended to queue an inter

Read Host Adapter Inquiry DataFEDCBA9876543210 ByteOffset0 Options 000000001010 00Flag Word 1 020406Destination Pointer of inquiry data 080ALength of

• Internal and external SCSI connectors• Initiator and target modes of operation fully supported• Differential SCSI (AHA-1744 only)• SCSI-1 and SCSI-2

number of bytes this command supports is 256. The host adapter may not transferthe total number of bytes allocated, therefore, the Suppress Error on U

FEDCBA9876543210 ByteOffsetSCSI Device Type 00SCSI Support Level 02No. of LUNs Additional Lng 04Flags No. of CBs 06Vendor Verification 080A0C0EProduct

The SCSI device type word contains the following information.FEDCBA98765432100 Reserved 0 T T 0 0011MMSDBits 4-0 will be set to a value of 03 indicati

7654321000WSLD00IYNIDNKFBit 2 indicates whether the board SCSI electrical interface is Single-Ended/AHA-1740A/1742A (bit reset) or Differential/AHA-17

Read Sense InformationFEDCBA9876543210 ByteOffset0000000000001 0 00Flag Word 1 02Flag Word 2 0406080A0C0EStatus Block Pointer 10121416181ASense Inform

contingent allegiance was reported in the status block of the Initiator SCSI com-mand, this command must be followed by a Resume command to release ex

Run Diagnostic TestFEDCBA9876543210 ByteOffset0 Options 000000000101 00Flag Word 1 02Write FIFO Data Pointer 0406Read FIFO Data Pointer 080ATest FIFO

Value Meaning000 Self-TestThe host adapter performs a subset to its self-diagnostic routines that it normallyperforms at power-up. The two data pointe

Target SCSI CommandFEDCBA9876543210 ByteOffset0000000000010000 00Flag Word 1 02Flag Word 2 0406Data or Scatter/Gather List Pointer 080AData or Scatter

Supported Options• Flag Word 1 - Scatter/Gather (bit 12) is supported. Suppress Error on Underrun(bit 10) should be used with care since the exact len

mode dictates the software manager revision which can support the board, but hasno effect on the SCSI or host bus hardware connections.Standard Mode a

Control Block is Queued for OperationA control block is queued for operation when it has not yet initiated any activity onthe SCSI bus. The host adapt

Asynchronous Event NotificationAn asynchronous event occurs when the host adapter detects an unexpected condi-tion on the SCSI subsystem.Asynchronous

Host Adapter Selected by Another InitiatorIf the host adapter is selected by another initiator on the SCSI subsystem, the hostadapter will respond as

765432100 0 0 1 SCSI IDThe SCSI ID specifies either the SCSI address of a particular target, or the SCSI ad-dress of the host adapter. The host adapte

completes, with or without error, and the host adapter has not yet issued the inter-rupt to the host. The action taken on the target depends on the se

returned will reflect that the command was aborted by the host adapter (errorcode = 05). Any commands received after the acknowledgment of the Asynchr

ResumeFEDCBA9876543210 ByteOffset10010000 00102Fields that are empty are reserved and should be set to zero.This command is used to clear an extended

Reset Initiated by the Host AdapterThe host adapter will reset the bus if it encounters an error on a SCSI operation thatit cannot recover from. Some

Asynchronous Event Notification interrupt will be returned with error status.The status returned will reflect that the command was aborted by the host

Chapter SevenOnboard BIOS InterfaceIntroductionThe AHA-1740A/1742A/1744 BIOS operates in two different modes which correspondto the two possible firmw

Product SpecificationsPhysical DimensionsLength 13-3/8 inchesWidth 5/8 inchHeight 5 inchesStandard EISA-compatible form factor.Power Requirements+5.0

attached SCSI devices depends on the number of standard hard disks installed di-rectly on the system.No Standard Hard Disks InstalledIn this case, two

BIOS base address in the boards setup registers. In the case where the board isnot functioning properly, the BIOS will display the message: Unable to

Other ChangesThe BIOS is interrupt driven in Enhanced Mode and fully supports Int 15h allowingoperation with various write caching programs. The BIOS

AHA-1740A/1742A CMOS configuration so the desired boot drive is the first drivefound by the system.Interrupt 13h Interface FunctionalityDisk I/O reque

system processor is in real mode. Because this is the case at system boot time and un-der normal DOS operation, simple segment arithmetic is normally

AH (Hex) Definition11 ECC Corrected Data Error: Returned SCSI ASC: 17h - Recovered Read Error without ECC 18h - Recovered Read Error with ECC20

The ID of the first supported drive is returned in BL. If an error code is returned (Cis set) on this call, it indicates that the SCSI adapter BIOS is

The output of this function is defined as follows:Register FunctionAH Status of OperationDL 00h - Drive not present or invalid DL03h - Fixed Disk Pres

• In Standard Mode, disk devices must be installed sequentially starting at target 0Multiple Adapter SupportWhen multiple SCSI adapters are installed,

Appendix AMemory Cycle Timing DiagramAHA-1740A/1742A/1744 Timing DiagramA-1

SCSI InterfaceElectrical Interface for AHA-1740A/1742AAs specified by ANSI X3.131-1986 for single-ended operation.Output SignalsAll signals use open c

EISA AccessNumber Definition1 EISA Standard Access (Start of Burst)2 EISA Burst Access3 EISA Burst Access with One Wait State4, 5 EISA Burst Access6 E

Appendix BConnector PinoutInternal Connector Pin AssignmentsAHA-1740A/1742A (Single-Ended)Signal Name Pin Pin Signal NameGround 1 2 -DB(0)Ground 3 4 -

AHA-1744 (Differential)Signal Name Pin Pin Signal NameGround 1 2 Ground+DB(0) 3 4 -DB(0)+DB(1) 5 6 -DB(1)+DB(2) 7 8 -DB(2)+DB(3) 9 10 -DB(3)+DB(4) 11

External Connector Pin AssignmentsAHA-1740A/1742A (Single-Ended)Signal Name Pin Pin Signal NameGround 1 26 -DB(0)Ground 2 27 -DB(1)Ground 3 28 -DB(2)G

AHA-1744 (Differential)Signal Name Pin Pin Signal NameGround 1 26 Ground+DB(0) 2 27 -DB(0)+DB(1) 3 28 -DB(1)+DB(2) 4 29 -DB(2)+DB(3) 5 30 -DB(3)+DB(4)

Appendix CRegister ReferenceSystem Register ReferenceExpansion Board IDsDefinition Signal EISA Slot Write/ReadHost ID 0 HID0 zC80 RHost ID 1 HID1 zC81

Definition Signal EISA Slot Write/ReadMailbox In Byte 2 MBOXIN2 zCDA RMailbox In Byte 3 MBOXIN3 zCDB RGroup 2 Status 2 G2STAT2 zCDC RControl Group 1 (

Definition Signal Address (hex) Write/ReadLocal Mailbox In Byte 2 LMBOXIN2 3016 WLocal Mailbox In Byte 3 LMBOXIN3 3017 WLocal Group 2 Control LG2CNTRL

Appendix DEISA Free-Form DataSCSI Subsystem Data StructureSCSI Device Byte Bit Definitions00Bit 7 - Allow removable media in BIOS disk scanBit 6 - Mor

Electrical Interface for AHA-1744As specified by ANSI X359.2/86-109 Rev. 10h for differential alternatives.Output SignalsEach signal driven has the fo

STOCK NO.: 510208-00Rev.AGM 3/92Printed in Singaporeadaptec691 south milpitas blvd. • milpitas, ca 95035 • (408)945-8600

Copyright© Copyright 1992 Adaptec, Inc. All rights reserved. No part of this publication may be reproduced, stored in a re-trieval system, or transmit

External ConnectorShielded 50-pin high density (Alternative 1) connector as specified in proposed ANSIstandard X3T9.2/86-109 Revision 10h, Section 4,

Floppy Disk InterfaceStandard Electronic and Physical interfaceDriver Output SignalsVOL0 volts minimum 0.5 volts maximumVOHOpen collector 5.25 volts m

• Adaptec AHA-1740A/1742A/AHA-1744 Host Adapter Installation Guide Us-ing the ASW-C174• Intel® 82077A Floppy Disk Controller Data Sheet❏adaptec AHA-17

Chapter TwoArchitectureHardwareThe hardware of the AHA-1740A/1742A/1744 products is based on the latest VLSItechnology for maximum performance in a mi

Bus Master DMAThe AHA-1740A/1742A/1744 controls the host EISA bus as a master and transfersdata directly to and from main system memory. This implemen

synchronous and asynchronous peripherals can be freely mixed on a cable connectedto the AHA-1740A/1742A/1744.In addition, the host adapter has the abi

EISA Configuration Chip (AIC-575)The host adapter provides a number of options which may be programmed at configu-ration time. They are summarized bel

systems with a large amount of bus latency, typically found in performance EISAsystems.Standard Mode FirmwareThe AHA-1740A/1742A/1744 support multithr

A typical mailbox structure is:Base Adr+0 CMD CCB 4 Pointer MBO 0+4 CMD CCB 2 Pointer MBO 1+8 00 Free Entry MBO 2+12 CMD CCB 3 Pointer MBO 3+16 00 Fre

A typical CCB is shown below:Byte 0 Command Control Block Opcode+1 Tar/Init Data Out Data In LUN+2 SCSI Command Length = m+3 Returned Sense Info Lengt

FCC Compliance StatementNOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuantto Part 15 of t

Please refer to the SCSI specification ANSI X3.131, the Common Command Set(CCS) revision 4B, and the SCSI-2 draft for additional information on Comman

The host adapter dequeues on a first in, first out (FIFO) basis for each target/LUNcombination. However, due to the optimization algorithm used by the

The control block is a 48-byte structure created and maintained in shared memory bysoftware in the system unit. It is used to convey requests to the h

Onboard BIOS OperationA host adapter BIOS is provided to emulate the standard hard disk BIOS and bootfunctions. With this BIOS, the host adapter can b

Flash Code Possible Meanings of Flash CodeLED Remains On Host Adapter Control Processor inoperative, terminators missingor not powered, or card enable

The utility disk will also include copies of the microcode files for the AHA-1740/1744to be downloaded by the download utility. These are normally not

Chapter ThreeInstallationUnpacking and InspectionThe carrier is responsible for damage incurred during shipment. In case of damage,have the carrier no

WARNINGConnection of a single-ended board to a differential drive or vice versa may causepermanent electrical damage to one or both devices.System Con

Each EISA system is shipped with a configuration utility to assign parameters suchas port addresses and interrupt priorities to boards installed in th

iv

SCSI ParityCheck all SCSI devices to ensure that they generate parity. If any SCSI device doesnot generate parity, then all SCSI devices should be set

To perform hardware installation:1. Turn off the power to the computer system.2. Remove the cover of your EISA personal computer to expose the EISA bu

7. Align the EISA bus connector on the bottom of the AHA-1740A/1742A/1744 to theopen chassis slot with the slot cover removed. Ensure the external con

selected for external SCSI devices must not overlap with the addresses of thehost adapter or any other SCSI devices attached internally.Generally spea

2. Ignore any error which indicates that an unknown board has been detected in thesystem. Selection of board configuration varies with the configurati

MCS ConfigurationFor configuration under MCS, select the slot in which the AHA-1740A/1742A/1744 isinstalled and press Enter. The screen will display t

When Enhanced Mode is selected, IRQ 11 is used by default. By default, if multipleAHA-1740 family host adapters are in the system in Enhanced Mode, al

Standard Mode SCSI ConfigurationThe view for Standard Mode is a simple selection for those variables which apply toall SCSI peripherals connected. Thi

Enhanced Mode SCSI ConfigurationThe view for Enhanced Mode allows more flexible selection and is shown in Figure 3-6.The enhanced mode offers a greate

Send Start Command is used for devices which require a command to start up af-ter power on. Most devices do not require this.Enable Parity Check is si

Table of ContentsPreface...

When the selection is completed, press Esc to reach the SCSI configuration exitmenu shown in Figure 3-8.Use the cursor keys or mouse to select whether

Phoenix ConfigurationConfiguration using the Phoenix utility is similar to that under MCS. Use the arrowkeys to select the board to configure after en

• 32-bit addresssing capability• Single fast mailbox handling• Contingent allegiance (SCSI)• Tagged queueing (SCSI)• 10 MBytes/second Fast SCSI data t

• Download Firmware• Firmware Information• Low-Level FormatUse the up and down arrow key to choose the operation. Press Enter to start an op-eration.

Subsequently, a confirm message window will be displayed to allow verification ofthe download operation. If the displayed information is valid, press

Chapter FourHardware Functional DescriptionHardware OverviewThis section provides a description of the AHA-1740A/1742A/1744 hardware fun-tional interf

The base port is for control and status, the second port for command and data trans-fer, and the third port for interrupt flags.I/O Port Interface Bit

Control and Status PortWriting a one to the bits of the Control Port initiates certain special host adapter op-erations. There is no requirement to re

continue after the reset occurs. See the section on Reset Functions describing theoverall reset structure.Bits 0-3 - ReservedReserved bits must be set

Bit 2 - Data In Port Full (DF)The host uses the DF bit to synchronize transfers of data from the host adapter to thehost. When the DF bit is set to on

ASW-C174 Configuration Diskette...2-12Chapter Three - InstallationUnpacking

terminated abnormally. The use of CDF as a handshaking bit is required to preventthe transfer of invalid data.If an adapter command requires data tran

Bit 3 - SCSI Reset Detected (SCRD)This bit, when one, indicates that a SCSI Reset has been received on the SCSI bus.The Any Interrupt bit and the AT i

Mailbox In entries, so the host should check the next entry to determine if more thanone set of information has been provided. The MBI entries are fil

SCSI Reset OperationsThe SCSI Reset condition is defined in the SCSI Standard, X3.131-1986, Section5.2.2. A SCSI Reset condition may be forced by any

The SCSI Soft Reset option is useful in multitasking systems that cannot tolerate theoverhead of a complex reconfiguration and reinitialization after

resources such as interrupt levels and DMA channels when they are assigned. Referto the EISA Specification, Section 2.6 and Section 3.3 for more infor

Host ID 1 (HID1, zC81, R)HID1 is the second byte of the expansion board ID. It is written by the local processorand read by the system processor. RESD

I/O Port Address (PORTADDR, zCC0, W/R) PORTADDR selects the base address for the I/O port interface. It is compared withthe system address every cycle

BIOS Address Register (BIOSADDR, zCC1, W/R) The BIOSADDR register maps the BIOS to one of 12 locations between C0000h andEFFFFh at 16K boundaries. In

Interrupt Definition (INTDEF, zCC2, W/R)An interrupt channel may be selected from one of several on the EISA bus. The inter-rupt may be programmed as

Digital Output Registers (Write 3F2) ...4-23Diskette Controller Registers (Read/write

SCSI Definition (SCSIDEF, zCC3, W/R)Programming this byte sets up basic SCSI parameters. Bit Definition7-5 Reserved (0)4 RSTPWR When set, the host ad

Reserved RegistersThe following registers are reserved for future use.• Reserved 0 (RESV0, zCC5, W/R)• Reserved 1 (RESV1, zCC6, W/R)• Reserved 2 (RESV

system STATUS register and this state means that a hardware error has occurred onthe board.Control Port (CNTRL, Base address + 0, W)The Control Port i

Bit Definition2 HAVAIL Information is Available to the system. When this bit is one, the local pro-cessor has loaded CMD/DAT (Base + 1) with data. I

I/O Port Register Enhanced Mode (Group 2)These registers are used for operating in Enhanced Mode and may be used at anytime. They consist of mailbox o

adapter fails diagnostics, then the local processor will load the value appropriate forthe failure in MBOXIN0, according to the following list, and re

Mailbox in 3 (MBOXIN3, zCDB, R)This is the most significant byte of a 32-bit address pointer to a CCB or additionaldata for an immediate command. Atte

Enhanced Mode (Group 2) Status (G2STAT, zCD7, R)Bit Definition7-3 Reserved2 Mailbox out empty Set to one by firmware when it is done with the mailbox

Bit Definition7 Reserved (set to 0)6 Reserved (set to 0)5 Drive B Motor Enable4 Drive Motor Enable3 Enable diskette interrupts and DMA2 Diskette funct

• Command Phase: The processor issues a sequence of write commands to thediskette controller that direct the controller to perform a specific operati

Interrupt Initialization...5-32Chapter Six - Enhanced Mo

Data Rate Delay1 Mps 83.00500 Kps 125.00300 Kps 125.00250 Kps 125.00DRATESEL Data Rate SelectThese bits select the data transfer rate. Reset clears th

Hardware Configuration RequirementsThe following host adapter configuration options must be defined prior to setting thecard enable bit in register zC

BIOS Driver NeedsAt power-on time the BIOS needs information about the SCSI bus to aid in minimumpower-on time and confidence in a complete working sy

Refer to Appendix D, EISA Free-Form Data for the initial SCSI subsystem datastructure.Configuration Byte Description and DefaultsThe following describ

Bit 1 - Ignore error if device not presentThis bit is used by the BIOS only, and does not affect firmware operation. When set,this bit indicates that

Function Configuration Information Data Block for SCSI Subsystem DataByte Offset Description22h Function Information Byte B6 = 1 to indicate free from

Chapter FiveStandard Mode Firmware DescriptionHost Adapter Command OverviewStandard Mode is the mode in which the AHA-1740A/1742A/1744 can operate in

20 Adapter Diagnostic 21 Set Host Adapter Options*This command can be issued when the host adapter is executing a SCSI command.All adapter commands

Mailbox Count. If the Mailbox Count is zero, the INVDCMD bit will be set withHACC to indicate that the parameter is invalid.At command completion, HAC

SCSI Bus Reset Handling...6-46Reset Initiated by the Host...

Byte Description Value Meaning01 Special Options IdentificationThe value in this byte indicateswhat special options aresupported on the AHA-1740A/1742

Set Selection Time out (Operation Code 06)This command sets the SCSI selection time out value. The SCSI Selection time outvalue is used to determine

Set Bus Off Time (Operation Code 08)NoteThis command is not used by the AHA-1740A/1742A/1744 but is supported in orderto be compatible with software w

Data Byte 0 AT Bus Transfer Speed80-FFh Bit Custom Transfer Speed716-4 000 Read Pulse Width (ns) = 100001 Read Pulse Width (ns) = 150010 Read Pulse Wi

After receiving this command, the host adapter returns eight bytes of informationwhich specify the installed configuration as shown below:Byte Configu

Byte Description Bit1 Interrupt Channel Bit 7 Reserved (0)Bit 6 Interrupt channel 15Bit 5 Interrupt channel 14Bit 4 Reserved (0)Bit 3 Interrupt channe

If target mode is not enabled, the host adapter will behave on the SCSI interface as ifit were an ordinary SCSI initiator. Any attempt to select the h

Byte Description Meaning03 Bus Off Time Indicates the Bus Off Timespecified by the Bus Off TimeValue in microseconds (see SetBus Off Time in this cha

Byte Description Meaning10 Disconnection Option Each bit corresponds to a SCSIdevice, e.g., bit 0 corresponds tothe device at SCSI address 0.When set

Read Adapter Channel 2 Buffer (Operation Code 1B)After receiving this command, the host adapter expects three outbound informationbytes to be transfer