Adaptec AHA-1740A Technical Reference Manual
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Adaptec AHA-1740A Technical Reference Manual

Eisa-to-fast scsi host adapter
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AHA-1740A/1742A/1744
EISA-to-Fast SCSI Host Adapter
Technical Reference Manual

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  • Page 1 AHA-1740A/1742A/1744 EISA-to-Fast SCSI Host Adapter Technical Reference Manual...
  • Page 2 Copyright © Copyright 1992 Adaptec, Inc. All rights reserved. No part of this publication may be reproduced, stored in a re- trieval system, or transmitted in any form or by any means; electronic, mechanical, photocopying, recording or otherwise, without the prior written consent of Adaptec, Inc., 691 South Milpitas Blvd., Milpitas, CA 95035.
  • Page 3 Each AHA-1740A/1742A/1744 is equipped with an FCC compliance label which shows only the FCC Identifica- tion number. This device complies with part 15 of the FCC rules. Operation is subject to the following two condi- tions: (1) this device may not cause harmful interference and (2) this device must accept any interference received, including interference that may cause undesired operation.

  • Page 5: Table Of Contents

    Product Specifications ... 1-5 Extended Industry-Standard Architecture Interface ... 1-5 Standard EISA Bus Electronic and Physical Interface ... 1-5 SCSI Interface... 1-6 Electrical Interface for AHA-1740A/1742A ... 1-6 Electrical Interface for AHA-1744... 1-7 Internal Connector ... 1-7 External Connector ... 1-8 Floppy Disk Interface ...
  • Page 6 System Configuration... 3-7 MCS Configuration ... 3-9 Standard Mode SCSI Configuration ... 3-11 Enhanced Mode SCSI Configuration ... 3-12 Multiple Adapters Sharing Same SCSI Bus... 3-14 Phoenix Configuration ... 3-15 Floppy Disk Configuration... 3-15 ADL Utility... 3-15 ADL Operation... 3-16 List of Adapters ...
  • Page 7 Digital Output Registers (Write 3F2) ... 4-23 Diskette Controller Registers (Read/write 3F4 and 3F5) ... 4-24 Digital Input Register (Read 3F7)... 4-25 Diskette Control Register (Write 3F7)... 4-25 Firmware Download (AHA-1740/1744 Only) ... 4-26 Hardware Configuration Requirements... 4-27 SCSI Configuration ... 4-27 BIOS Driver Needs ...
  • Page 8 Table of Contents Interrupt Initialization... 5-32 Chapter Six - Enhanced Mode Firmware Description Introduction... 6-1 Control Block... 6-3 Command Word... 6-4 Flag Word 1 ... 6-4 Flag Word 2 ... 6-6 Data or Scatter/Gather List Pointer ... 6-10 Data or Scatter/Gather List Length... 6-11 Status Block Pointer ...
  • Page 9 SCSI Bus Reset Handling ... 6-46 Reset Initiated by the Host... 6-46 Reset Initiated by the Host Adapter ... 6-47 Reset Initiated by Another SCSI Device... 6-47 Chapter Seven - Onboard BIOS Interface Introduction ... 7-1 Operation with the Standard Interface ... 7-1 No Standard Hard Disks Installed...
  • Page 10 Problems Detected During Installation... 10-6 Chapter Eleven - Glossary Glossary of Terms ... 11-1 Appendix A - Memory Cycle Timing Diagram AHA-1740A/1742A/1744 Timing Diagram ... A-1 Appendix B - Connector Pinout Internal Connector Pin Assignments ... B-1 External Connector Pin Assignments ... B-3 Appendix C - Register Reference System Register Reference...

  • Page 11: Preface

    Preface This Technical Reference Manual provides technical information for Adaptec’s AHA-1740A/1742A/1744 EISA-to-Fast SCSI Host Adapters. It is prepared for cus- tomer technical personnel requiring detailed information on the operation of the board at a register and command protocol level. Documentation of board schematics, integrated circuits, microcode and BIOS routines is not provided.

  • Page 12: Conventions

    Conventions The following typographic conventions are used throughout this Technical Reference Manual. bold Used for keystrokes (.. press the Enter key ..) and screen selection fields (.. select Backup Device and ..). Helvetica Used for operator entry that must be typed exactly as shown ( ..

  • Page 13: Chapter One Introduction

    Disconnect/Reconnect support maximizes bus utilization for multiple target systems. Target mode opera- tion allows the AHA-1740A/1742A/1744 to receive information from other host adapt- ers. Scatter/Gather allows high performance even in systems with fragmented memory buffers.

  • Page 14: Aha-1740A/1742A/1744 Product Features

    EISA-SCB compatible (Enhanced Mode) SCSI Features Adaptec has long been a supplier of leading edge SCSI products and the AHA- 1740A/1742A/1744 is no exception. The board uses industry-standard protocol ICs which fully comply with the 1990 ANSI SCSI specification, including: Maximum synchronous SCSI transfer rate of 10.0 MBytes/second (Fast SCSI)

  • Page 15: Board Features

    AHA-1742A Fast SCSI-to-EISA Host Adapter with floppy diskette controller AHA-1744 Fast differential SCSI-to-EISA Host Adapter The AHA-1740A/1742A/1744 microcode is available in two separate versions which co- exist simultaneously in the onboard PROM, but must be configured into one of the two available modes:...

  • Page 16: Configuration Diskette And Installation Guide (Asw-C174)

    Standard Mode allows software drivers written for the AHA-1540 or AHA-1640 fami- lies to run unaltered on the AHA-1740 family. There is no performance penalty for this on the EISA bus. The AHA-1740A/1742A/1744 still performs 32-bit transfers at speeds up to 33 MBytes/second.

  • Page 17: Product Specifications

    EISA-to-Fast SCSI Host Adapter Product Specifications Physical Dimensions Length 13-3/8 inches Width 5/8 inch Height 5 inches Standard EISA-compatible form factor. Power Requirements +5.0 +/- 0.25 Volts at 2.9 Amps maximum. Environmental Requirements Temperature 0-55 C (operating or storage) Reliability Information Mean Time Between Failures: 100,000 hours (calculated per Mil Handbook 217E, ground benign, 40 Mean Time Between Failures: (calculated)

  • Page 18: Scsi Interface

    SCSI Interface Electrical Interface for AHA-1740A/1742A As specified by ANSI X3.131-1986 for single-ended operation. Output Signals All signals use open collector or three-state drivers. Each signal driven by a SCSI de- vice has the following output characteristics when measured at the SCSI device’s...

  • Page 19: Electrical Interface For Aha-1744

    EISA-to-Fast SCSI Host Adapter Electrical Interface for AHA-1744 As specified by ANSI X359.2/86-109 Rev. 10h for differential alternatives. Output Signals Each signal driven has the following output characteristics when measured at the SCSI device’s connector: Signal Definition Low-level output voltage High-level output voltage Differential output voltage and V...

  • Page 20: External Connector

    Complete cable assemblies are available from a number of manufacturers. Among them are: Manufacturer Amphenol Interconnect Products Lynn Products Inc. Quitec Interconnect Systems Icontec Enhance Cable Technology 1- 8 AHA-1740A/1742A/1744 Model Part Number Connector 749111-4 Back Shell 749193-1 Connector FCN-237R050-G/F...

  • Page 21: Floppy Disk Interface

    EISA-to-Fast SCSI Host Adapter Floppy Disk Interface Standard Electronic and Physical interface Driver Output Signals Receiver Input Signals Tied to +5 volt supply through 150 ohm resistors. Schmidt Trigger with 0.8-volt hysteresis Connector Unshrouded 34-pin header. Partial list of compatible connector plugs (for reference only): Manufacturer T&B Ansley...
  • Page 22 Adaptec AHA-1740A/1742A/AHA-1744 Host Adapter Installation Guide Us- ing the ASW-C174 ® Intel 82077A Floppy Disk Controller Data Sheet 1- 10 AHA-1740A/1742A/1744...

  • Page 23: Chapter Two Architecture

    Chapter Two Architecture Hardware The hardware of the AHA-1740A/1742A/1744 products is based on the latest VLSI technology for maximum performance in a minimum of board space. Where commer- cial products with sufficient performance and functionality were not available, Adap- tec has developed custom circuits using its long experience in high-performance silicon design for peripheral control applications.

  • Page 24: Bus Master Dma

    Bus Master DMA The AHA-1740A/1742A/1744 controls the host EISA bus as a master and transfers data directly to and from main system memory. This implementation is known as Bus Master DMA. Bus Master DMA greatly reduces the host software overhead be- cause the host CPU is no longer required to maintain the DMA channel’s address...

  • Page 25: 8- And 16-Bit Memory And Odd Byte Data Transfers

    Bus Auxiliary Interface Chip (AIC-565) This highly integrated ASIC (Application Specific Integrated Circuit) device devel- oped by Adaptec is also used with the AHA-1540B host adapter family. It provides the Standard Mode programming interface and implements the following main func-...

  • Page 26: Eisa Configuration Chip (Aic-575)

    The microprocessor interface has a 12 mA drive buffer on the data bus plus 100% hardware register compatibility for standard systems. The 16-byte FIFO with programmable thresholds is extremely useful in multimaster systems, or AHA-1740A/1742A/1744...

  • Page 27: Standard Mode Firmware

    Disconnection Reconnection Command completion Using the same mailbox protocol, the AHA-1740A/1742A/1744 can operate as a proc- essor-type device serving as a multitasking target to other initiators. This feature al- lows high bandwidth communication between multiple hosts. In addition, the AHA-1740A/1742A/1744 firmware cooperates with the BIOS in- stalled on the host adapter to emulate the standard DOS BIOS calls.

  • Page 28: Command Control Block

    A Command Control Block is also used to service an operation requested by another initiator when the AHA-1740A/1742A/1744 is being addressed as a SCSI Processor device. The CCB is defined completely in Chapter Five, Standard Mode Firmware Description.

  • Page 29: Command Descriptor Block

    EISA-to-Fast SCSI Host Adapter A typical CCB is shown below: Byte 0 Tar/Init 18 + m Command Descriptor Block The Command Descriptor Block (CDB), a part of the Command Control Block, is a standard format command packet that is transmitted to the addressed SCSI device. It contains all the command information required by the SCSI device to perform the desired operation.

  • Page 30: Principles Of Operation

    Multiple tasks may be started against a target/LUN or against multiple targets/Logi- cal Units. Since only one task can be active against any one LUN at a time, all other tasks for the same LUN are queued. Other LUNs may have active tasks at the same time. AHA-1740A/1742A/1744...

  • Page 31: Enhanced Mode Firmware

    ASW-1440 v3.0 and later (ASPI Manager for Novell NetWare ASW-1450 v1.0 and later (SCSI Manager for SCO UNIX In order to use the Enhanced Mode, the AHA-1740A/1742A/1744 must be correctly re- configured. Use the EISA Configuration Utility (EISA) that came with your EISA sys- tem and the EISA configuration files on the ASW-C174 diskette provided with the AHA-1740A/1742A/1744.
  • Page 32 Command Word Flag Word 1 Flag Word 2 Status Block Pointer Chain Address Sense Information Pointer Sense Length Data Checksum CDB Byte 0 CDB Byte 2 CDB Byte 4 CDB Byte 6 CDB Byte 8 CDB Byte 10 AHA-1740A/1742A/1744 Byte Offset...

  • Page 33: Onboard Bios Operation

    At least one set of terminators must remain installed or the LED will stay on, indicating that the AHA-1740A/1742A/1744 is receiving an active RST signal. The flash code and associ- ated failure modes are indicated in the following table.

  • Page 34: Asw-C174 Configuration Diskette

    Adaptec bulletin board for a download copy of the files. The Adaptec bulletin board number is (408) 945-7727. Use 8 data bits, 1 stop bit, no parity, 1200, 2400, or 9600 baud.
  • Page 35 SCSI bus and the specific structure within the freeform data area and is not specified by the EISA specification. Adaptec uses a data structure for each device (SCSI ID #n) consisting of two bytes, shown in the following table:...

  • Page 37: Chapter Three Installation

    Unlike AT/ISA boards, but like Micro Channel boards, EISA boards do not normally require hardware jumpers. Ensure that you have the correct version of the AHA-1740A/1742A/1744 for your sys- tem. The AHA-1740A/1742A support the more common single-ended SCSI interface. The AHA-1744 supports the differential interface, more common on SCSI peripherals on minicomputers.

  • Page 38: System Configuration Background For Standard Mode

    SCSI hard disk. The AHA-1740A/1742A/1744 BIOS fully supports the extended partitioning ca- pabilities of DOS for up to two drives. Adaptec supplies a range of products based on the Advanced SCSI Programming Interface (ASPI) architecture that allow the sup- port of more than two physical or logical devices under DOS.

  • Page 39: Termination

    The details vary from vendor to vendor. Refer to the system documentation for details. The Adaptec AHA-1740A/1742A/1744 32-bit EISA bus-to-SCSI bus host adapter has been designed to operate as shipped in the majority of EISA class computers. A board direct from the factory is normally shipped with the ASW-C174 Configuration Utility.

  • Page 40: Scsi Parity

    SCSI devices generate parity, it is recommended that parity checking be turned on for all devices. Please note that generating parity and checking parity are two separate functions. The AHA-1740A/1742A/1744 configuration overlay can be used to enable/disable parity checking for each SCSI ID.
  • Page 41 SCSI cable should have terminators installed. On the AHA-1740 and AHA-1744, these are RN2, RN3, and RN4, located to the side of the internal SCSI connector. On the AHA-1740A and AHA-1742A, these are RN5, RN6, and RN7, located below the internal SCSI connector.
  • Page 42 7. Align the EISA bus connector on the bottom of the AHA-1740A/1742A/1744 to the open chassis slot with the slot cover removed. Ensure the external connector and bracket pass cleanly through the cutout in the rear wall. 8. Firmly plug the board into the slot. Use the screw from the corresponding expan- sion slot cover to secure the board bracket to the system frame.

  • Page 43: Checklist

    System Configuration When it is being installed in an EISA system, the AHA-1740A/1742A/1744 requires an EISA system configuration file. This may be part of the system software or may be supplied on a separate diskette. If it is separate, installation is easier if the contents of the separate diskette are copied onto the main bootable system configuration disk.
  • Page 44 1740A/1742A/1744, copy the contents of the ASW-C174 diskette with the AHA- 1740A/1742A/1744 configuration files to the boot floppy and run the configuration program. !adp0000.cfg for the AHA-1740 !adp0001.cfg for the AHA-1740A !adp0002.cfg for the AHA-1742A !adp0400.cfg for the AHA-1744 In addition, run adp0000.ovl for all boards. The configuration utility will usually allow selection among a number of options, including copying new con- figuration files.

  • Page 45: Mcs Configuration

    EISA-to-Fast SCSI Host Adapter MCS Configuration For configuration under MCS, select the slot in which the AHA-1740A/1742A/1744 is installed and press Enter. The screen will display the System Configuration De- tailed View. These settings should normally not be changed for Standard Mode opera- tion.
  • Page 46 When Enhanced Mode is selected, IRQ 11 is used by default. By default, if multiple AHA-1740 family host adapters are in the system in Enhanced Mode, all will use IRQ 11. For the MCS EISA Configuration Utility, this can be shown by selecting Change System Resources under the Edit pull down menu (or entering Ctrl- R) when the Host Adapter Interface Mode is highlighted.

  • Page 47: Standard Mode Scsi Configuration

    EISA-to-Fast SCSI Host Adapter Standard Mode SCSI Configuration The view for Standard Mode is a simple selection for those variables which apply to all SCSI peripherals connected. This is shown in Figure 3-5. Normally, the default of one device at SCSI ID 0 with normal default parameters is selected. System Global Host Adapter SCSI Configuration Options Enable Parity Checking...

  • Page 48: Enhanced Mode Scsi Configuration

    When this option is selected, use the cursor keys to move among the options shown in Figure 3-7. 3-12 System Configuration Detailed View Edit View Settings Configuration Settings for SCSI Devices 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 (MBs per second) Slot 4 AHA-1740A/1742A/1744 F1=Help Help...
  • Page 49 Maximum Synch Transfer Rate allows selection of the highest data transfer speed that the host adapter will attempt with that peripheral. The AHA-1740A/1742A/1744 support rates up to the Fast SCSI maximum of 10 MBytes/second. System Configuration Detailed View...

  • Page 50: Multiple Adapters Sharing Same Scsi Bus

    Int 11. When multiple 1740A/1742A/1744s are not attached to the same SCSI bus, then sharing of interrupts in Enhanced Mode is acceptable. 3-14 System Configuration Detailed View Edit View Settings Configuration Settings for SCSI Devices (MBs per second) Slot 4 AHA-1740A/1742A/1744 F1=Help Help...

  • Page 51: Phoenix Configuration

    J6 on the lower left of the board. If the jumper is removed, the board will return the identity of an AHA-1740A to any software inquiry command. This allows software to use the appropriate configuration file for the main part of the board, as described previously.

  • Page 52: Adl Operation

    At the DOS prompt, enter adl to bring up Adaptec’s AHA-1740/1744 download utility. The following will describe the procedures and the screen display. During the opera- tion, F1 can be pressed to display help messages and Esc to exit the current message box and the utility.

  • Page 53: Download Firmware (Aha-1740/1744 Only)

    Following is a description of each operation. Download Firmware (AHA-1740/1744 Only) The AHA-1740/1744 (not the AHA-1740A or AHA-1742A) have the unique flexibility of allowing firmware to be altered or upgraded while the board is installed in a sys- tem. This is done by using a utility on the ASW-C174 and either the firmware files supplied or new files supplied with ASW-M174.

  • Page 54: Firmware Information (Aha-1740/1744/1740A/1742A)

    After reading the host adapter information, press Esc to continue. Have this information available when contacting Adaptec with questions about firm- ware or upgrades. If multiple host adapters are installed, the Esc key can be used to select another host adapter from the List of Host Adapters menu.

  • Page 55: Hardware Functional Description

    For odd-byte starting addresses, the first transfer will be an 8-bit transfer, For odd-word starting address, the first transfer will be a 16-bit transfer. The SCSI port is controlled by the AIC-6251, and Adaptec SCSI protocol device for fast (10.0 MBytes/second transfers) which supports arbitration, selection, and reselec- tion with a minimum of processor intervention.

  • Page 56: I/O Port Interface Bit Definition

    WRITE: Reserved, do not write Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 AHA-1740A/1742A/1744 READ: Status Register Bit 7 Self Test in Progress (STST) Bit 6 Internal Diagnostic Failure (DIAGF) Bit 5 Mailbox Initialization Required (INIT)

  • Page 57: Control And Status Port

    (Host Adapter Status Port bit 4) are set when the reset processing is completed. This indicates that the AHA-1740A/1742A/1744 mailbox structure must be reinitial- ized and that no other operations are active on the host adapter. See the section on Reset Functions for a description of the overall reset structure.
  • Page 58 The host adapter must be reset by setting the Hard Reset bit (bit 7 of the Control Port) to clear the error. If the AHA-1740A/1742A/1744 again detects an error, troubleshooting procedures must be performed to identify and correct the er- ror condition.

  • Page 59: Command/Data Out And Data In Port

    EISA-to-Fast SCSI Host Adapter Hardware Functional Description Bit 2 - Data In Port Full (DF) The host uses the DF bit to synchronize transfers of data from the host adapter to the host. When the DF bit is set to one, the host adapter has placed a byte in the Data In Port for the host to remove and process.

  • Page 60: Interrupt Flag Port

    This bit, when one, indicates that the interrupt to the host has been established. The interrupting condition is identified in bits 0 to 3. Bit 6 - Reserved Returned as zero. Bit 5 - Reserved Returned as zero. Bit 4 - Reserved Returned as zero. AHA-1740A/1742A/1744...
  • Page 61 EISA-to-Fast SCSI Host Adapter Hardware Functional Description 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 interrupt signal will also be set. The host adapter supports SCSI Soft Reset (see Section 4.3).

  • Page 62: Reset Functions

    In addition to the RESET signal, the setting of the HRST bit (bit 7 of the Host Adapter Control Port) will force a hardware reset to the AHA-1740A/1742A/1744. Regardless of the source, a Hard Re- set forces the following actions on the AHA-1740A/1742A/1744.

  • Page 63: Scsi Reset Operations

    RESET signal or by the setting of the HRST bit. This reset is described in the Hard Reset Operations section. The SCSI Reset condition may be invoked by the AHA-1740A/1742A/1744 as part of the recovery mechanism for a bus phase error. Bus phase errors may include detec- tion of an invalid information transfer phase or detection of an impossible phase se- quence (Command Phase after a Data Phase in the same command).

  • Page 64: Scsi Hard Reset Option

    For certain types of systems that frequently do back-up or check point their transactions, that reinitialize quickly and easily, or that infrequently do resets, the Hard Reset option is appropriate. The AHA-1740A/1742A/1744 responds to a SCSI Reset condition by executing only the Soft Reset option, but it notifies the host when- ever a SCSI Reset condition has been established by causing an interrupt to the host.

  • Page 65: Expansion Board Id Registers

    The expansion board identifier registers are always available for access on the bus by the host system. They are used to transfer basic information on the identity of the board and its revision level from the AHA-1740A/1742A/1744 to the host. Host ID 0 (HID0, zC80, R) HID0 is the first byte of the expansion board ID.

  • Page 66: Board Configuration Registers

    Three, ADL Utility. It is written by the local processor and read by the system processor. RESDRV, HARDST or SOFTRST has no effect. The revision code for the AHA-1740/1744 is 00h, the AHA-1740A is 01h and the AHA-1742A is 02h. Board Configuration Registers These registers are used by the host process to define parameters on the board neces- sary for normal operation.
  • Page 67 EISA-to-Fast SCSI Host Adapter I/O Port Address (PORTADDR, zCC0, W/R) PORTADDR selects the base address for the I/O port interface. It is compared with the system address every cycle. If a match occurs, data will either be driven or sam- pled on the bus.
  • Page 68 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1100-1111 4-14 BIOS Address Table BIOS Address (hex) Not used Not used C8000 CC000 D0000 D4000 D8000 DC000 E0000 E4000 E8000 EC000 Not used AHA-1740A/1742A/1744...
  • Page 69 EISA-to-Fast SCSI Host Adapter 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 high true or low true. When high true, the interrupt is a two state signal and acts like an edge triggered interrupt, and may not be shared with another board.
  • Page 70 0 1 1 0 0 1 1 1 1000-1111 Bus Definition (BUSDEF, zCC4, W/R) This register allows the configuration of certain EISA bus features supported by the AHA-1740A/1742A/1744. Definition Reserved DMA Channel for Standard Mode Bit 3 BUSON These bits are written in order to set the time that the AHA-1740 stays on the bus when preempted by another device.

  • Page 71: Reserved Registers

    EISA-to-Fast SCSI Host Adapter Reserved Registers The following registers are reserved for future use. Reserved 0 (RESV0, zCC5, W/R) Reserved 1 (RESV1, zCC6, W/R) Reserved 2 (RESV2, zCC7, W/R) I/O Port Register Standard Mode (Group 1) The I/O Control Standard Mode (Group 1) registers form the primary communication channel between the system and the adapter for Standard Mode operation.
  • Page 72 CMD/DAT (Base + 1) with a command or parameter. This bit is polled by the local processor to determine if a byte is ready. It is cleared when the local processor reads the LCMDDAT register. (0) 4-18 AHA-1740A/1742A/1744...
  • Page 73 EISA-to-Fast SCSI Host Adapter Definition HAVAIL Information is Available to the system. When this bit is one, the local pro- cessor has loaded CMD/DAT (Base + 1) with data. It is cleared when the system reads CMD/DAT. This bit is also read by the local processor. (0) Reserved.

  • Page 74: I/O Port Register Enhanced Mode (Group 2)

    This process repeats until the transfer is complete. In response to a reset, if the host adapter passes diagnostics, then a value of 00H will be loaded in MBOXIN0. ATTN will also be read to clear the Busy bit. If the host 4-20 AHA-1740A/1742A/1744...

  • Page 75: Mailbox Registers

    EISA-to-Fast SCSI Host Adapter adapter fails diagnostics, then the local processor will load the value appropriate for the failure in MBOXIN0, according to the following list, and read ATTN to clear the busy bit. Reset Codes No Error Microprocessor ROM Test failure RAM test failure Power Protection device error Microprocessor internal peripheral test failure...
  • Page 76 5 = CCB completed with success after retry 7 = Adapter hardware failure A = Immediate command completed with success C = CCB completed with error D = Asynchronous event notification E = Immediate command completed with error Target ID SCSI ID of command 4-22 AHA-1740A/1742A/1744...

  • Page 77: Diskette Registers

    EISA-to-Fast SCSI Host Adapter Enhanced Mode (Group 2) Status (G2STAT, zCD7, R) Definition Reserved Mailbox out empty Set to one by firmware when it is done with the mailbox out. Cleared by software writing to any mailbox out location. Interrupt pending Reflects the state of the EISA interrupt line from the Enhanced Mode (Group 2) interrupt before the enable/disable logic.

  • Page 78: Diskette Controller Registers (Read/Write 3F4 And 3F5)

    Because of this multibyte interchange of information between the diskette controller and the proces- sor, each command can be considered to consist of three phases: 4-24 AHA-1740A/1742A/1744...

  • Page 79: Digital Input Register (Read 3F7)

    EISA-to-Fast SCSI Host Adapter Command Phase: The processor issues a sequence of write commands to the diskette controller that direct the controller to perform a specific operation. Execution Phase: The diskette controller performs the specified operation. Result Phase: After completion of the operation, status and other housekeep- ing information is made available to the processor through a sequence of read operations from the data register.

  • Page 80: Firmware Download (Aha-1740/1744 Only)

    Firmware Download (AHA-1740/1744 Only) The AHA-1740A/1742A permanently stores both Standard and Enhanced Mode firm- ware in an EPROM. A microcode upgrade consists of replacing that EPROM with an- other, and is seldom required. Please contact Adaptec for further information.

  • Page 81: Hardware Configuration Requirements

    EISA-to-Fast SCSI Host Adapter Hardware Configuration Requirements The following host adapter configuration options must be defined prior to setting the card enable bit in register zC84: The BIOS location must be set to an address which does not conflict with other system resources.

  • Page 82: Bios Driver Needs

    Enhanced Mode Firmware Description. FlagWord 1 Options Disable Status Block (bit 14) is supported. Setting this bit will disable the writing of the termination status block if no error occurs. All other bits should be set to zero. 4-28 AHA-1740A/1742A/1744...

  • Page 83: Configuration Byte Description And Defaults

    EISA-to-Fast SCSI Host Adapter Refer to Appendix D, EISA Free-Form Data for the initial SCSI subsystem data structure. Configuration Byte Description and Defaults The following describes the SCSI device configuration byte format. Firmware default values are also given. These defaults are used by the firmware to interface with the various targets in the event that no Initialize SCSI Subsystem command has been re- ceived by the host adapter.
  • Page 84 EISA INT 15h call. The name of the function type for this data is stored by the configuration utility at offset 23h. This type string must be the eight- character ASCII string SCSIDEVS. Additional information on the function configura- tion information data block is given in the EISA specification. 4-30 AHA-1740A/1742A/1744...
  • Page 85 EISA-to-Fast SCSI Host Adapter Function Configuration Information Data Block for SCSI Subsystem Data Byte Offset Description Function Information Byte B6 = 1 to indicate free from data Type and Subtype ASCII string "SCSIDEVS" Length of the following data block ASCII string "AHA-174x" 7C-7Fh Reserved SCSI device 0 byte 0...

  • Page 87: Host Adapter Command Overview

    Standard Mode Firmware Description Host Adapter Command Overview Standard Mode is the mode in which the AHA-1740A/1742A/1744 can operate in or- der to run existing software for earlier Bus Master host adapters. In Standard Mode, the AHA-1740A/1742A/1744 supports two types of commands: SCSI and adapter com- mands.

  • Page 88: No Operation (Operation Code 00)

    Mailbox Out entries and the same number of Mailbox In entries will be assigned beginning at the Mailbox ad- dress. The total number of bytes reserved for the mailbox area will be eight times the AHA-1740A/1742A/1744...

  • Page 89: Start Scsi Command (Operation Code 02)

    Start PC AT BIOS Command (Operation Code 03) This command is used by the Adaptec BIOS to communicate with the host adapter firmware. The command is not available for use by programs other than the Adaptec BIOS.

  • Page 90: Enable Mailbox Out Available Interrupt (Operation Code 05)

    This value indicates an ASCII value from 0-9, that indicates the first digit of the firmware base code revision installed in the AHA-1740A/1742A/1744. Firmware Revision Level (Second byte) This value indicates an ASCII value from 0-9, that indicates the second digit of the firmware base code revision installed in the AHA-1740A/1742A/1744.

  • Page 91: Set Selection Time Out (Operation Code 06)

    Set Bus On Time (Operation Code 07) This command is not used by the AHA-1740A/1742A/1744 but is supported in order to be compatible with software written for earlier host adapters, such as the AHA- 1542B.

  • Page 92: Set Bus Off Time (Operation Code 08)

    Set Bus Off Time (Operation Code 08) This command is not used by the AHA-1740A/1742A/1744 but is supported in order to be compatible with software written for earlier host adapters, such as the AHA- 1542B. This command sets the time that the host adapter will spend off the bus during a data transfer.

  • Page 93: Return Installed Devices (Operation Code 0A)

    AT Bus Transfer Speed 80-FFh Due to the internal differences between the AHA-1740A/1742A/1744 and earlier host adapters, the data is not actually used but is saved and returned in the Return Setup Data command. The command is accepted only for compatibility.

  • Page 94: Return Configuration Data (Operation Code 0B)

    The DMA arbitration priority, the Interrupt channel, and the SCSI ID of the adapter are returned by this command. The three bytes of information are returned in the fol- lowing format: Byte Description DMA Arbitration Priority AHA-1740A/1742A/1744 Bit 7 LU 7 Installed Bit 6 LU 6 Installed Bit 5...

  • Page 95: Enable Target Mode Command (Operation Code 0C)

    LU will be treated as installed. If the bit is zero, the LU will be treated as not installed. If the AHA-1740A/1742A/1744 does not have the Target Mode feature installed, the host adapter will indicate an invalid host adapter command. If an attempt is made to...

  • Page 96: Return Setup Data (Operation Code 0D)

    SCSI selection time out. Most reset operations, including Soft Reset, Hard Reset, and Power-On Reset will return the AHA-1740A/1742A/1744 Target Mode to the dis- abled state. SCSI resets, generated either by the host or by other SCSI devices, will not change the previously established enabled or disabled state of Target Mode.
  • Page 97 EISA-to-Fast SCSI Host Adapter Byte Description Bus Off Time Number of Mailboxes Mailbox Address (MSB) Mailbox Address Mailbox Address (LSB) 08-0F Synchronous Transfer Agreements Returns information about the synchronous negotiation with Target 0. The byte will be 00H for the address of the host adapter.

  • Page 98: Initialize Scsi Subsystem (Operation Code 10)

    Byte 1 Buffer area address Byte 2 Buffer area address, Least significant byte 5-12 AHA-1740A/1742A/1744 Meaning Each bit corresponds to a SCSI device, e.g., bit 0 corresponds to the device at SCSI address 0. When set to one, the host adapter will prevent the SCSI device from disconnecting.

  • Page 99: Read Adapter Channel 2 Buffer (Operation Code 1B)

    EISA-to-Fast SCSI Host Adapter Read Adapter Channel 2 Buffer (Operation Code 1B) After receiving this command, the host adapter expects three outbound information bytes to be transferred which point to an area of 64 bytes in system RAM. The area pointed to will be used as a buffer to receive 64 bytes of information transferred from the host adapter’s channel 2 buffer to the host’s memory using the host adapter’s DMA circuitry.

  • Page 100: Echo Command Data (Operation Code 1F)

    Returned echo value Adapter Diagnostic (Operation Code 20) Unlike other Adaptec host adapters, this command does not cause the host adapter to perform its internal self-diagnostic. A host adapter Hard Reset is not executed, nor is a SCSI bus reset. The host adapter need not be reinitialized after this command be- fore resuming normal operation.

  • Page 101: Mailbox Out Definition

    Initialization command was set to four. The base address is the address specified by the Mailbox Address field. The Adaptec BIOS initializes the AT DMA controller to accommodate Bus Master DMA. If the host adapter BIOS is removed or disabled, the host DMA controller must be initialized, via software, for Bus Master DMA operation.
  • Page 102 In Target Mode, one CCB may be presented for each unique combination of LUN, In- itiator, and direction. If a second CCB to the same LUN and initiator with the same direction bit is sent to the AHA-1740A/1742A/1744, the CCB will be returned with a host status of 19h, Duplicate CCB Received.

  • Page 103: Mailbox In Definition

    EISA-to-Fast SCSI Host Adapter host adapter will not change the MBOA interrupt bit and will continue to scan for other stored MBO entries. 3. If interrupts other than the Mailbox Out Available interrupt are pending, the host adapter will wait for the pending interrupts to be cleared before setting the Mail- box Out Available Interrupt.
  • Page 104 Byte Definition MBI Status This byte specifies the state of the MBI entry. Initiator and LUN 5-18 AHA-1740A/1742A/1744 Value Meaning Mailbox In is free CCB completed without error. CCB pointer indicates location of successfully completed CCB. CCB aborted by host. CCB pointer indicates location of CCB that was aborted.
  • Page 105 EISA-to-Fast SCSI Host Adapter Byte Definition Data Length The CCB Required Mailbox In entries are only generated when a command has been received by the host adapter in Target Mode. For the CCB Required Mailbox In en- tries, byte 0 takes on a distinctive value of 10h, indicating the MBI entry is filled and the MBI entry is being presented to request a CCB appropriate to service a SCSI transaction for which no CCB was available.

  • Page 106: Command Block Definition

    Operation Code Address and Direction Control SCSI Command Length Request Sense Allocation Length/Disable Auto Sense Data Length (Byte 4 most significant) 5-20 AHA-1740A/1742A/1744 Note Value Meaning SCSI Initiator command Target Mode command SCSI Initiator command with Scatter/Gather SCSI Initiator command,...
  • Page 107 EISA-to-Fast SCSI Host Adapter Byte Description Data Pointer (Byte 7 most significant) 10-12 Link Pointer (Byte 10 most significant) Command Linking Identifier Host Adapter Status (HASTAT) Target Device Status (TARSTAT) 16-17 Reserved (00) 18-n SCSI Command Descriptor Block (Length specified by byte 2) Reserved for Request Sense information bytes (Length of reserved space in...
  • Page 108 18+m The bytes of the CCB are defined further below: Byte 0: Command Control Block Operation Codes The AHA-1740A/1742A/1744 supports six CCB operation codes. The valid command values are shown below: SCSI Initiator Command Control Block SCSI Target Command Control Block...
  • Page 109 EISA-to-Fast SCSI Host Adapter Standard Mode Firmware Description AHA-1740A/1742A/1744. Operation codes 00h and 03h differ only in the updating of Bytes 4, 5, and 6, following completion of the command. If the operation code value is 01h, the CCB is intended to service a Send or Receive command sent to the host adapter as a target from another initiator.
  • Page 110 The SCSI specification indicates that a Request Sense command must be exe- cuted before any other command is executed in order for the host initiator to be sure of obtaining the error information. Since the AHA-1740A/1742A/1744 host adapter has the capability of queuing commands for execution, the host adapter itself must take charge of generating the Request Sense command.
  • Page 111 Command Descriptor Block generated by the host adapter. If an operation that treats the AHA-1740A/1742A/1744 as a Target Mode device fails and presents a check condition status byte, the Initiator should return a Request Sense command.
  • Page 112 More than one CCB was received to service data transfer between the same target LUN and initiator SCSI ID in the same direction. Invalid CCB or Segment List Parameter A segment list with a zero length segment or invalid segment list boundaries was received. A CCB parameter was invalid. 5-26 AHA-1740A/1742A/1744...
  • Page 113 CCBs, the CDB provided from the initiator is returned to the host in this space. Byte 18+n - 18+n+m : Allocated for Sense Data If a check status condition is detected by the AHA-1740A/1742A/1744 as it completes an operation on the SCSI bus, the host adapter automatically executes a Request Sense command with the data length specified by request sense allocation length.

  • Page 114: Scatter/Gather List Definition

    The direction of transfer with respect to the data area and the checking of the length of the data transfer to the data area are both managed by the AHA-1740A/1742A/1744 according to the requirements of the particular mode and control bit set-up.

  • Page 115: Description Of Operation

    Disconnection and reconnection on the bus are automatically taken care of by the AHA-1740A/1742A/1744. As the host adapter starts the SCSI operation, it will first determine if the addressed target/LUN is busy. If the target/LUN is busy, the command will be placed in the task queue to be tried again later.

  • Page 116: Execution Of Target Mode Operations With A Prepared Ccb

    CCB was already finished nor- mally and returned. The AHA-1740A/1742A/1744 scans the MBOs in a round-robin fashion. This is to en- sure that all of the mailboxes will be scanned with equal probability. A host can mini- mize the AHA-1740A/1742A/1744 MBO scan time by using MBOs sequentially.

  • Page 117: Execution Of Target Mode Operations Without A Prepared Ccb

    The DMA circuitry must be set to a special state to allow the Bus Master operation of the AHA-1740A/1742A/1744 to operate correctly. This state is normally established by the BIOS during initialization so that no other activity is required. If a DMA chan-...

  • Page 118: Interrupt Initialization

    The mask register is a read/write register, and only the bit of inter- est should be cleared. The port address is A1h, and bit definitions follow: 5-32 AHA-1740A/1742A/1744 DMA Controller Port Software Interrupt Vector Location (hex) Int 71...
  • Page 119 EISA-to-Fast SCSI Host Adapter Interrupt Mask Bit Definition (Port Address A1h) Standard Mode Firmware Description Interrupt Int 8 Int 9 Int 10 Int 11 Int 12 Int 13 Int 14 Int 15 5-33...

  • Page 121: Introduction

    Block (ECB) in memory. The host then stores the pointer to the ECB in the Mailbox Out, provided that bit 2 of the SCD7 Status register (MBO empty) is true. Due to the speed with which the AHA-1740A/1742A/1744 services the mailbox, the MBO will al- most always be empty.
  • Page 122 Clear EISA Interrupt bit in the control register zCD5. Multitasking is achieved by setting up multiple commands through the mailbox be- fore the first has been completed. The microcode maintains control of up to 64 com- mands executing simultaneously in the host adapter. AHA-1740A/1742A/1744 SCSI ID SCSI ID...

  • Page 123: Control Block

    EISA-to-Fast SCSI Host Adapter Control Block The control block is a 48-byte structure created and maintained in shared memory by software in the system unit. It is used to convey requests to the host adapter. Data or Scatter/Gather List Pointer Data or Scatter/Gather List Length CDB Length CDB Byte 1...

  • Page 124: Command Word

    Flag Word 1 Flag word 1 is a 16-bit structured field used to specify execution parameters for this control block. Fields that are empty are reserved and should be set to zero. AHA-1740A/1742A/1744 Operations Code...
  • Page 125 EISA-to-Fast SCSI Host Adapter Flag Name and Function Chain No Error The Chain No Error flag (bit 0) indicates whether control block chaining is enabled. If this bit is set to one, chaining is enabled. Upon successful completion of the control block, the host adapter will fetch the next control pointed to by the chain address.

  • Page 126: Flag Word 2

    Target SCSI commands. For all other commands, setting this flag to one will result in a specification check. Flag Word 2 Flag word 2 is a 16-bit structured field used to specify execution parameters for this control block. Fields that are empty are reserved and should be set to zero. AHA-1740A/1742A/1744...
  • Page 127 EISA-to-Fast SCSI Host Adapter Flag Name and Function Logical Unit Number This field (bits 2-0) specifies the logical unit number of the target for which the com- mand is to be executed. Tagged Queuing This flag (bit 3) indicates whether tagged queuing should be implemented for this control block.
  • Page 128 (Write operation). If a Data In phase is detected, the host adapter will abort the command and report an invalid phase error. The invalid phase error will not be reported if no data phase is detected. AHA-1740A/1742A/1744...
  • Page 129 EISA-to-Fast SCSI Host Adapter Flag Name and Function Suppress Transfer to Host Memory This flag (bit 10) indicates whether an incoming data transfer is to be suppressed. This flag will be ignored if the Data Transfer flag (bit 8) is set to zero. If this bit is set to one, the host adapter will accept data from the target, but will not transfer it to host memory.

  • Page 130: Data Or Scatter/Gather List Pointer

    SCSI command. The number of 8-byte segments is limited to 128 (one pointer and one length), but the host adapter will only store a maximum of 17 segments in its internal memory at a time. The diagram below describes the struc- ture of the Scatter/Gather list. 6-10 AHA-1740A/1742A/1744...

  • Page 131: Data Or Scatter/Gather List Length

    EISA-to-Fast SCSI Host Adapter 1F 1E 1D 1C 1B 1A 19 18 17 16 15 14 13 12 11 10 The data lengths must be less than 4 MBytes and the total length of the transfer must be less than 16 MBytes. Data or Scatter/Gather List Length This 32-bit field contains the length in bytes (least significant byte first) of the data transfer.

  • Page 132: Chain Address

    The host adapter will then verify the result with the value specified in this field. If the two values do not compare, an error will be reported. This option is currently available only for the Download Firmware command. 6-12 AHA-1740A/1742A/1744 Note...

  • Page 133: Scsi Command Descriptor Block

    EISA-to-Fast SCSI Host Adapter SCSI Command Descriptor Block This 6-, 10-, or 12-byte field contains the actual CDB to be sent to the target during command phase. Status Block The status block is a 32-byte structure created in shared memory by software in the system unit.

  • Page 134: Status Word

    If this bit is set to one, the host adapter has rejected the control block because its internal storage area is full. No action is taken on the control block. The host should reissue the control block after an outstanding control block completes or after an appropriate time delay. 6-14 AHA-1740A/1742A/1744...
  • Page 135 EISA-to-Fast SCSI Host Adapter Flag Name and Function Specification Check The Specification Check flag (bit 4) indicates that the host adapter detected an error in the control block. If this bit is set to one, the host adapter has rejected the control block due to an error in one of the control block’s fields (i.e., unsupported operation code).
  • Page 136 Resume command for the associated target. It is also cleared by resetting the host adapter or by issuing a Bus Device Reset to the associated target. This flag is set to one for every control block completed while the extended contingent allegiance condition exists. 6-16 AHA-1740A/1742A/1744...

  • Page 137: Host Adapter Status

    EISA-to-Fast SCSI Host Adapter Host Adapter Status This 8-bit field contains additional error information pertaining to the host adapter or SCSI subsystem in general. This field is valid when the Command Done flag is set to zero and one of the following flags is set to one: Specification Check, Initialization Required, or Major Error/Exception.

  • Page 138: Residual Byte Count

    This field is valid only if the Data Underrun or Data Overrun flag (Status Word, bits 1 and 5, respectively) is set to one. 6-18 AHA-1740A/1742A/1744...

  • Page 139: Additional Status Length

    EISA-to-Fast SCSI Host Adapter 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 that was most recently used to transfer data. If Scatter/Gather was not enabled for the associated control block, then this field con- tains the address specified in the data pointer field of the control block.
  • Page 140 (if enabled) will interrupt the host by writ- ing to the Enhanced Mode (Group 2) Interrupt Status register. The Mailbox In regis- ters will contain the address of the completed control block. Following are the control block commands described in alphabetical order. 6-20 AHA-1740A/1742A/1744 SCSI ID...

  • Page 141: Download Firmware

    EISA-to-Fast SCSI Host Adapter Download Firmware Options Fields that are empty are reserved and should be set to zero. This command causes the host adapter to overwrite its program memory with data supplied by the host. The host adapter will, if enabled, perform a checksum on the data after it is written to its internal RAM, and compare the checksum to the value stored in the control block.

  • Page 142: Supported Options

    Flag Word 1 - Disable Interrupt (bit 7) and Disable Status Block (bit 14) are sup- ported. All other flags should be zero. Flag Word 2 - The Calculate Checksum option (bit 11) should be used. All other flags should be zero. 6-22 AHA-1740A/1742A/1744...

  • Page 143: Initialize Scsi Subsystem

    EISA-to-Fast SCSI Host Adapter Initialize SCSI Subsystem Pointer to Initialization Configuration Data Length of Initialization Configuration Data Fields that are empty are reserved and should be set to zero. This command allows the host to place a copy of the configuration information per- taining to the SCSI subsystem (stored in system CMOS RAM) into the host adapter’s internal RAM.
  • Page 144 SCSI Device 6 (LSB)** SCSI Device 7 (LSB)** SCSI Device 8 (LSB) SCSI Device 9 (LSB) SCSI Device 10 (LSB) SCSI Device 11 (LSB) SCSI Device 12 (LSB) SCSI Device 13 (LSB) SCSI Device 14 (LSB) SCSI Device 15 (LSB) AHA-1740A/1742A/1744 Byte Offset...
  • Page 145 EISA-to-Fast SCSI Host Adapter All bits not defined above are ignored by the host adapter and may be set to either 0 or 1. The Disconnection Enable bit (least significant byte, bit 2) determines whether the host adapter will allow the specified target to disconnect during a SCSI operation. If the enable bit is one, then disconnection is allowed for that device.

  • Page 146: Initiator Scsi Command

    (Flag Word 2, bit 11). 6-26 Flag Word 1 Flag Word 2 Status Block Pointer Chain Address Sense Information Pointer Sense Length CDB Byte 0 CDB Byte 2 CDB Byte 4 CDB Byte 6 CDB Byte 8 CDB Byte 10 AHA-1740A/1742A/1744 Byte Offset...

  • Page 147: No Operation

    EISA-to-Fast SCSI Host Adapter No Operation Options Fields that are empty are reserved and should be set to zero. If the SCSI ID specified in the Attention register specifies the SCSI address of the host adapter, then this command is intended for diagnostic purposes to test whether the transfer of control blocks and their associated interrupts are working properly.
  • Page 148 Flag Word 1 - Chain No Error (bit 0), Disable Interrupt (bit 7) and Disable Status Block (bit 14) are supported. All other flags should be zero. Flag Word 2 - Logical Unit Number (bits 2-0) are supported. All other flags should be zero. 6-28 AHA-1740A/1742A/1744...

  • Page 149: Read Host Adapter Inquiry Data

    EISA-to-Fast SCSI Host Adapter Read Host Adapter Inquiry Data Options Destination Pointer of inquiry data Fields that are empty are reserved and should be set to zero. This command can be used to obtain release information and revision level of the host adapter’s firmware.
  • Page 150 Disable Status Block (bit 14) are supported. All other flags should be zero. Flag Word 2 - None of the options in Flag Word 2 are supported by this command. The information is written into host memory in the following format. 6-30 AHA-1740A/1742A/1744...
  • Page 151 EISA-to-Fast SCSI Host Adapter No. of LUNs Flags Reserved for Information on SSCI Peripherals Enhanced Mode Firmware Description SCSI Device Type SCSI Support Level Additional Lng No. of CBs Vendor Verification Product Identification Firmware Type Firmware Revision Level Release Date Release Time Firmware Checksum Reserved...
  • Page 152 The actual LUNs supported start at LUN 0 (e.g., if this byte contains a 3, then LUN 0, 1 and 2 are enabled.) Byte 6 indicates the number of control blocks the host adapter can store internally be- fore responding with a queue full status. The flags byte contains the following information. 6-32 AHA-1740A/1742A/1744...
  • Page 153 (e.g., Adaptec). The product identification field contains eight bytes of ASCII data identifying the product name of the host adapter (e.g., AHA-1740A/1742A). The firmware type field contains eight bytes of ASCII data indicating whether the firmware is a standard product or a special version (e.g., Enhanced).

  • Page 154: Read Sense Information

    After completion of this command, the host adapter and the target will release contingent allegiance and resume operation for any queued commands. If extended 6-34 Flag Word 1 Flag Word 2 Status Block Pointer Sense Information Pointer Sense Length AHA-1740A/1742A/1744 Byte Offset...
  • Page 155 EISA-to-Fast SCSI Host Adapter 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 extended contingent allegiance. Supported Options Flag Word 1 - Suppress Error on Underrun (bit 10) and Disable Status Block (bit 14) are supported.

  • Page 156: Run Diagnostic Test

    Any value of these bits not defined below may result in a specification check. 6-36 Flag Word 1 Write FIFO Data Pointer Read FIFO Data Pointer Test FIFO Data Length Status Block Pointer AHA-1740A/1742A/1744 Byte Offset...
  • Page 157 EISA-to-Fast SCSI Host Adapter Value Meaning Self-Test The host adapter performs a subset to its self-diagnostic routines that it normally performs at power-up. The two data pointer fields and the data length field is ignored. Test FIFO The host adapter will transfer data from the address in the write FIFO data pointer field (least significant byte first) to its internal FIFO.

  • Page 158: Target Scsi Command

    SCSI device. The SCSI address of the initiator is supplied in bits 3-0 of the attention register. The logical unit number of the host adapter is supplied in bits 2-0 of Flag Word 2. 6-38 Flag Word 1 Flag Word 2 Status Block Pointer Sense Information Pointer Sense Length AHA-1740A/1742A/1744 Byte Offset...

  • Page 159: Aborting Control Block Commands

    EISA-to-Fast SCSI Host Adapter 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 length of the transfer may not be known. Disable Status Block (bit 14) should also be used with care since the status block will return information regarding the actual command received.

  • Page 160: Control Block Is Queued For Operation

    The abort operation will have no affect. There is no interrupt associated with the abort operation. Its sole purpose is to pre- maturely terminate any control block queued or in progress. 6-40 AHA-1740A/1742A/1744 Note Note...

  • Page 161: Asynchronous Event Notification

    EISA-to-Fast SCSI Host Adapter Asynchronous Event Notification An asynchronous event occurs when the host adapter detects an unexpected condi- tion on the SCSI subsystem. Asynchronous Event Conditions A SCSI bus reset has occurred The host adapter was selected by another initiator The host adapter notifies the host of an asynchronous event via an interrupt.

  • Page 162: Host Adapter Selected By Another Initiator

    Instead of a control block address, a 32-bit immediate command is stored into the Mailbox Out registers, least significant byte first. The Attention register is then stored with the following value: 6-42 CDB Byte 2 CDB Byte 3 AHA-1740A/1742A/1744 CDB Byte 4...

  • Page 163: Reset

    EISA-to-Fast SCSI Host Adapter The SCSI ID specifies either the SCSI address of a particular target, or the SCSI ad- dress of the host adapter. The host adapter’s ID can be found in bits 3-0 of the SCSI Definition register. When the Attention register is written to, the host adapter is interrupted.
  • Page 164 Asynchronous Event Notification interrupt. Any commands that were outstanding when the SCSI Bus Reset occurred and any commands re- ceived between the reset and the host acknowledgment of the Asynchronous Event Notification interrupt will be returned with error status. The status 6-44 AHA-1740A/1742A/1744...

  • Page 165: Reset Host Adapter

    EISA-to-Fast SCSI Host Adapter returned will reflect that the command was aborted by the host adapter (error code = 05). Any commands received after the acknowledgment of the Asynchro- nous Event Notification interrupt will be operated on normally. Reset Host Adapter If the Attention register contains the SCSI ID of the host adapter, then this com- mand is intended to reset the SCSI subsystem to a known state.

  • Page 166: Resume

    Adapter Reset Option flag is set to zero, the SCSI bus will be reset by the host adapter as part of its reinitialization. There will be no notification of the SCSI reset since it is implied by the Soft Reset. 6-46 AHA-1740A/1742A/1744 Byte Offset...

  • Page 167: Reset Initiated By The Host Adapter

    EISA-to-Fast SCSI Host Adapter Reset Initiated by the Host Adapter The host adapter will reset the bus if it encounters an error on a SCSI operation that it cannot recover from. Some examples include: the target goes to an invalid bus phase, the host adapter cannot force the target to go bus free when attempting to abort a command, or the host adapter cannot send a bus device reset message.
  • Page 168 Asynchronous Event Notification interrupt will be returned with error status. The status returned will reflect that the command was aborted by the host adapt- er (error code: 05). Any commands received after the acknowledgment of the asyn- chronous event notification will be will be operated on normally. 6-48 AHA-1740A/1742A/1744...

  • Page 169: Introduction

    SCSI devices other than CCS disk drives, or if support for more than two disk drives is required under DOS, the Adaptec DOS Driver, ASW-1410 must be used. The BIOS provides a very simple single-threaded capability that does not make use of the Mail- box Interface used by more sophisticated programs.

  • Page 170: No Standard Hard Disks Installed

    No Standard Hard Disks Installed In this case, two SCSI drives can be supported by the AHA-1740A/1742A/1744 BIOS. SCSI target 0 Logical Unit Number (LUN) 0 is designated as drive 0 (drive C). Either SCSI target 0 LUN 1 or SCSI target 1 LUN 0 may be designated as drive 1 (drive D).
  • Page 171 EISA-to-Fast SCSI Host Adapter BIOS base address in the boards setup registers. In the case where the board is not functioning properly, the BIOS will display the message: Unable to initialize SCSI host adapter! and the BIOS will fail initialization. The failure will be flagged to the system via the BP register so that the system BIOS can halt system initialization until the user strikes a key (F1 on most systems).

  • Page 172: Other Changes

    The AHA-1740A/1742A BIOS will revector Interrupt 13h so that all calls for disk I/O can be filtered by the AHA-1740A/1742A BIOS. Requests for non-SCSI drives are passed on to the original Int 13h vector which is stored in shadow RAM.

  • Page 173: Interrupt 13H Interface Functionality

    EISA-to-Fast SCSI Host Adapter AHA-1740A/1742A CMOS configuration so the desired boot drive is the first drive found by the system. Interrupt 13h Interface Functionality Disk I/O requests are passed from the operating system to the BIOS through soft- ware interrupt 13h. CPU registers are used to pass a function code as well as the as- sociated parameters for the function.

  • Page 174: Bios Command Return Codes

    (it may not be contiguous). The AHA-1740A/1742A BIOS will fully support the VDS specification so that 386 memory management programs will be able to run without a driver as long as they are VDS compliant.

  • Page 175: Hardware Bios Commands

    2Ah - Unit Attention, Mode Select Change Undefined error occurred: A SCSI ASC other than those listed was returned by the target. Write Fault: Not returned by AHA-1740A/1742A BIOS Sense Operation Failed: An error occurred issuing the SCSI request sense command to the target.
  • Page 176 A SCSI Read Capacity command is used to determine the maximum logical block of the selected SCSI drive. This information is returned to the host along with the DASD type of the target which will always be 03h for hard disk. AHA-1740A/1742A/1744 Function Status of Operation...

  • Page 177: Int 15H Functionality

    An invalid command error is returned for any of these function codes. Int 15h Functionality After issuing an I/O command to the host adapter, the AHA-1740A/1742A BIOS will make use of the Int 15 Device Busy (function 90h) to inform the operating system that the BIOS is about to wait for a device.

  • Page 178: Multiple Adapter Support

    CC000, DC000, EC000, and D0000, the BIOSs will install in the order of CC000, D0000, DC000, and finally EC000. In Standard Mode, you can install a maximum of four AHA-1740A/1742A/1744 host adapter cards. The limiting factor is the number of available ISA DMA channels (5, 6, 7, and 0).

  • Page 179: Aha-1740A/1742A/1744 Timing Diagram

    Appendix A Memory Cycle Timing Diagram AHA-1740A/1742A/1744 Timing Diagram...

  • Page 180: Parameter Table

    SLBURST* held from BCLK rising Data delay from BCLK rising (write) Data hold from BCLK rising (write) Data held after BCLK rising (read) Data setup to BCLK rising (read) MSTR16* delay from BCLK rising (downshift) nanoseconds AHA-1740A/1742A/1744 Minimum Maximum 45.0 35.0 15.0 25.0 15.0...

  • Page 181: Internal Connector Pin Assignments

    Appendix B Connector Pinout Internal Connector Pin Assignments AHA-1740A/1742A (Single-Ended) Signal Name Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Open Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Signal Name -DB(0)
  • Page 182 +DB(7) +DB(P) DIFFSENS Reserved Term Power (Fused) Reserved +ATN Ground +BSY +ACK +RST +MSG +SEL +C/D +REQ +I/O Ground AHA-1740A/1742A/1744 Signal Name Ground -DB(0) -DB(1) -DB(2) -DB(3) -DB(4) -DB(5) -DB(6) -DB(7) -DB(P) Ground Reserved Term Power (Fused) Reserved -ATN Ground...

  • Page 183: External Connector Pin Assignments

    EISA-to-Fast SCSI Host Adapter External Connector Pin Assignments AHA-1740A/1742A (Single-Ended) Signal Name Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Open Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Ground Connector Pinout Signal Name...
  • Page 184 +DB(7) +DB(P) DIFFSENS Reserved Term Power (Fused) Reserved +ATN Ground +BSY +ACK +RST +MSG +SEL +C/D +REQ +I/O Ground AHA-1740A/1742A/1744 Signal Name Ground -DB(0) -DB(1) -DB(2) -DB(3) -DB(4) -DB(5) -DB(6) -DB(7) -DB(P) Ground Reserved Term Power (Fused) Reserved -ATN Ground...

  • Page 185: System Register Reference

    Appendix C Register Reference System Register Reference Expansion Board IDs Definition Host ID 0 Host ID 1 Host ID 2 Expansion Board Control BMIC Registers Group 1 Definition I/O Port Address BIOS Address Interrupt Definition SCSI Definition Bus Definition Floppy Definition Reserved 1 Reserved 2 Mailbox Out Byte 0...
  • Page 186 Local Reserved 2 Local Mailbox Out Byte 0 Local Mailbox Out Byte 1 Local Mailbox Out Byte 2 Local Mailbox Out Byte 3 Local Mailbox In Byte 0 Local Mailbox In Byte 1 AHA-1740A/1742A/1744 Signal EISA Slot MBOXIN2 zCDA MBOXIN3 zCDB...
  • Page 187 EISA-to-Fast SCSI Host Adapter Definition Local Mailbox In Byte 2 Local Mailbox In Byte 3 Local Group 2 Control Local Group 2 Status Local Group 2 Interrupt Status Local Group 2 Attention Local Expansion Board Control Local Expansion Board Control Local Data Register Local Index Register Local Control/Status...

  • Page 189: Scsi Subsystem Data Structure

    Appendix D EISA Free-Form Data SCSI Subsystem Data Structure SCSI Device Byte Reserved 16-47 Bit Definitions Bit 7 - Allow removable media in BIOS disk scan Bit 6 - More than 1 LUN supported Bit 5 - Parity check enable Bit 4 - Send start command Bit 3 - Synchronous negotiation enable Bit 2 - Disconnection enable...
  • Page 191 STOCK NO.: 510208-00 Rev.A GM 3/92 691 south milpitas blvd. milpitas, ca 95035 (408)945-8600 Printed in Singapore...

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