Adaptec 1744, AHA-1740A, 1742A user manual System Caching Description

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adaptec	AHA-1740A/1742A/1744

System Caching Description

The AHA-1740A/1742A/1744 fully supports operating systems caching to maximize overall system performance. Having RAM on the host adapter can actually decrease overall system perform- ance while adding cost. Operating systems such as Novell® Net- Ware, OS/2®, UNIX, XENIX, DOS and Windows™ have built-in cache and caching the same data in the operating system and on the host adapter can bog down system performance.

Overall system performance is increased by increasing the size of the operating system cache (i.e. add more RAM to the system motherboard), and by utilizing the advanced multithreading fea- tures of SCSI to minimize the mechanical limitations of SCSI peripherals (such as disk seek times by using zero latency reads).

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Contents User’s Manual Page User’s Manual Copyright Iii Page Table of Contents Adaptec Glossary Index List of Figures List of TablesPreface Conventions BoldPage South milpitas blvd. ∙ milpitas, ca 95035 ∙408945-8600 Overview General Product InformationAdaptec EISA-to-Fast Scsi Host Adapter Overview Installation Software AHA 1740A/1742A/1744 Program FilesBios Operation Modes AHA 1740A/1742A/1744 Operation ModesSystem Caching Description Product Specifications AHA-1740A/1742A/1744 Product Specifications∙ Technical Reference Manual ∙ Installation GuideAssociated Documentation Hardware Installation Unpacking and InspectionPreparation Scsi Terminators Scsi Device TerminationScsi Parity Scsi IDPhysical Installation in the System Adaptec Multiple Host Adapter Support Standard ModeEnhanced Mode Standard and Enhanced Modes Adaptec Download Utility Running the ADL ProgramHost Adapter Listing ADL Main Menu Download Firmware Download Firmware ScreenDownload Warning Message Screen Enhanced Mode Firmware Information Firmware InformationLow-Level Format Low-Level Format Device Selection ScreenLow-Level Format Options screen displays Low-Level Format Option Selection ScreenExiting the ADL Program Exiting the ADL ProgramPage Host Adapter Bios Operation Standard Mode OperationAdaptec Enhanced Mode Operation Enhanced Bios Boot MessageBoot Message With Error Detection Enabled Troubleshooting Determining Problems Using the LEDProblems Detected During Installation AHA 1740A/1742A/1744 LED Flash CodesEISA-to-Fast Scsi Host Adapter Troubleshooting Problems Booting the System from a Scsi Drive Problems Using a Scsi and a Standard Disk DriveProblems Using Two Scsi Drives Adaptec DOS 1 Gigabyte Limit Extended Translation Using DOSDisk Drives Over 1 Gigabyte Drives With Mixed Partitions When to Use Extended Translation With DOS Version 5 OnlyUsing Extended Translation Load ASW-1410 v3.0a Using FdiskQuestions and Answers About Extended Translation Adaptec Loading the I/O Operating Environment Software DOS/WindowsUnix Novell NetWareOS/2 Glossary Bus Device Reset Command Control BlockCommand Descriptor Block Asynchronous Event NotificationCommon Command Set ConfigurationDirect Memory Access Control MicroprocessorHost Enhanced ModeFirmware Host Adapter IBM PC-AT CompatibleIndustry Standard Architecture InitiatorMailbox Mailbox OutManager Multi-tasking OperationScatter/Gather Scsi DeviceSingle-Ended Single-Threaded OperationStandard Mode Synchronous Data TransferSynchronous Data Transfer Negotiation Tagged QueuingIndex AHA-1740A/1742A/1744 Index-2 Index-3 AHA-1740A/1742A/1744 Index-4