Seagate STT8000A manual Control circuits, Head design, Sensors and switches

Page 79

Theory of operations

Chapter 7

Control circuits

The control logic module shown in Figure 7-1 includes a buffer manager to handle data movement between the controller, the buffer, and the tape formatter. This module also includes logic to perform ECC and CRC generation and testing, WRITE/READ data formatting, head stepper control, and drive motor control.

The microprocessor directs all functions performed by the control logic. The instructions are read from a flash EEPROM, which can be updated with new firmware through a specially written tape cartridge.

The 512-KB DRAM data buffer allows the drive to maintain streaming when the host cannot provide data continuously at the tape streaming rate.

The write driver receives data from the write formatter and generates write current, causing data to be written on tape by the tape head.

The read channel amplifies and conditions the signal from the tape head and passes it back to the read formatter.

The head stepper and drive motor both receive current from the control logic to control the stepping of the head from track to track and to move the tape forward and back across the tape head.

Head design

The recording/playback head is a state-of-the art, thin-film design—a thin-film inductive write head paired with an advanced magneto-resistive read head. This head design provides the drive with exceptional performance and reliability. The material composition of the head also results in exceptional wear characteristics, resulting in stable performance throughout the life of the drive.

Flash EEPROM

Because the drive uses flash EEPROM (electronically erasable, programmable read-only memory), the drive firmware can be easily upgraded when new revisions of the firmware are released. The circuitry includes 128 KB of flash EEPROM.

You can load new firmware by using a specially encoded firmware upgrade cartridge.

Refer to chapter 4 for information about loading new firmware using a Seagate firmware upgrade cartridge.

Sensors and switches

A number of mechanical and optical sensors and switches are integrated in the drive design. The Cartridge In switch detects when a cartridge is fully loaded and positioned against the A-plane datum of the cartridge. The Unsafe switch senses

STT8000A Product Manual

Page 71

Image 79

Contents STT8000A Atapi Minicartridge Drive Product Manual Page FCC Notice Important Information About This Manual Table of Contents Atapi interface Tape format Glossary Acronyms and measurements Drive overview IntroductionSTT8000A internal drive without mounting brackets Features Minicartridge technology overview Typical system configurationsSoftware Flash EepromReferences Chapter Title Description About this manualPhysical specifications SpecificationsOverview STT8000A 3.5-Inch mount general dimensions Specification Measurement Power specificationsFeature Specification Performance specificationsEnvironmental requirements Specification Operational Non-operationalMean-Time-Between Failures ReliabilityMean-Time-To-Repair Tape capacities and formats Recommended tapesTUV & IEC-RHEINLAND Regulatory complianceHandling guidelines InstallationIntroduction Before you beginJumper block and jumper settings Setting jumpersAligning the drive in the computer Installing the driveMounting dimensions Mounting holes on internal drive without mounting brackets Pin Assignment Description Source ATA-2 Interface pin assignmentsREQ Chapter Installation Front panel LED Drive operation and maintenanceLoading and unloading cartridges Using Travan cartridgesTravan cartridge write-protect switch-locked position Setting the write-protect switchLoading revised firmware via Seagate firmware cartridge Caring for tape cartridges Care and maintenance of the drive and cartridgesCaring for the drive Capstan Tape Head Troubleshooting Chapter Atapi interface ATA-2 SignalsATA-2 Interface Abrt ATA registersBits Mnemonic Description Previous Cmd Int Reason Supported ATA CommandsFeature Number Set Feature Commands Atapi Identify Device A1h Atapi Packet Command A0h DSC Atapi interfaceErase command Bit Byte Inquiry commandLoad/Unload command Locate command Log Select command Log Sense command Following table presents the Error Counter Page layout Error Counter Page ReadFollowing table presents the Tape Capacity Page layout Tape Capacity Page CodeMode Select command Code Description Mode Sense commandMode Block Descriptor Mode Parameter HeaderMode Capabilities and Mechanical Status Mode Medium PartitionMode Tape Parameters Read command Following table describes the Read Position layout Read Position commandChapter Atapi Interface Request Sense command Following table describes the Request Sense layout Rewind command Space command Test Unit Ready command Write command Write Filemark command Write Buffer download microcode command Tape partitioning Tape formatTrack positions Track format Track numberingFrames General track layout Blocks Tape reference servo patternRandomization Write equalizationChapter Tape format Theory of operations Block diagramChassis Capstan drive motor assemblyMechanics Cartridge load mechanismControl circuits Sensors and switchesHead design Travan minicartridge Media-Travan minicartridgesGlossary Appendix a Glossary Glossary Appendix a Glossary Acronyms and abbreviations Acronyms and measurementsLSI Measure Meaning Units of measurementAppendix B Acronyms and Measurements