V P - 3 2 2 1 0 W S D C A P E L L A QUANTUM NO MORE PRODUCED Native| Translation ------+-----+-----+----- Form 3.5"/SLIMLINE Cylinders | | | Capacity form/unform 2216/ 2824 MB Heads 8| | | Seek time / track 9.0/ 1.0 ms Sector/track | | | Controller SCSI2 DI/WI/FAST Precompensation Cache/Buffer 1024 KB SEGMENTED Landing Zone Data transfer rate 6.900 MB/S int Bytes/Sector 512 20.000 MB/S ext SYNC Recording method RLL 1/7 operating | non-operating -------------+-------------- Supply voltage 5/12 V Temperature *C 5 55 | -40 66 Power: sleep W Humidity % 10 90 | 8 95 standby W Altitude km | idle 6.3 W Shock g 10 | seek 7.5 W Rotation RPM 5400 read/write W Acoustic dBA 35 spin-up W ECC Bit ON THE FLY,REED SOLOMON MTBF h 800000 Warranty Month 60 Lift/Lock/Park YES Certificates ********************************************************************** L A Y O U T ********************************************************************** QUANTUM VP31110/32210 CAPELLA PRODUCT MANUAL 81-108335-01 4/1995 +---------------------------------------------------------+ | VP31110/32210S +--+ |XX | +--+TERMPWR |XXI | HEADER PINS |XXN | |XXT | |XXE | |XXR J1 | |XXF | |XXA | |XXC | |XXE |+-+ |XX || | |XX || |Option |XX || |J3 | |+-+ |XX Power | |XX J2 +---------------------------------------------------------+ +---------------------------------------------------------+ | VP31110/32210W/WD +--+ |XXI | +--+TERMPWR |XXN | HEADER PINS |XXT | |XXE | |XXR | |XXF J1 | |XXA | |XXC | |XXE | |+-+ |+-+ || |Option || | || | || |Option || | || |J3 |+-+ |+-+ |XX Power | |XX J2 +---------------------------------------------------------+ +---------------------------------------------------------+ | VP31110/32210R | | | | | | |XX | |XX | |XX J1 | |XX RAID | |XX | |XX | |XX | |XX | * FAULT LED |XX | |XX | | | | | * BUSY LED | +---------------------------------------------------------+ 50-pin SCSI Connector (8-bit) ----------------------------- +------------------------------------+ | Back View | | | +------------J1----------------J2----+ |+------------ ------------++-------+| ||oooooooooooooooooooooooo1||O O O O|| ||oooooooooooooooooooooooo2|| || |+-------------------------++-------+| +-----------SCSI-------------Power---+ + + +------------------------------------+ | Front View (Bezel End) | | | | | +------------------------------------+ +--+----------+----------------------+ | |ooo oooooo20 | + |oooooooooo| + +1---------J3 Option Connector 68-pin SCSI Connector (16-bit) ------------------------------ +--------------------------------------------------+ | Back View | | | +------------J1------------------------------J2----+ |+-------------------------+ +---Option--++-------+| |34ooooooooooooooooooooooo1| |o o o o o 1||O O O O|| |68ooooooooooooooooooooooo35 12 o o o o o|| || |+-------------------------+ +-----------++-------+| +-----------SCSI---------------------------Power---+ + + +--------------------------------------------------+ | Front View (Bezel End) | | | | Fault LED | +--+-----------------------------------------------+ +--+---+-------+-----------------------------------+ | | |o ooooo|Secondary Option | + | |ooooooo|Connector + | +1--J3--+ Busy LED 80-pin SCSI Connector (Raid) ---------------------------- +--------------------------------------------------+ | Back View | | | +--------------------------------------------------+ | +-----------------------------------------+ | | | J1 | | +-----------------------------------------+ | +----------Combination-Connector-------------------+ + + ********************************************************************** J U M P E R S ********************************************************************** QUANTUM VP31110/32210W/WD CAPELLA PRODUCT MANUAL 81-108335-01 4/95 Jumper Setting ============== TERMPWR (Terminator Power) -------------------------- Generally, the host is the only device on the SCSI bus required to provide TERMPWR for the bus. To ensure that there is a sufficient level of power along the entire SCSI bus, Digital Equipment Corporation recommends that all devices on the SCSI bus supply TERMPWR (if they are capable). SCSI devices are protected by a diode or similar semiconductor to prevent back flow of the terminator power when more than one device supplies this power. NOTE Model VP31110R/32210R drives do not supply TERMPWR. The SCA connector does not accommadate this feature. SCSI Connector XXXXXXXXXXXXXXXXXX +------------------- | | | o X | Configure the following model drives to provide TERMPWR by installing the jumper as shown: VP31110/32210-W/WD SCSI Bus Termination -------------------- Both ends of the SCSI bus cable must be terminated. One end is terminated at the host. The other end must be terminated by the last SCSI device on the SCSI bus. NOTE Model VP31110/32210WD/R drives cannot provide bus termination. When the Model VP31110/31110W and VP32210/32210W drive is the last device on the SCSI bus, configure the drive to provide bus termination. VP31110W/32210W Bus Termination ------------------------------- Configure Model VP31110W/32210W drives to provide bus termination by installing the three termination resistor pack SIPs on the PCBA. Note the orientation of pin 1 of the resistor pack (shaded or marked area of SIP). SCSI Power XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXX +------------------------------------------+ | xxxxxxxxxxxxxxx1 | | xxxxxxxxxxxxxxx1 | | xxxxxxxxxxxxxxx1 | VP31110W/32210W | +-+ +---------+ | | |:|TERMPWR Termination SIPs | +-+Header | SCSI ID (Address) Selection --------------------------- Each device on the SCSI bus must have a unique SCSI ID number assigned to it. ID number for VP31110/32210 models (8-bit SCSI) range from 0 through 7. For W/WD models (16-bit SCSI), the numbers range from 0 through 15. SCSI ID numbers for R models range from 0 through 7 for 8-bit configurations and from 0 through 15 for 16-bit configurations. Configure the SCSI ID of VP31110/32210-W/WD models by installing jumper across the indicated Option connector pins. For R versions, provide the proper open or ground signal input to the referenced pins of the drive's 80-pin RAID connector. SCSI ID - VP31110/32210W/WD 16-bit ---------------------------------- +---+--+----+ |o o o o o 1| |o o o o o o| Option Connector 12--+--+----+ SCSI ID - 16-bit drives ----------------------- +----------+-------------------------------+ | SCSI ID | Jumper Location | | | PINS | | | 7-8 | 5-6 | 3-4 | 1-2 | +----------+-------+-------+-------+-------+ | 0 | OPEN | OPEN | OPEN | OPEN | +----------+-------+-------+-------+-------+ | 1 | OPEN | OPEN | OPEN | CLOSED| +----------+-------+-------+-------+-------+ | 2 | OPEN | OPEN | CLOSED| OPEN | +----------+-------+-------+-------+-------+ | 3 | OPEN | OPEN | CLOSED| CLOSED| +----------+-------+-------+-------+-------+ | 4 | OPEN | CLOSED| OPEN | OPEN | +----------+-------+-------+-------+-------+ | 5 | OPEN | CLOSED| OPEN | CLOSED| +----------+-------+-------+-------+-------+ | 6 | OPEN | CLOSED| CLOSED| OPEN | +----------+-------+-------+-------+-------+ | 7 | OPEN | CLOSED| CLOSED| CLOSED| +----------+-------+-------+-------+-------+ | 8 | CLOSED| OPEN | OPEN | OPEN | +----------+-------+-------+-------+-------+ | 9 | CLOSED| OPEN | OPEN | CLOSED| +----------+-------+-------+-------+-------+ | 10 | CLOSED| OPEN | CLOSED| OPEN | +----------+-------+-------+-------+-------+ | 11 | CLOSED| OPEN | CLOSED| CLOSED| +----------+-------+-------+-------+-------+ | 12 | CLOSED| CLOSED| OPEN | OPEN | +----------+-------+-------+-------+-------+ | 13 | CLOSED| CLOSED| OPEN | CLOSED| +----------+-------+-------+-------+-------+ | 14 | CLOSED| CLOSED| CLOSED| OPEN | +----------+-------+-------+-------+-------+ | 15 | CLOSED| CLOSED| CLOSED| CLOSED| +----------+-------+-------+-------+-------+ The following optional features can be configured according to your system requirements. These features are model-dependent and include: - Spindle Synchronization - Write protection (not supported on R Models) - Spin delay Spindle Synchronization ----------------------- Capella disk drives support synchronized spindle operation. Master or slave synchronized operation is set through a SCSI Mode Select Page. When the drive operates as a Master, it generates a spindle synchronization reference signal (SPINDLE_SYNC_REF L). When operating as a slave, the drive synchronizes its spindle according to the SPINDLE_SYNC_REF L input reference. The drive always maintains local speed regulation when no reference signal is applied. NOTE The reference signal must originate from drives with the same electronics modules. Fo example, connect Model VP31110 drive only with another VP31110 or VP32210 drive. Do not connect the SPINDLE_SYNC_REF L signal to that of any other series disk drive or the drive may malfunction. When connecting multiple drives together for spindle synchronization, be sure to use proper cabling techniques to avoid ground loop problems. For Model VP31110/32210 drives (except SCA), pin 10 (Option connector) is provided as an alternate SPINDL_SYNC_REL L connection to facilitate installations where a 10-pin header is used to connect several remote features. Pin 19 is provided to permit the use of a 2- pin connector for SPINDL_SYNC_REF L connections. The ground return is pin 20, although pins 2, 4, or 6 can be used for the ground return. +--- LOGIC_GND L +2-----------14 |o o o o o o| |o o o o o o o| Secondary Option Connector +1------------+ +--- SPINDL_SYNC_REF L Write Protection 16-bit Drives, except SCA ------------------------------------------ +2-----------14 |o o X o o o| |o o o X o o o| Secondary Option Connector +1------------+ To write protect the drive, install a jumper across Secondary Option connector pins 7 and 8. To disable write protection, remove the jumper. Spin Up Power On ----------------- Atlas drives have three Spin-Up on Power On modes: - Option 1 Spin up occurs immediately when power is applied - Option 2 Drive spins up occurs after a predetermined delay following power on. The delay is equal to a user-specified multiplier, multiplied by one plus the numerical SCSI ID of the drive. - Option 3 Drive spin up is controlled by the START STOP UNIT command. +2-----------14 |X o o o o o| |X o o o o o o| Secondary Option Connector +1------------+ For Option 1, immediate spin up power on, install the jumper across pins 1 and 2 of the Secondary Option connector. For Option 2, spin up after a delay, install the jumper across pins 1 and 2 of the Secondary Option connector. Set delay parameters in the MODE SELECT command, Quantum (Vendor) Special Function Control Page. For Option 3, spin up controlled by the START STOP UNIT command, remove the jumper (if present) from across pins 1 and 2 of the Option connector. Remote Features Capella Series drives support the following remote features, which can be configured at the drive's Option connector or RAID backplane: - Remote SCSI ID selection - Remote LED status display Remote SCSI ID Selection ------------------------ The SCSI ID can be set remotely from an external (remote) switch or control panel. For Model VP31110/31110W/31110WD drives and Model VP 32210/32210W/32210WD drives, this is accomplished using the Option connector. For Model VP31110R/32210R drives, the outputs of remote or external ID switches at the RAID system backplane take the place of jumpers. Configure drives for remote ID selection by removing the SCSI ID jumpers (if present) from the SCSI ID pins. Then connect the leads from the external selection switch to the referenced pins. Observe the following guidelines while doing so. - ID bit 0, at Pin 1, is the Least Significant bit. - SCSI ID bits 0, 1, 2, and 3 are active LOW signals. That is, the bit is a 1 if the corresponding remote switch is closed to ground. - For 16-Bit drives, use pin 10 for the common ground return of all four ID bits. Do not use pins 2, 4, 6, or 8 as a common ground return. Pin 2, 4, 6, and 8 are reserved as outputs or future outputs. +---+--+----+ |o o O O O O| |o * o o o o| Option Connector 12--+--+----+ * LOGIC_GND L (Pin 10) O SCSI ID <0>, <1>, <2>, <3> L (Pins 1, 3, 5, 7) Remote LED Status Display ------------------------- Busy and Fault status for Model VP31110/32210-W/WD drives can be monitored remotely by connecting a remote Busy and a remote Fault display LED to the drive's Option connector or secondary Option connector. R Model drives provide the output, ACTIVITY LED OUT, which can be used to drive a user-supplied remote LED. Busy status is monitored remotely by connecting the cathode side of the remote Fault LED to the FLT_OUT L pin. The anode side of the LED connects to the +5 VDC OUT pin. Fault status can be monitored remotely by connecting the cathode side of the remote Fault LED of the BSY_OUT L pin. The anode side of the LED connects to +5 VDC OUT pin. +---- FLT_OUT L +2-----------14 |o o o o o o| |o o o o o o o| Secondary Option Connector +1------------+ | +---- +5 VDC OUT +------ BUSY_OUT L NOTE As an alternative connection the remote Busy LED and the remote Fault LED can be connected to the drive using the 12-pin Option connector. However, shunt jumpers to configure the SCSI ID cannot be used when remote LED's are connected to the 12-pin Option connector. In this case, you must run a cable from the Option connector to a remote location and set up the SCSI IDs using switches or remote jumpers. + +5 VDC OUT | +-----------+ |* o o o o 1| |o o * o o *| 12----------+ | +-- FLT_OUT L | +----BSY_OUT L ********************************************************************** I N S T A L L ********************************************************************** QUANTUM VP31110/32210 CAPELLA PRODUCT MANUAL 81-108335-01 4/1995 Notes on installation ===================== Drive mounting -------------- horizontally vertically +-----------------+ +--+ +--+ +------------------+ | | | +-----+ +-----+ | | | | | | | | | | | |+----------------+| +-+-----------------+-+ | | | | | | || || +---------------------+ | | | | | | || || | | | | | | || || | | | | | | || || +---------------------+ | +-----+ +-----+ | || || +-+-----------------+-+ +--+ +--+ || || | | || || | | || || +-----------------+ || || ++----------------++ You can mount the disk drive in any position. LR models mount in RAID storage subsystems. The drive (with bezel) attaches to the system bay and accept #6-32 screws. Screws should not exceed 0.25 inch (6.25 millimeters) in length, otherwise damage to the PCB may result. Combination Connector - 8-bit ------------------------------ +-----------------+-----------------------------------------------+ | Part Number | Vendor | +-----------------+-----------------------------------------------+ | 12-41254-01 | Quantum | +-----------------+-----------------------------------------------+ | 87711-502 | Berg Electronics (formerly Dupont Electronics)| +-----------------+-----------------------------------------------+ Includes 0.1-in pitch, 50-pin SCSI connector and 4-pin power connector. Combination Connector - 16-bit ------------------------------- +-----------------+-----------------------------------------------+ | Part Number | Vendor | +-----------------+-----------------------------------------------+ | 12-43123-01 | Quantum | +-----------------+-----------------------------------------------+ | 87360-0003 | Molex | +-----------------+-----------------------------------------------+ Includes 68-pin SCSI connector, 4-pin power connector, and a 2-mm pitch, 12-pin (2x6) Option connector. Option Connector - 8-bit ------------------------ +-----------------+-----------------------------------------------+ | Part Number | Vendor | +-----------------+-----------------------------------------------+ | 12-36484-08 | Quantum | +-----------------+-----------------------------------------------+ | 954339-01-10-15 | 3M | +-----------------+-----------------------------------------------+ | P92-300-204-6 | AMP, Inc. | +-----------------+-----------------------------------------------+ | 87049-2085 | Molex, Inc. | +-----------------+-----------------------------------------------+ A 2-mm pitch, 19-pin (2x10) keyed (missing pin) connector Secondary Option Connector - 16-bit ----------------------------------- +-----------------+-----------------------------------------------+ | Part Number | Vendor | +-----------------+-----------------------------------------------+ | 12-36484-09 | Quantum | +-----------------+-----------------------------------------------+ | P93-300-204-7 | AMP | +-----------------+-----------------------------------------------+ | 954339-01-07-15 | 3M | +-----------------+-----------------------------------------------+ A 2-mm pitch, 13-pin (2x7) keyed (missing pin) connector Shunt Jumper - All Models ------------------------- +-----------------+-----------------------------------------------+ | Part Number | Vendor | +-----------------+-----------------------------------------------+ | 12-36482-01 | Quantum | +-----------------+-----------------------------------------------+ | 86730-001 | Berg Electronics (formerly Dupont Electronics)| +-----------------+-----------------------------------------------+ | LPC-SPG | Honda | +-----------------+-----------------------------------------------+ A 2-mm pitch shunt for configuring termination characteristics RAID Connector - SCA Models --------------------------- +-----------------+-----------------------------------------------+ | Part Number | Vendor | +-----------------+-----------------------------------------------+ | 12-41319-01 | Quantum | +-----------------+-----------------------------------------------+ | SSC80-D01 | Specialty Electronics | +-----------------+-----------------------------------------------+ Champ 0.050 inch Series I 80-position plug DC Power and pin connector assignments -------------------------------------- +------------+ pin 1 +12 VDC | 4 3 2 1 | pin 2 +12 Volts Return GROUND +------------+ pin 3 + 5 Volts Return GROUND pin 4 + 5 VDC Mounting brackets may be required when installing the drive in a 5.25-inch form factor bay. We recommended using brackets supplied by Quantum Corporation to mount the drive. Otherwise, the drive's isolation characteristics could be compromised. A bracket kit including four screws is available from the Quantum Corp. The part number is 70-30695-01. CAUTION The placement of the drive in the computer system must permit sufficient air-flow to maintain drive environment temperature within 41*CF to 131*F (+5*C to +55*C) and maintain component surface temperatures below the maximums. CAUTION Screw-length must not exceed 0.25-inch (6.25 millimeters); or the drive may be damaged (#6-32). ********************************************************************** F E A T U R E S ********************************************************************** QUANTUM VP31110/32210 CAPELLA PRODUCT MANUAL 81-108335-01 4/1995 Product Description ------------------- The VP31110/VP32210 disk drives are 3.5-inch, low-profile, high- capacity, high-performance drives with formatted capacity of 1,103 MB or 2,206 MB. The drives feature magneto-resistive (MR) read heads which greatly increase the amount of storage available on a disk surface and significantly improves the data integrity of the read/ write process. Drive performance reaches an average seek time of 7.9 ms, an achievable interface transfer rate up to 20MB/s, and an instanttaneous media transfer rate of 46.5 to 70.9 Mb/s. The drives use a 512KB segmented-cache buffer for improved caching performance. The drives provide data integrity by using parity check- ing, end-to-end error detection codes (EDC) and a 198-bit error correction code (ECC) on each data block stored. Caching ------- Cache is RAM used as intermediate storage between the initiator and the disk. System performance is improved by placing data in RAM, which is a higher performance memory, avoiding a disk access. Since most reads and writes are sequential, caching data beyond that actually requested yields increased throughput for most applications. Segmented Buffer ---------------- The drive features a 512 KB segmented buffer that maximizes the cache hit rate for sequential read streams. The cache is organized as separate track line segments. Each track line segment can hold data from one complete track on the media, temporarily assuming the identity of that corresponding track for all input/output functions. A segment can be thought of as intermediate storage in the form of a ring buffer maintained in the drive's on-board RAM. When servicing a READ Command, the drive temporarily stores data in the ring buffer. When servicing a WRITE Command, the drive fetches data from the host and temporarily stores it in a ring buffer as well. Several SCSI DASD options assume the presence of this intermediate storage. As soon as a head arrives at a track containing requested data, the drive starts to read into the assigned cache track at the first byte after completion of the seek. The drive then reads the following bytes in that track and even the preceing bytes, until the cache track line contains a complete copy of all data stored in the corresponding media track. (If interrupted by a new SCSI command, the drive stores the appropriate pointers and completes this reading sequence after completing the interrupt.) Write Caching ------------- The drive can also do write caching. With write caching, writes are considered complete when the data are in the drive's data cache, before they written on the disk. The drive is able to combine writes from multiple commands to deliver higher performance. It is recommended that the system integrator provide a non-interruptable source of power for optimal write caching reliability. Disconnect/Reconnect -------------------- System throughput is improved by disconnecting the drive from the initiator during time-consuming physical position operations to free the SCSI bus for other I/O processes. The Disconnect/Reconnect function is controlled by the ASABET processor, greatly reducing the time required for the operation. After the drive has determined that there will be a delay, it disconnects from the SCSI bus by sending a SAVE DATA POINTER and DISCONNECT message to enter the BUS FREE phase. When the drive is ready to resume data transfer, it arbitrates for the SCSI bus. Upon winning arbitration, it reconnects to the initiator an dsends an IDENTIFY message via the MESSAGE IN phase. This revives the I_T_L nexus so the initiator can retrieve the correct set of data pointers for the I/O process. The initiator restores the active pointers to their most recent saved values, and the drive continues to finish the original I/O process. The enhanced capabilities of the ASABET processor increases throughput. A forced disconnect is implemented through the Mode Select Command (15h) Disconnect/Reconnect page (02h). Media Error Protection ---------------------- To verify that data reads are correct, an Error Correction Code (ECC) is calculated and stored with each block of data written. The code is recalculated on readout and used to correct errors that are detected. The larger the ECC, the greater its correction capability. The Capella drives use a 198-bit ECC. This size ECC allows correction of up to a 73-bit error burst per data sector. In comparison, competitive drives may use only a 56- or 88-bit ECC with attendant poorer performance. In addition, an error burst of 25 bits can be corrected "on the fly" (by hardware) with no delay processing. Transfer Error Protection ------------------------- Although ECC protects against faults in the media, the entire data path must also be protected. The drive uses end-to-end error detection code (EDC) to protect data from errors that may be intro- duced by the connecting busses, the disk controller chip, the data cache, or the SCSI interface. The EDC is computed from the data and the LBA as it arrives from the SCSI bus (after SCSI bus parity is checked). The EDC is written to disk along with the data. When a block is read, the EDC is recalculated and compared against the EDC that was written on disk. This operation protects against transfer errors introduced anywhere on the internal data path. Embedded Servo System --------------------- Embedded servo information is written in a spoke configuration, 72 times on every track, on every disk surface. The spokes (or headers) consist of quadrature analog pattern and digital address data. The digital portion of the spoke data are read and used to locate the desired track, spoke, and head number. The quadrature analog signal portion is detected and used by a servo feedback control loop to precisely position the head on the track center. Spindle Synchronization ----------------------- Spindle Synchronization is the process of causing the disk assemblies in several disk drives to rotate to the same address location at the same time. Synchronization is used in RAID (redundant arrays of independent devices) mass storage systems, allowing a set of disk drives to function as one drive. To accomplish this, sector 0, track 0 of each drive must be under the read/write heads at exactly the same time. With spindle synchronization, all the drives are locked to the same relative position. If all the drives are synchronized exactly, the time used to access one drive results in the next drive passing the correct position. This problem is resolved by using an offset that is the sum of the transmission delays of the interconnecting bus cable, data transfer times, and the rotational latency of the drives. Knowing how long it takes to set up an I/O operation and transfer data to a drive, the SCSI controller can send the data to one drive and, while that data is being transferred, set up the I/O transfer to the next one. When the current transfer is complete, the controller is ready to transfer the next, and so on. Spindle Synchronization is controlled by the Rigid Disk Geometry and (Vendor) Special Function Control pages of the MODE SELECT command. Special Functions ----------------- Quantum has incorporated a number of unique options into the drive. The (Vendor) Special Function Control page is used to control these options. The options include: - Spin Delay - delays the spin-up of the drive to reduce startup load of system power. - Initiate Synchronous Data Transfer Negotiation - a toggle-type parameter that allows the initiator to move between asynchronous and synchrounous modes of data transfer. - Slow Cable - adds an additional delay to REQ/ACK for very long bus cables. - Force Disconnect - the drive can be forced to disconnect from the SCSI bus after a SCSI Command is received in order to reduce on-bus time. Force Disconnect works only when a typical, error-free command is received. - Spindle Sync Check Interval - specifies the time, in minutes, of the interval between spindle synchronization status checks. - Stagger Spin Delay - specifies the time in 100 ms increments of the delay the drive uses in the spin-up delay formula, allowing a series of drives to be spin up at staggered time intervals. Banded recording ---------------- In banded recording, the disk is divided into multiple bands or partitions (also called notches or bit-zoned areas). Starting at inner band, each next outer band has a hihger recording frequency. The VP31110/32210 drives have 11 bands. The use of multiple-frequency recording greatly increases the capacity of the drive. Diagnostics ----------- The drive has extensive diagnostic capabilities, including those described below: power-up self-test, periodic self-adjustments, and host diagnostics. Power-Up Self-Test ------------------ The disk drive performs a self-diagnostic test immediately at power up. If the drive fails its self-diagnostic tests, it will report sense information but will not spin up. The drive diagnostics test the following: - Drive master microprocessor - RAM and ROM chips - Buffer memory - Gate array chips - Read/write encoding circuits - Basic servo functions - SCSI interface control circuits Following a selection time after power-on, the disk drive is able to respond with appropriate status and sense data to the TEST UNIT READY, INQUIRY, and REQUEST SENSE commands.