
S T 3 5 5 0 A           M E D A L I S T    SEAGATE
NO MORE PRODUCED                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 3.5"/SLIMLINE         Cylinders        | 1018|     |
Capacity form/unform   452/  550 MB        Heads           5|   14|     |
Seek time   / track  12.0/ 3.5 ms          Sector/track     |   62|     |
Controller           IDE / ATA2 FAST/ENHA  Precompensation
Cache/Buffer           256 KB LOOK-AHEAD   Landing Zone
Data transfer rate    3.500 MB/S int       Bytes/Sector      512
                     11.100 MB/S ext
Recording method     RLL 1/7                        operating  | non-operating
                                                  -------------+--------------
Supply voltage     5/12 V       Temperature *C         5 55    |    -40 70
Power: sleep              W     Humidity     %         8 80    |      5 95
       standby        0.9 W     Altitude    km    -0.305  3.048| -0.305 12.192
       idle           3.2 W     Shock        g         2       |     75
       seek           5.6 W     Rotation   RPM      4500
       read/write     5.4 W     Acoustic   dBA        34
       spin-up        7.0 W     ECC        Bit
                                MTBF         h     250000
                                Warranty Month        24
Lift/Lock/Park     YES          Certificates     CSA,FCC,UL478,VDE



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                        L   A   Y   O   U   T
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SEAGATE  ST3550A  DRIVE PRODUCT MANUAL 3612-001, REV.A

    +-------------------------------------------------------++-1
    |                                                       || |J5
    |                                                       |+-+
    |                                                       |XX J7
    |                                                       |
    |                                                       |XX
    |                                            I/O        |XX
    |                                            Connector  |XX J1
    |                                                       |XX
    |                                                       |XX
    +---+                                                   |XX
  J8 +-+|                                                   |XX
     | ||                                                   |XX1
     1-+|                                                   |
    +---+                                          +--+     |XX Power
    |                                              |++|     |XX J3
    +----------------------------------------------++++-----+
                                                    J6



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                      J   U   M   P   E   R   S
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SEAGATE  ST3550A  DRIVE PRODUCT MANUAL 36192-001, REV.A

 Jumper setting
 --------------
 x = Jumpers are set by factory


 J5  Master/slave and slave present jumper block
 -----------------------------------------------
     --+----+-- PCB
      3|o  x|1
      4|o  o|2
       +----+

      1- 2  OPEN   One drive only
 x    3- 4  OPEN

      1- 2  CLOSE  Drive is slave
      3- 4  OPEN

      1- 2  OPEN   Drive is master with slave present
      3- 4  CLOSE

 If only one drive is installed, do not install any jumper on the
 master/slave present jumper block.

 If there are two drives installed on the bus, one must be configured
 as a master and the other as a slave. No more than two drives can be
 connected on the AT bus.

 To configure the drive as a master with slave present, install a
 jumper on pins 3 and 4 only of the master/slave  and slave present
 jumper block.

 If both the master and the slave are ST3550A drives, you do not need
 to install a jumper on pins 3 and 4. This is because the master can
 detect the presense of the slave using the interface DASP-signal. If
 the drives in your application do not implement the DASP-signal,
 install the jumper on the master drive only.

 To configure the drive as a slave, install a jumper on pins 1 and 2
 only of the master/slave and slave present jumper block.


 J6  Factory test
 ----------------
 The pins on this jumper block are used for testing during the manu-
 facturing process; they are not for field use.


 J7  Mini power connector
 ------------------------
   --+---------+-- PCB
     | o  o  o |
     +---------+
       |  |  |
       |  |  +----  + 5 VDC
       |  +-------  +12 VDC
       +----------  Ground


 J8  Options jumper block
 ------------------------
     13 11  9  7  5  3  1
     +-------------------+
     |o  o  o  o  o     x|
     |o  o  o  o  o  o  o|
     +-------------------+
     12 11 10  8  6  4  2

  pin- 3   Removed for key
  pin- 8   Spindle clock I/O pin 28
  pin- 9   Clock ground
  pin-10   External spindle clock sync.
  pin-13   Remote LED -
  pin-14   Remote LED +

  Note: All other pins are reserved. Do not use them.


 J8   Remote LED connection
 --------------------------
 If you want to add a remote LED, attach a two-pin, 0.1-inch connector
 to pins 13 and 14 of the options jumper block.


 J8  Spindle synchronization
 ---------------------------
 The spindle clock signal (SPSYNC-) synchronizes the ratation of up to
 12 drives in a system. When two or more drives are connected to the
 host, the drives automatically configure themselves in either of two
 ways:

 - The spindle synchronization clock signal is generated by the host.
   The drives configure themselves as slaves and synchronize their
   spindles according to the host signal.

 - The spindle synchronization clock signal is generated by one of the
   drives. The master configures itself as the originator of the
   SPSYNC-signal; the other drives become slaves, or receivers of the
   SPSYNC-signal.

 The slave receives the signalto synchronize its spindle with the host
 or master and synchronizes its index with the SPSYNC-signal. Synchro-
 nization is achieved, and is indicated by the drive setting DRDY.
 (If a drive that was already synchronized loses synchronization, but
 continues to function, it does not clear DRDY.)

 There are three ways to enable spindle synchronization:

 - Enable pin 28 (SPSYNC-) of the AT interface connector by installing
   a jumper on pins 8 and 10 of the options jumper block.

 - Connect a twisted pair to pins 9 and 10 of the options jumper block
   to transmit and receive SPSYNC-.
   Use one strand of the twisted pair to connect pin 9 of the options
   jumper block of each drive. Use the other strand to connect pin 10
   of the options jumper block of each drive. The cable should not be
   longer than six feet (1.8 meters).

 The spindle clock uses a single-ended TTL, active low, 75Hz signal
 with a clock period of 13.34 msec   0.5% and a duty cycle of 0.5  sec
 minimum, 500  sec maximum. The spindle clock leading edge to index
 leading edge is 0   250  sev.


 J3   DC Power and pin connector assignments
 -------------------------------------------
    --+------------+-- PCB    pin 1    +12 VDC
      | 1  2  3  4 |          pin 2    +12 Volts Return
      +------------+          pin 3    + 5 Volts Return
                              pin 4    + 5 VDC



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                      I   N   S   T   A   L   L
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SEAGATE  ST3550A  DRIVE PRODUCT MANUAL 36192-001, REV.A

 Notes on installation
 =====================

 Drive mounting
 --------------
 You can mount the drive in any orientation. Follow the guidelines
 below appropriate to the set of mounting holes you elect to use:
 either bottom mounting holes or side mounting holes.

 Notes: Regardless of which set of holes you use, use only three
        mounting screws.

        For optimum performance, format the drvie in the same orien-
        tation as you mount it in the host system.

 Bottom mounting holes
 Use three 6-32 UNC screws in the 4 available bottom mounting holes.
 Do not insert the bottom mounting screws more than 0.20 inch (5.08mm
 6 turns) into the drive frame. If you use a screw that is too long,
 you could damage the drive.

 Side mounting holes
 Use three 6-32 UNC screws in three of the six available side mounting
 holes.
 Do not use all three mounting holes on the same side of the drive.
 Use one or both of the following: the side mounting hole near the
 power connector or the side mounting hole (on the other side of the
 drive) near the interface connector.
 Use at least one, but no more than two, of the other four side
 mounting holes.
 Do not insert side mounting screws more than 0.13 inch (3.3 mm,
 4 turns) into the drive frame. If you use a screw that is too long,
 you could  damage the drive.


 I/O cable and connector
 -----------------------
 The I/O connector is a 40-pin connector. The even pins are next to
 the edge of the printed circuit board; the odd pins are away from the
 printed circuit board. Pin 1 is near the 4-pin power connector.

 There is no pin 20 because that location is used as a key. The corre-
 sponding pin hole on the cable connector should be plugged to prevent
 the connector from being installed upside down. The I/O cable cannot
 be any longer than 18 inches (0.46 meters).

 2-Drive configuration
 ---------------------
 The drive can be daisy-chained with a second drive if the second
 drive meets the same interface specifications. In this configuration,
 one drive is designated as the master and the other as the slave.

 Shock and vibrations
 --------------------
 All shock and vibration specifications assume that the drive is moun-
 ted in an approved orientation with the input levels at the drive
 mounting screws.

 DC power
 --------
 Except during the write procedure, you can turn off and turn on power
 to the drive in any sequence without loss of data or damage to the
 drive. If you turn off the power during the write procedure, you may
 lose the data currently being written.
 All voltage tolerance of  5% must be maintained under all conditions,
 including ripple.

 Power management
 ----------------
 The drive implements intelligent power management by automatically
 changing power modes based on interface activity. Power management
 reduces the average power consumption considerably compared to a
 drive without this feature.

 Interface commands and interface-selectable parameters allow you to
 customize the power management configuration. Transitions between the
 Standby mode and the Idle mode (through the Spinup mode) are con-
 trolled by both the power management configuration and the interface
 demands. Transitions between the Idle mode, the Read/Write mode and
 the Seeking mode are controlled solely by interface requests.

 NOTE: If you install the ST3550A as a slave with a master drive that
       does not support power management (for example ST1239A drive),
       do not use power management commands on the ST3550A.

 SPINUP     The drive brings the spindle and discs up to operating
            speed. Power in this mode is defined as the average power
            during the first 10 seconds after starting spinup. This
            mode is entered from the Standby mode.
 SEEKING    The drive moves the actuator to position the read/write
            heads to a specific location on the disk surface in anti-
            cipation of a read/write operation. Read/write electronics
            are powered down and servo electronics are active. Power
            used during this mode is the average power measured while
            executing random seeks with a 2-revolution dwell between
            Seek commands.
 READ/WRITE The drive performs a read or write operation from or to
            the disk medium. Read/write electronics are active and the
            servo is in the track-following mode. This mode is entered
            from the Idle mode.
 IDLE       The drive spindle is up to speed and the heads are track-
            following. Some of the drive electronics are powered down.
            Commands that require media access return the drive to the
            Active mode with a 3-msec delay required to repower the
            drive's electronics. The drive responds to any command
            that does not require media access without leaving the
            IDLE mode. The status reported to the host is that the
            drive is ready.
 STANDBY    The drive spindle is stopped, the heads are parked in the
            landing zone, the actuator is latched, and some of the
            drive electronics are powered down. The drive reports to
            the host that it is in the Ready mode. The drive remains
            in the Standby mode to respond to commands that do not re-
            quire media access. The drive returns to the Active mode
            to respond to commands that require media access after a
            delay required to spin up the drive.

 FCC Verification
 ----------------
 This equipment has been tested with a Class B computing device and
 has been found to comply with Part 15 of the FCC rules. These limits
 are designed to provide reasonable protection against harmful inter-
 ference in residential installations. This equipment generates, uses,
 and can radiate radio frequency energy, and if not installed and
 used in accordance with the instructions, may cause harmful inter-
 ference to radio communications. There is no gurantee that interfer-
 ence will not occur in a particular installation.

 Caution: Any changes or mofifications to the equipment by the user
 not expressly approved by the grantee or or manufacturer could void
 the user's authority to operate such equipment.

 Note: This digital apparatus does not exceed the Class B limits for
 radio noise emission from computer equipment as set out in the radio
 interference regulations of the Canadian Department of Communica-
 tions.

 Handling and Static-Discharge Precautions
 -----------------------------------------
 After you unpack the drive, and before you install it in a system, be
 careful not to damage it through mishandling. Observe the following
 standard handling and static-discharge precautions:

 Use a ground wrist strap.

 Handle the drive by its edges. Do not put any pressure on the drive
 top cover. Do not touch the PC board.

 Always rest the drive on a padded surface until you mount it in the
 host system.

 Do not remove Seagate factory-installed labels from the drive or
 cover them with  additional labels. If you do, you void the warranty.
 Factory-installed labels contain information needed to service the
 drive.

 Thermal compensation
 --------------------
 The thermal compensation feature compensates for thermal-related
 position offset on the selected head. Thermal compensation is per-
 formed during start-up and ervery 2 minutes thereafter. This peri-
 odic compensation coincides with a host command service operation.
 Due to thermal compensation, the execution time of the last command
 increases by 100msec - 350 msec.

 Start/Stop time
 ---------------
 Within 20 seconds after DC power is applied, the drive is ready.
 Within 15 seconds after DC power is removed, the drive is stopped.

 Read/Write head auto-park
 -------------------------
 Upon power-down, the read/write heads automatically move to the
 shipping zone. The heads park inside the maximum data cylinder. When
 power is applied, the heads recalibrate to track 0.



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                      F   E   A   T   U   R   E  S
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SEAGATE  ST3550A  DRIVE PRODUCT MANUAL 36192-001, REV.A

 Format capacity
 ---------------
 You cannot low-level format the ST3550A drive.

 During manufacture, all media flaws are allocated to reserved
 sectors; therefore, they do not reduce the formatted capacity.

 Guaranteed formatted:         452.415 MB
 Guaranteed total sectors:     883,624
 Bytes per sector:             512


 Recommended logical configuration
 ---------------------------------
 The drive is configured in translation mode. DOS limits the number of
 sectors per track to 63. (The drive limits sector per track to 256).
 Set the number of heads to satisfy the following relationship:

 16   (sectors per track)(heads)   4,096

 When you configure the drive in CMOS, the logical sectors cannot
 exceed the physical capacity of the drive. The total logical capacity
 of the drive is determinated by the following formula:

 total sectors = (log. heads)(log. sectors per track)(log.cylinders)

 You can verify the number of sectors per track and the number of
 heads by using the Identify Drive command. To maximize the capacity
 of the drive, the following geometry is recommended:

 Cylinders            1018
 Read/Write Heads       14
 Sectors per Track      62


 Multisegment read look-ahead buffer
 -----------------------------------
 The drive uses the read lock-ahead buffer to improve performance by
 eliminating access times under certain conditions. The read look-
 ahead buffer contains four 64K-segments of RAM (one for writing and
 three for reading) for a total capacity of 256 Kbytes.

 This buffer is used to store the next logical sectors after the
 previously read sector into a buffer before those sectors are
 actually requested by the host. The read look-ahead buffer stores
 data from the start of a read until the buffer segment is full, or
 until another command is received from the host.


 Acoustics
 ---------
 34 dBA typical sound pressure at 1 meter, in Idle mode.
 38 sBA maximum sound pressure at 1 meter, in Idle mode.


 Access Time Definition and Timing
 ---------------------------------
 Seek time is a true statistical average of at least 5,000 measure-
 ments of seek time. All measurements are under nominal conditions of
 temperature and voltage with the drive mounted horizontally. In the
 table below, the following definitions apply:

 Track-to-track seek time is the average of all possible single-track
 seeks in both directions.
 Average seek time is measured by executing seeks in both directions
 between random cylinders.
 Full-stroke seek time is half the time needed to seek from track 0 to
 the maximum track and back to track 0.
       +----------------------------------+--------+
       |Track-to-Track         msec. typ. |   3.5  |
       |                       msec. max. |   4    |
       |               Average msec. typ. |  12    |
       |               Average msec. max. |  14    |
       |Full-Stroke            msec. typ. |  30    |
       |                       msec. max. |  32    |
       |Latency                msec. avg. |   6.67 |
       +----------------------------------+--------+
 NOTE: Host overhead varies between systems and cannot be specified.
       Drive internal overhead is measured by issuing a no-motion-
       seek. Overhead is typically less than 0.5 msec.


 UL/CSA Certification
 --------------------
 This drive is recognized in accordance with UL 478 and UL 1950.
 It's certified to VDE 0805/05.90 and EN 60950/1.88, as tested by VDE.
 It's also certified to CSA C22.2 No. 220-M1986, and CSA C22.2 No. 950

