
D 3 8 4 1    NEC
NO MORE PRODUCED                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 3.5"/HH               Cylinders     440|     |     |
Capacity form/unform    45/   56 MB        Heads           8|     |     |
Seek time   / track  28.0/ 8.0 ms          Sector/track   25|     |     |
Controller           SCSI1 SINGLE-ENDED    Precompensation 65535
Cache/Buffer               KB              Landing Zone
Data transfer rate    0.937 MB/S int       Bytes/Sector      512
                      0.937 MB/S ext
Recording method     RLL 2/7                        operating  | non-operating
                                                  -------------+--------------
Supply voltage     5/12 V       Temperature *C         5 50    |    -40 60
Power: sleep              W     Humidity     %         8 80    |      8 90
       standby            W     Altitude    km            3.000|        12.000
       idle               W     Shock        g         5       |     40
       seek               W     Rotation   RPM      3600
       read/write         W     Acoustic   dBA
       spin-up            W     ECC        Bit
                                MTBF         h      30000
                                Warranty Month
Lift/Lock/Park     -            Certificates                                  

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NEC      D3841  PRODUCT DESCRIPTION 806-520776-0 REV. 2

  +---------------------------------------------------------+
  |                                                         |XX
  |                                                    +-+  |XX
  |                                            Switch 1| |  |XX
  |                                                    +-+  |XX
  |                                                    +-+  |XX
  |                                            Switch 2| |  |XX J1
  |                                                    +-+  |XX
  |                                                    +-+  |XX
  |                                            Switch 3| |  |XX
  |                                                    +-+  |XX
  |                                                         |XX
  |                                                         |XX
  |                                                         |
  |                                                         |
  |                                                  XXXXXXX|Power
  +---------------------------------------------------------+




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NEC      D3841  PRODUCT DESCRIPTION 806-520776-0 REV. 2

 Jumper Setting
 ==============


  +----------------+  +----------------+  +----------------+ ON
  |        x x x x |  |x x x x x x x x |  |x x x x x x x x |
  |x x x x         |  |                |  |                |
  +----------------+  +----------------+  +----------------+
             +------TERM. ON/OFF SWITCH------------------+


 An SCSI bus cable and power cable are required to operate the drive.
 If two or more SCSI device are connected to the same SCSI bus cable,
 SCSI address setting and terminating resistor ON/OFF switch must be
 altered properly. The drive has a switch for accepting or rejecting
 an Auto Motor Start at power on and that for setting of ON/OFF of
 SCSI BUS parity check. These switches must be set depending on the
 operating conditions.



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NEC      D3841  PRODUCT DESCRIPTION 806-520776-0, REV. 2

 Notes On Installation
 =====================

 The D3841 magnetic disk drive can be installed both horizontally and
 vertically. When installing the drive horizontally, be sure to
 install it with the main pronted wiring assembly faced down. (Do NOT
 face the front panel upward or downward.)

 The drive has eight mounting tap holes.

 An SCSI bus cable and power cable are required to operate the drive.
 If two or more SCSI devices are connected to the same SCSI bus cable,
 SCSI address setting and terminating resistor ON/OFF switch must be
 altered properly. The drive has a switch for accepting or rejecting
 and Auto Motor Start at power on and that for setting of ON/OFF of
 SCSI BUS parity check. These switches must be set depending on the
 operation conditions.


 Drive Configuration
 -------------------
 This magnetic disk drive consists of a disk enclosure assembly that
 contains recording disks, magnetic heads, and a magnetic head drive
 mechanism; one printed wiring assemblies; a frame; and a front panel.


 Disk Enclosure Assembly
 -----------------------
 The disk enclosure assembly contains recording disks, magnetic heads,
 a head carriage mechanism, a DC motor with encoder, and an air
 filter. An inside-hub type DC brushless motor is used as a spindle
 motor to rotate recording disks. Air can go into or come out of the
 disk enclosure assembly only through the air filter provided on the
 top cover off the assembly. The air in the assembly is therefore kept
 highly clean.


 Printed Wiring Assembly
 -----------------------
 The pronted wiring assembly includes an SCSI interface circuit,
 buffer RAM, data manager, read/write control circuit, servo control
 circuit, and DC motor drive circuit to control all drive operations
 and interfaces. The spindle motor drive circuit is located in the
 spindle motor section and drives the spindle motor with control
 signals sent from the printed wiring assembly.


 Power Supply
 ------------
 The D3841 magnetic disk drive requires +5 VDC and +12 VDC power for
 operation.


 Dimensions
 ----------
 Height     41.3 mm
 Width     101.6 mm
 Depth     157   mm
 Weight     1.0  kg or less

 NOTE
 Front plate is not included


 Interface
 ---------
 This drive has connector J1 for connection to SCSI bus and connector
 J3 for power supply. The device connected at each furthest end of the
 cable must have a terminating resistor installed. If the initiator
 and targets use different power supplies, power for terminating
 resistor of the target should be supplied through pin 26 of the SCSI
 bus.

            Single Initiator, Single Target
            -------------------------------
     Initiator                           Target
     XXXXXXX <*****SCSI*Bus************> XXXXXX



             Single Initiator, Multi Target
             ------------------------------
     Initiator                           Target
     XXXXXXX <*****SCSI*Bus************> XXXXXX
                                   :
                                   :     Target
                                   :***> XXXXXX



             Multi Initiator, Multi Target
             -----------------------------
     Initiator                           Target
     XXXXXXX <*****SCSI*Bus************> XXXXXX
                     :             :
     XXXXXXX <*******:             :     Target
     Initiator                     :***> XXXXXX


 Connetcor J1
 ------------
 A 50-pin non-shielded connector used for interface to the SCSI bus.

 Fifty-conductor flat cables and 25-signal twisted-pair cables can be
 used for the SCSI bus. Cables of impedance 100 ohms   10% and
 conductor diameter 28 AWG or more should be used to match the
 impedance of the drive.


 Connector J3
 ------------
 Connector J3 for power supply is an AMP P/N 350211-1 or equivalent.

 The connector housing AMP P/N 1-480424-0 of the cable suits this
 connector. Select a power cable, considering the current consumption
 and cable length, and use connector pins that suit the cable
 material.

  |+-----J3-----+   pin 1    +12 VDC
  || 4  3  2  1 |   pin 2    +12 Volts Return
  |+------------+   pin 3    + 5 Volts Return
  +---------------- pin 4    + 5 VDC



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NEC      D3841  PRODUCT DESCRIPTION 806-520776-0 REV. 2


 Outline and Features
 --------------------
 The D3841 Magnetic Disk Drive has an unformatted storage capacity of
 56 megabytes with 3.75-inch magnetic disk media and mini Winchester
 magnetic heads incorporated, employing a Small Computer System
 Interface (SCSI).

 The magnetic head drive mechanism employs a DC motor with encoder,
 achieving high-speed seek and highly reliable read/write operations.
 A large capacity is also achieved with a 2-7 RLL modulation method
 adopted  for read/write operation.


 Logical Connection to SCSI Initiator
 ------------------------------------
 This drive operates as an SCSI target and has no initiator function.
 Logical connection to the SCSI initiator is executed according to the
 SCSI logical specifications.

 This drive has an arbitration function for disconnection/
 reconnection. It operates on the basis that the initiator has a
 disconnect/reconnect function, an SCSI Message Identify signal must
 be sent for a Disconnect message from the drive to indicate that the
 initiator does not have that function.

 In the non-arbitrating system, SCSI logical connection is executed
 in the information transfer phase through the selection phase, one of
 the SCSI bus phases, as a starting phase. In the arbitrating system,
 SCSI logical connection is executed in the information transfer phase
 through the arbitration phase and selection phase.


 Detecting Drive Errors
 ----------------------
 This drive has various self-diagnostic functions. It can read
 extebded sense data with a Request Sense command of the SCSI inter-
 face. You should execute a Request Sense command if an error occurs.

 Diagnoses other than for errors can be executed with a Send
 Diagnostic command. This drive supports the selftest specified with
 a Send Diagnostic command. If an error is detected, the check
 condition bit is set to "1". The detailed diagnosis result can be
 received by executing a Request Sense command.


 Power Off
 ---------
 Before power off for transporting, it is recommended that the host
 commands a Motor Stop command that makes retract the heads to the
 Contact Start Stop (CSS) area at inner most of disks.


 SCSI Interface Signals
 ----------------------
 The Unit employs a SCSI Single-Ended type interface.

 The Single-Ended type interface uses a terminal resistance of 220 /
 330 .

 The logical specification and the electrical specification of the
 signals dealt with in this section are as follows:

 1. Output Characteristics
    Signal assertion
    =0.0   0.4 VDC @ I=-48 mA
    Signal negation
    =2.5   5.25 VDC

 2. Input charateristics
    Signal true : "1"
    =0.0   0.8 VDC @ I=500  A
    Signal false : "0"
    =2.0   5.25 VDC
    (minimum input hysteresis = 0.2 VDC)

 3. Terminator power
    VTerm = 4.0  5.25 VDC @ I=800 mA


