Hard Drive: NEC: D3856 105MB 3.5"/SL SCSI1 SE
D 3 8 5 6 NEC
NO MORE PRODUCED Native| Translation
------+-----+-----+-----
Form 3.5"/SLIMLINE Cylinders 1251| | |
Capacity form/unform 105/ 131 MB Heads 4| | |
Seek time / track 19.0/ 8.0 ms Sector/track 41| | |
Controller SCSI1 SINGLE-ENDED Precompensation
Cache/Buffer 64 KB LOOK-AHEAD Landing Zone
Data transfer rate MB/S int Bytes/Sector 512
1.500 MB/S ext ASYNC
Recording method RLL 1/7 operating | non-operating
-------------+--------------
Supply voltage 5/12 V Temperature *C 5 50 | -40 60
Power: sleep W Humidity % 8 80 |
standby 1.3 W Altitude km 3.000| 12.000
idle 2.6 W Shock g 5 | 55
seek W Rotation RPM 3456
read/write 4.8 W Acoustic dBA
spin-up W ECC Bit 56
MTBF h 50000
Warranty Month
Lift/Lock/Park YES Certificates
Layout
NEC D3856 THERORY OF OPERATION 806-521348-0 REV. 1 1991
+---------------------------------------------------------+ | |XX | SW1 ++ |XXJ1 | OFF 1--+ON || |XX | | | || |XX I | 4--+ || |XX N | ++ |XX T | TERMINATING ++ |XX E | RESISTORS || |XX R | || |XX F | || |XX A | ++ |XX C | |XX E |+-+LED |X1 |+-+CONNECTOR JP1 JP2 JP3 | | J8 +-+-+-+ |XXJ3 | +-+-+-+ |XX Power +---------------------------------------------------------+ 1
Jumpers
NEC D3856 THEORY OF OPERATION 806-521348-0 REV. 1, 1991
Jumper Setting
==============
x = Jumper set at factory
SW1 SCSI ID
------------
0 1 2
| | |
+----------+-----------------------+ +4--3--2--1-+
| SCSI ID | Jumpers | OFF|. X X X | OPEN
| | 1 | 2 | 3 | ON |X . . . | CLOSED
+----------+-------+-------+-------+ ++----------+
|x 0 | OPEN | OPEN | OPEN | |
| 1 | OPEN | OPEN | CLOSED| Parity Check Option
| 2 | OPEN | CLOSED| OPEN |
| 3 | OPEN | CLOSED| CLOSED|
| 4 | CLOSED| OPEN | OPEN |
| 5 | CLOSED| OPEN | CLOSED|
| 6 | CLOSED| CLOSED| OPEN |
| 7 | CLOSED| CLOSED| CLOSED|
+----------+-------+-------+-------+
The Unit is shipped with the SCSI address set to "0" at the factory.
When plural units are to be linked to one single SCSI bus, change the
SCSI address by the switch SW1.
SW1 Parity Check Option
------------------------
4 OPEN SCSI Parity Check diabled
CLOSED SCSI Parity Check enabled
JP1 and JP2
-----------
JP1 and JP2 are used for inspection purposes at the factory. Please
refraim from touching them.
JP3 Auto Power Save
--------------------
The function is selected by inserting a short-circuiting plug in JP3.
Short-circuiting plug present:
Auto power save on.
Short-circuiting plug not present:
Auto power save off.
NOTES
The setting of SCSI addresses and the selection of Auto Power Save
function are read and stored at the time of reset or power-on.
The selection of the parity check On/Off function is enabled as soon
as it is set.
Setting of Optional Functions
-----------------------------
This Unit offers two optional functions: the Auto Power Save option
to automatically put the Unit in Power Save mode when no access is
made to the HDD over a certain time period; and the other option to
select ON/OFF of the SCSI bus parity check function. The Unit comes
from the factory with the Autp Power Save option inhibited and the
parity check function set to ON.
Moreover, the short-circuiting plug to be used for setting the said
Auto Power Save function (JP3) has to be an equivalent product to the
Dupont 68905-001.
Installation/Removal of Terminating Resistors
---------------------------------------------
In the case where multiple SCSI devices are to be connected to the
same SCSI bus, the terminating resistors have to be removed for all
the SCSI devices connected except for the one to be located at the
farthest end of the cable.
This Unit is shipped out of the plant with the terminating resistors
installed. Remove these terminating resistors from all the SCSI
devices but not the one which is situated at the farthest end of the
cable.
Install
NEC D3856 THEORY OF OPERATION 806-521348-0 REV. 1, 1991
Notes on installation
=====================
Drive mounting
--------------
horizontally vertically
+-----------------+ +--+ +--+ +------------------+
| | | +-----+ +-----+ | | | x
| | | | | | | | x+----------------+x
+-+-----------------+-+ | | | | | | ||x x||
+---------------------+ | | | | | | || x x ||
| | | | | | || x x ||
x x | | | | | | || x x ||
+------x------x-------+ | +-----+ +-----+ | || xx ||
+-+------x--x-------+-+ +--+ +--+ || x x ||
| xx | || x x ||
| x x | || x x ||
+---x--------x----+ |x x|
x x x++----------------++x
Installation
------------
The D3856 Magnetic Disk Unit can be mounted horizontally as well as
vertically. In horizontal installation, mount the Unit in such a
posture that its printed-circuit board will be situated below (The
unit cannot be mounted with the interface connector J1 and the power
connector J3 positioned above or below.
The unit has 10 mounting screw holes. Use these mounting screw holes
for installing the Unit. Screws: M3x0.5, minimum depth: 4 mm
Operation of the Unit requires a SCSI bus cable and a power supply
cable. In case multiple SCSI device are going to be connected to one
single SCSI bus, it is necessary to set up their SCSI addresses and
to install/remove terminating resistors accordingly. Further, this
Unit comes with a jumper (JP3) for adding the Auto Power Save option,
and switch contacts for setting the parity check On/Off function of
the SCSI bus. This settings will have to be done as needed according
to the operating conditions of the Unit.
Transportation and Precautions
------------------------------
When Transporting the Unit, exert extreme care so as to prevent it
from being subjected to excessive shock and vibration. It is
recommended to use the same packing box of the Unit for transporta-
tion or storage.
Avoid taking any action that would expose directly to the outside
air the disk enclosue in which the magnetic disk media and magnetic
heads are sealed.
Printed-Circuit Board Assembly
------------------------------
This assembly incorporates an SCSI interface circuit, buffer RAM,
data manager, read/write control circuit, servo-control circuit and
spindle motor drive circuit. It exerts control on the overall opera-
tion of the Unit and the Interface.
Frame
-----
The Unit comes in frame having 10 mounting screw holes. This frame is
insulated from the disk enclosure assembly with shock absorber. In
configuring an integral system with the Unit, see to it that the disk
enclosure assembly will spearated from the system cabinet with a
clearance of at least 2.54 mm provided around the Unit.
Power Disconnection ------------------- When the power voltages of +5 VDC or +12 VDC has dropped below the specified value, this Unit interprets it as power outage. Upon power off, the Autoretract function of the Unit activates to automatically move the magnetic head to the Contact Start Stop (CSS) area.
Interface Specification
-----------------------
The Unit is provided with connector J1, used for connection to SCSI
bus, and connector J3 for power supply. The unit to be located at the
farthest end of the cable has to be fitted with terminating
resistors. When Initiator and Target differ from each other in power
source, it is recommended to supply power for terminaing resistance
from Pin 26 of SCSI bus.
Single Initiator/Single Target
+----------------+ +---------------+
| Initiator +--------------------+ Target |
| | | |
+----------------+ +---------------+
Single Initiator/Multi Target
+----------------+ +---------------+
| Initiator +-----------+--------+ Target |
| | | | |
+----------------+ | +---------------+
|
| +---------------+
+--------+ Target |
| |
+---------------+
Multi Initiator/Multi Target
+----------------+ +---------------+
| Initiator +-------+---+--------+ Target |
| | | | | |
+----------------+ | | +---------------+
| |
+----------------+ | | +---------------+
| Initiator +-------+ +--------+ Target |
| | | |
+----------------+ +---------------+
Connector J1
------------
A 50-pin nonshielded connector is use for interface with SCSI bus.
For SCSI bus, a 50-Conductor Flat cable or 25-Single Twisted Pair
cable can be used. For impedance matching, a cable of 100 ohms 10%
of impedance, with conductor diameter larger than 28 AWG is
recommended.
Example of recommended connector on J1 cable side:
Du Pont 66900-250 or equivalent (Integrated housing and pins).
Connector J3
------------
The power supply connector J3 is AMP P/N350211-1 or equivalent.
The AMP P/N 1-480424-0 is applicable to a connector housing on the
cable side. In selecting a power cable, take into account the current
consumption of the Unit and the necessary length of the cable itself,
and use connector pins of material applicable to that of the
conductors.
+----------------------- | +--J3--------+ +-J1- pin 1 +12 V DC | | 1 2 3 4 | | 1 pin 2 +12 V DC Return | +------------+ +-- pin 3 +5 V DC Return +------------------ pin 4 +5 V DC
Connectors J1 and J3 are molded as a unit.
Connector J8
------------
This Unit is provided with a signal connector used to illuminate LED
to indicate that the Unit is busy in exchanging data/command to and
from the Initiator.
The signal connector is ELCO 00 8283 0211 00000 or equivalent.
The ELCO 60 8283 3028 45000 is applicable to a housing on the cable
side and ELCO 60 8283 0513 99 808 is a receptacle contact.
+-----+
|1 2| 1: LED, Anode
----+-----+PWB- 2: LED, Cathode
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
Features
NEC D3856 THEORY OF OPERATION 806-521348-0 REV. 1, 1991
Outline and Features
--------------------
The D3856 is a magnetic disk unit using 3.75" magnetic disk media and
mini-Winchester type magnetic heads with an unformatted storage
capacity of 131.3 Mbytes and adopts a SCSI interface (Small Computer
System Interface).
The rotary voice coil motor employed in the magnetic head drive
mechanism allows to realize write and read operations with high-speed
seek and high reliability, and its write system adopts the 1-7 RLL
modulation method.
Features
--------
The use of the Winchester technique has made it possible to
accommodate the magnetic disk media and magnetic head section in an
enclosed aluminium-alloy enclosure, which perfectly protects them
from outside dust for higher reliability.
The sector-servo method is adopted, in which servo signal are
obtained from the data recording surface for positioning the magnetic
head, and the type voice coil motor in use has allowed to attain a
high-speed seek in 19 ms of average seek time.
The magnetic disk medium comes with a CSS (Contact Start Stop) area
at the innermost circumference, which, coupled with an Auto Retract
and Auto Carriage Lock mechanisms, assures a high reliability against
vibration and shock during transportation.
The Unit adopts an interface conforming to the ANSI X3.131-1986 small
computer system interface, which is standard for small computer
systems.
The Unit supports SCSI CCS (Common Command Set), as well as various
option commands that are convenient for controlling the unit.
The Arbitration function and the Disconnect/Reconnect function
provided in the Unit serve to make an efficient use of the SCSI Bus.
An Asynchronous Single Ended interface is in use.
The Read Look Ahead Cache function is supported.
High speed processing is availabe, as it allows to use the magnetic
disk unit having 1.5 megabyte/sec. of read-write capabilities with
1:1 interleaving.
Seek Time
---------
+----------------------------------+--------+
| | D3856 |
+----------------------------------+--------+
|Track-to-Track msec. typ. | 8 |
+----------------------------------+--------+
|Average msec. typ. | 19 |
| msec. max. | 37 |
+----------------------------------+--------+
|Latency msec. avg. | 8.68 |
+----------------------------------+--------+
Logical Connection with SCSI Initiator
--------------------------------------
This Unit, operating as the SCSI target, has no initiator function.
Logical connection of the Unit and the SCSI initiator is performed
in accordance with the SCSI logic specification. This Unit is
provided with the Arbitration function which can Disconnect/Reconnect
the logical connection with the SCSI initiator. If the initiator has
no Disconnect/Reconnect function by either sending the Identify (80H)
of SCSI message or sending Message Reject code in response to the
Disconnect request from this Unit.
The logical connection of SCSI starts with the Bus Free Phase which
is one of SCSI Bus Phases. The connection is terminated at the
Information Transfer Phase via the Selection Phase in the case of the
Non-arbitration system, and terminated at the Information Transfer
Phase via the Arbitration Phase and the Selection Phase in the case
of the Arbitration system.
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