M 8 4 2 5 S MINISCRIBE
NO MORE PRODUCED Native| Translation
------+-----+-----+-----
Form 3.5"/HH Cylinders 612| | |
Capacity form/unform 21/ 25 MB Heads 4| | |
Seek time / track 68.0/15.0 ms Sector/track 17| | |
Controller SCSI1 SINGLE-ENDED Precompensation
Cache/Buffer 1 KB DUAL-PORTED Landing Zone
Data transfer rate 1.000 MB/S int Bytes/Sector 512
MB/S ext
Recording method RLL 2/7 operating | non-operating
-------------+--------------
Supply voltage 5/12 V Temperature *C 4 50 | -40 57
Power: sleep W Humidity % 8 80 |
standby W Altitude km -0.061 3.048|
idle 13.0 W Shock g 8 | 50
seek W Rotation RPM 3600
read/write W Acoustic dBA 50
spin-up W ECC Bit 32
MTBF h 20000
Warranty Month
Lift/Lock/Park YES Certificates CSA,FCC,UL1950
**********************************************************************
L A Y O U T
**********************************************************************
MINISC. 8425S PRODUCT MANUAL P/N 1052 REV. B, JULY 24, 1987
+---------------------------------------------------------+
| F1xx|Fuse
| +------1 ++|XX
| +------+ |||XX
| Drive |||XX
| Select RP3+|XX
| ++|XX J1
| |||XX
| |||XX
++ RP2+|XX
++ ++|XX
| |||XX
| |||XX
| RP1+|XX
| |XX
| | 1
| |
+---------------------------------------------------------+
XXXXXX J3
Power
**********************************************************************
J U M P E R S
**********************************************************************
MINISC. 8425S PRODUCT MANUAL P/N 1052 REV. B, JULY 24, 1987
Jumper Setting
==============
Drive Select
------------
+-----------+
|o o o o o 1|
|o o o o o o|
+-----------+
| | | | | +- SEL 0
| | | | +--- SEL 1
| | | +----- SEL 2
| | +------- D (Disable Parity)
| +--------- E (Low Powered)
+----------- F (Diagnostics)
Addressing
----------
Communication on the SCSI bus is allowd between only two (2) SCSI
devices at any given time. There is a maximum of eight (8) SCSI
devices. Each SCSI device has an SCSI ID bit assigned.
When two (2) SCSI devices communicate on the SCSI bus, one acts as an
Initiator and the other acts as a Target. The Initiator originates
an operation and the Target performs the operation.
An Initiator may address up to eight (8) Logical Units (LUN) attached
to one Target. The M8-SCSI has only one Logical Unit Attached (LUN =
0).
Address selection on the M8-SCSI is accomplished by the use of three
jumpers:
| 0 1 2 3 4 5 6
------+--------------
SEL 0 | 0 1 0 1 0 1 0
SEL 1 | 0 0 1 1 0 0 1
SEL 2 | 0 0 0 0 1 1 1
When left OPEN, the corresponding bit is a ZERO (0).
Mode Jumpers
------------
Three additional jumpers are supplied on the M8-SCSI Printed Circuit
Board (PCB) with the following functions when SHORTED:
Jumper D Disable Parity
Jumper E Low Power/Auto Park Mode
Jumper F Invokes Offline Diagnostics following reset, which consists
of infinite seek tests (random or oscillating).
**********************************************************************
I N S T A L L
**********************************************************************
MINISC. 8425S PRODUCT MANUAL P/N 1052 REV. B, JULY 24, 1987
Notes on Installation
=====================
Recommended Mounting Configuration
----------------------------------
The MiniScribe 8425 SCSI quarter size drive is designed to be used in
applications where the unit may experience shock and vibrations at
greater levels than larger and heavier disk drives.
Two features which allow greater shock tolerances are the use of
rugged media and shock mounts. To take full advantage of the shock
mounts, however, it is necessary to provide a 0.1 inch clearance on
both the top and bottom of the drive. This clearance allows for move-
ment of the drive during acceleration.
The drive may be mounted in any attitude.
The drive is mounted using 6-32 screws, 1/8 inch maximum penetration.
The customer should allow adequate ventilation to the drive to insure
reliable drive operation over the operating temperature range.
Mechanically Isolated Mounting Points
-------------------------------------
Four side mounting and four base mounting points are provided to the
customer. Each mounting point is mechanically isolated from the
head/disk assembly.
Magnetic Field
--------------
The externally induced magnetic flux density may not exceed 3 Gauss
as measured at the disk surface.
Read/Write Electronics
----------------------
One integrated circuit is mounted within the sealed enclosure in
close proximity to the read/write heads. Its function is to provide
one (1) of four (4) head selection, read preamplification and write
drive circuitry.
Drive Mechanism
---------------
A brushless DC direct drive motor rotates the spindle at 3600 rpm.
The motor/spindle assembly is dynamically balanced to provide minimal
mechanical runout to the disks. A dynamic brake is used to provide a
fast stop to the spindle motor when power is removed.
Air Filtration System
---------------------
Within the sealed enclosure, a 0.3 micron filter coupled with a
breather filter provides over the drive life a clean, above
atmospheric pressure environment to the heads and disks.
Head Positioning Mechanism
--------------------------
Four read/write heads are supported by a carriage mechaism coupled to
the stepper motor through a rack-and-pinion motion translator.
Read/Write Heads and Disks
--------------------------
Data is recoreded on two (2) 95 mm diameter disks through four (4)
low force, low mass Mini-Winchester type ferrite heads.
Caution/Warning
---------------
The Miniscribe drive is a precision product weighing 1.8 pounds.
During handling the unit must not be dropped, jarred or bumped.
Otherwise, damage to the heads and disks may occur. When the drive is
removed from the Miniscribe shipping container and not immediately
secured within a chassis through its shock mounts, it must be stored
on a soft padded surface.
Failure to comply with the above procedure will render null and void
all warranties.
Electrical Interface
--------------------
The Small Computer System Interface (SCSI) on the M8-SCSI uses single
ended drivers and receivers, which allow a maximum cable length of 20
feet (6 meters) from the first to the last device (up to 8 devices)
on the bus.
All assigned signals are terminated with 220 ohms to +5 volts and 330
ohms to ground at each end of the cable. All three (3) terminator
networks on the M8-SCSI are removable.
All signals driven by the M8-SCSI are Open Collector and have the
following output characteristics:
Signal Assertion 0.0 VC to 0.4 VDC
Max. Driver Output 48 mA (sinking) @ 0.5 VDC
Signal Negation 2.5 to 5.25 VDC
All signals received by the M8-SCSI shall have the following input
characteristics:
Signal True 0.0 VDC to 0.8 VDC
Max. Total Input Load -0.4 mA @ 0.4 VDC
Signal False 2.0 to 5.25 VDC
Min. Input Hysteresis 0.2 VDC
J1 SCSI Connector
-----------------
A 50 pin flat ribbon connector is provided at J1. The 3M P/N 3425-
3000 cable connector is recommended.
Pin 26 Term Power
Termpower is +5 volts thru a 1 amp microfuse. Loss of this fuse will
result in the disk drive appearing dead. Reversal of the connector
with pin 25 grounded will cause this fuse to blow.
J3 Power Connector
------------------
Power is applied through J3, a 4 pin AMP connector. The recommended
mating connector is AMP P/N 1-480424-0 utilizing pins AMP P/N
350078-4.
+-----J3-----+ pin 1 +12 VDC
| 4 3 2 1 | pin 2 +12 Volts Return
+------------+ pin 3 + 5 Volts Return
pin 4 + 5 VDC
Cable Connection
----------------
Single Host, Single Drive
+-------+ +-------+
| HOST +----SCSI-Bus--------+ M8-S |
| X+--------------------+ X|
+-------+ +-------+
Single Host, Multiple Drives
+-------+ +-------+
| HOST +----SCSI-Bus--------+ M8-S |
| X+------+ +----------+ |
+-------+ | | +-------+
| | +-------+
| +----------+ M8-S |
| +----------+ |
| | +-------+
| | +-------+
| +----------+ M8-S |
+-------------+ X|
+-------+
Multiple Host, Multiple Drives
+-------+ +-------+
| HOST +----SCSI-Bus--------+ M8-S |
| X+------+ +----------+ |
+-------+ | | +-------+
| | +-------+
| +----------+ M8-S |
| +----------+ |
| | +-------+
+-------+ | | +-------+
| HOST +------+ +----------+ M8-S |
| X+--------------------+ |
+-------+ +-------+
X = Terminator Installed
**********************************************************************
F E A T U R E S
**********************************************************************
MINISC. 8425S PRODUCT MANUAL P/N 1052 REV. B, JULY 24, 1987
Introduction
------------
The MiniScribe M8-SCSI (Small Computer System Interface - ANSI
X3.131-1986) series of 3 1/2 inch disk drives are half height random
access storage devices of 21 Megabytes of formatted data (25 MB un-
formatted) containing 2 plated disks and utilizing Winchester style
flexure technology.
High performance and high unit reliability are achieved by the
utilization of a proven microprocessor spin control and rack-and-
pinion stepper mechanism. The heads, disks and actuator assemblies
are within a sealed enclosure containing recirculating and breather
filters to supply clean air and equalized pressure to the head and
disk environment. Quality mechanical construction with a sophistica-
ted single printed circuit board allows for maintenance-free
operation throughout the life of the drive.
The M8-SCSI series disk drive uses the industry standard Small
Computer System Interface (SCSI) compatible interface capable of up
to 1 Megabyte/second (8 megabits/second) data transfer rate. The
drive also features power up, user invoked or offline diagnostics and
has full support of disconnection. Defect handling is entirely
transparent to the host system as well as seek retry and error
correction.
The unit size and shock mounting are identical to the industry
standard half height 3 1/2 mini floppy mounting dimensions and it
uses the same power connector.
Track Zero Detector
-------------------
The Track Zero Detector resides on the stepper motor. This optical
sensor consists of a light source and a receiver which when blocked
by an interrupter on the motor shaft indicates one of several logical
Track Zero positions. The microprocessor determines the physical
location of Track Zero from the redundant logical Track Zeros.
Seek Time
---------
+----------------------------------+--------+
| | 8425S |
+----------------------------------+--------+
|Track-to-Track msec. typ. | 15 |
+----------------------------------+--------+
|Average msec. typ. | 68 |
| msec. max. | 150 |
+----------------------------------+--------+
|Latency msec. avg. | 8.33 |
+----------------------------------+--------+
Media Defect Criteria
---------------------
All defects are preassigned from the factory.
Host Interface and Data Buffer
------------------------------
The host interface and data buffer are integrated in one single
semicustom circuit with the following features:
ANSI X3.131-1986 compatible (SCSI) Host interface operating in Target
mode only.
Capable of Arbitration and disconnection.
Parity generation and checking (user selectable).
Dual ported 1024 bytes buffer, eliminates the need for sector inter-
leaving (1 to 1).
Defect Management
-----------------
There is one (1) alternate block allocated for each cylinder for a
total of 612 allocated alternate blocks. This assures adequate
coverage defective blocks and decreases the time necessary to react
to alternate blocks.
Diagnostic and Exercise Routines
--------------------------------
The microprocessor performs wake up diagnostics upon application of
power. If an error is detected, the processor will flash a warning by
blinking the activity LED. Some errors are fatal in that they do not
return to the program until power is cycled.
If no errors are detected, the processor tests Jumper E to determine
its state (open or closed). Briefly, Jumper E (Drive Exercise
Options) is as follows:
Power-up sequence of events is as follows:
1. Apply power
2. The microprocessor runs power on diagnostics and then allows motor
spin up.
3. Test Jumper E. If open, go to normal operation. If closed,
continue to Step 4.
4. Display code level (5 bits), e.g. 00001
5. Recalibrate access, then seek to maximum cylinder.
6. At this point the sequential seek burn-in will begin.
Error codes may be generated by the microprocessor to indicate hard-
ware failures or warnings that are detected during power-on
diagnostics, burn-in mode, or normal operation. Error codes are
diaplayed in a "morse-code" type manner. Bits may be interpreted
and converted into hexadecimal error codes. "Zeros" are indicated by
a short (1/2 second) flashingn mode. "Ones" are indicated by a short
(1/2 second) continuous ON mode. Error "Words" are separated by a one
second LED off time.
Zero = 0.5 second flashing mode
One = 0.5 second continuous ON mode
Between Bits = 0.3 second Off
Between Repeat Cycles = 1.0 second Off
Listed Below are the binary to hexadecimal conversion values:
0 = 0000 4 = 0100 8 = 1000 C = 1100
1 = 0001 5 = 0101 9 = 1001 D = 1101
2 = 0010 6 = 0110 A = 1010 E = 1110
3 = 0011 7 = 0111 B = 1011 F = 1111
Message Definitions
-------------------
Code 0 - Microprocessor RAM error
Code 1 - Microprocessor ROM checksum error
Code 2 - Interface chip diagnostic failure
Code 3 - Write Fault latch will not reset
Code 4 - Index pulse not detected during spinup
Code 5 - Unable to reach 3600 rpm in 600 revs.
Code 6 - Unable to stabilize spin speed in 10 seconds
Code 7 - Unable to maintain spin speed to 0.5%
Code 8 - Unable to uncover Track Zero sensor
Code 9 - Unable to cover Track Zero sensor
Code A - Track Zero interrupter misadjusted
Code B - Shipping zone error, crash stop misadjusted
Code C - Carriage stuck during recal error
Code D - Seek errror during burn-in or recal
Code E - No hall transitions during spin-up
Code F - Unexpected interrupt from processor
