Seagate ST-506 User manual

8T506
PRODUCT
MANUAL
. c5S» seagate

ST506
Product Manual
July 4,1983
36036-001
920 Disc Drive, Scotts Valley, CA 95066-4544, USA
Telephone: [phone] • Telex: 176455SEAGATE SCVL
c559 seagate

Copyright Notice
This manual and all the
material contained in it are copyrighted with
all rights reserved. This manual may not be copied, in whole or in
part,
without written consent of Seagate Technology.
Seagate reservesthe right
to change, without notice, the specifications
contained in this manual.

TABLE OF CONTENTS
SECTION
PAGE
1.0 Introduction .................................................. .
1.1 General Description ........................................ .
1.2 Specification Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2
1.2.1 Physical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2
1.2.2 Reliability Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2
1.2.3 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3
1.2.4 Functional Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3
2.0 Functional Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.1 General Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.2 Read/Write and Control Electronics. . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.3 Drive
Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.4 Air Filtration System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
2.5 Positioning Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
2.6 Read/Write Heads and
Discs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
3.0 Functional Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
3.1 Power Sequencing .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
3.2 Drive Selection
..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8
3.3 Track Accessing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 8
3.4 Head Selection ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8
3.5 Read Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8
3.6
Write Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8

SECTION PAGE
4.0 Electrical Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
4.1 Control Input Lines .......................................... 14
4.1.1 Reduced Write Current .................................. 14
4.1.2 Write Gate ............................................. 15
4.1.3 Head Select 2°, 2' ....................................... 15
4.1.4 Direction In ............................................ 15
4.1.5 Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1.6 Drive Select 1-4 ......................................... 17
4.2 Control
Output Lines ........................................ 17
4.2.1 Seek Complete ......................................... 18
4.2.2 Track 0 ................................................ 18
4.2.3 Write Fault ............................................ 18
4.2.4 Index .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19
4.2.5 Ready ................................................. 19
4.3 Data Transfer Lines ................................ .I. ........ 19
4.3.1 MFM Wr.ite Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3.2 MFM Read Data ........................................ 21
4.3.3 Read/Write Timing ...................................... 21
4.4 Drive Selected .............................................. 21
4.5 Customer Options ........................................... 22
4.5.1 Radial Operation Option ................................. 22
4.5.2 "0" (Defeat Recal.) Operation ............................. 22
4.5.3 "H" Half Step Option .................................... 22
4.5.4 Nylon Ground Washer ................................... 22
5.0 Physical Interface .............................................. 24
ii

SECTION PAGE
5.1 J1/P1 Connector-Control Signals .............................. 25
5.2 J2/P2 Connector-Data Signals ................................. 25
5.3 J3/P3 Connector-DC Power ................................... 26
5.4 J10/P10 Frame Ground Connector ............................. 27
6.0 Physical Specifications ......................................... 29
6.1 Mounting Orientation ........................................ 29
6.2
Mounting Holes ............................................. 29
6.3 Physical Dimensions ........................................ 29
7.0 Track Format . ................................................. 32
7.1 Gap 1 ..................................................... 33
7.2 Gap 2 .......... " ......................................... 33
7.3 Gap 3 ..................................................... 33
7.4 Gap 4
...... " .. " .. , ...................................... 34
7.5 Defective Sector Flags ....................................... 34
LIST OF ILLUSTRATIONS
FIGURE PAGE
1.0 Air Filtration System/Head Disc Assembly. . . . . . . . . . . . . . . . . . . . . . . .. 5
2.0 Spindle Hub Air Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6
3.0 Positioning Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6
4.0 Power Up Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
5.0 Control Signals ................................................ 11
6.0 Data Signals ................................................ " 12
7.0 Typical Connections, 4 Drive System .............................. 13
iii

FIGURE PAGE
8.0 Control Signals Driver/Receiver Combination ....................... 14
9.0 Step General Timing ............................................ 16
9.1 Slow Seek Step Pulse Timing ................................... 16
9.2 Algorithm Driven Seek ......................................... 16
10.0 Index Timing ................................................. 19
11.0 Data Line Driver/Receiver Combination ........................... 20
12.0 Write Precompensation Patterns ................................ 20
13.0 Read/Write Data Timing ........................................ 21
14.0 Option Shunt Block ........................................... 23
15.0 Interface Connector Physical Locations .......................... 24
16.0 J1 Connector Dimensions ...................................... 25
17.0 J2 Connector Dimensions ...................................... 26
18.0 J3 Connector ................................................. 26
19.0 Mounting, Physical Dimensions ................................. 30
20.0 Overall Physical Dimensions .................................... 31
21.0 Track Format Example ......................................... 32
22.0 "A1" Address Mark Byte ....................................... 33
LIST OF TABLES
TABLE PAGE
I J1/P1 Connector Pin Assignments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
II J2/P2 Connector Pin Assignments ................................ 10
III J3/P3Connector Pin Assignments ................................ 10
IV DC Power Requirements ............... : ........................ 27
V Motor Start Current Requirements ............................... 28
iv

1.0 Introduction
1.1 General Description:
The ST506
disc drive is a random access storage device utilizing two
non-removable 51/4 inch discs as storage media. Each disc surface
employs one read/write head to service 153 tracks.
Low
cost and unit reliability are achieved through the use of a band
actuator and open loop stepper head positioning mechanism. The
inherent simplicity of mechanical construction and electronic con-
trols allow maintenance free operation throughout the life of the
drive. Both PC Boards are mounted outside the Head Disc Assembly
(HDA), allowing field serviceability.
Mechanical and contamination protection for the heads, actuator,
and
discs is provided by an impact resistant aluminum enclosure. An
integral air recirculating system provides clean air through a 0.3
micron filter. A second port in the filter assembly allows ambient air
pressure equalization
without chance of contamination. A patented
spindle pump assures adequate air
flow and uniform temperature
distribution throughout the head and disc area. Thermal isolation of
the stepper and spindle motor assemblies from the disc enclosure
results in a very low temperature rise within the HDA. This provides
significantly greater off-track margin and the ability to immediately
perform read and write operations after power up with no thermal
stabilization delay.
The ST506 is identical in size and mounting configuration to the in-
dustry standard minifloppy disc drives. They use the same DC
voltages, and no AC power is required.
Key Features:
• Storage Capacity of 6.38 megabytes unformatted,
5.0 megabytes formatted.
• Same physical size and mounting as the minifloppy.
• Same DC voltages as the minifloppy.
• Band actuator and stepper motor head positioning.
• 5.0 megabit/second transfer rate.
• Simple floppy-like interface.
• Same track capacity as a double density 8 inch floppy.
-1-

1.2 Specification Summary
1.2.1 Physical SpecificationsIEnvironmental Limits
Ambient Temperature
Operating:
Non-operating: 40°
to 122°F (4° to 50°C)
-40° to 140°F (-40° to 60°C)
Maximum Temperature Gradient
Operating: 18°F/hour or 10°C/hour
Non-operating: Below condensation
Relative Humidity:
Maximum Wet Bulb:
Maximum elevation
Operating:
Non-operating:
8
to 80% non-condensing
78.8
of (26°C)
10,000 feet
-1,000
to 30,000 feet
Maximum Shock Without Incurring Physical Damage
Operating: 10G's*
Non-operating: 20G's*
*No mechanical damage
wi" occur within these limits.
D.C. Power Requirements
+ 12V ±5%, 1.6A typical, 3.5A (At power on)
+ 5V ±5%, .7A typical, 1.0A (Maximum)
Maximum Ripple: 50mV peak to peak
(12V, 5V)
Mechanical Dimensions
Height:
Width:
Depth:
Weight:
Shipping Weight:
Heat Dissipation
Typical:
Maximum:
3.25 inches
5.75 inches
8.00 inches
4.6 pounds
(2.1 Kg)
9.0 pounds (4.1 Kg)
25 watts
29 watts
Maximum Accoustic Output: 50DBA @ 12" distance
1.2.2 Reliability Specifications
MTBF: 11,000 POH, typical usage
MTTR:
30 minutes
PM: Not required
Component design life: 5 years
-2-

Error Rates
Soft Read Errors*: 1 per 10
10
bits read
Hard Read Errors**: 1 per 10
12
bits read
Seek Errors: 1 per 10
6 seeks
*Recoverable
within 16 retries
**Not recoverable within 16 retries
1.2.3 Performance Specifications
Capacity
Per Drive:
Per Surface:
Per Track:
Access Time
Track To Track
Average*:
Maximum*:
Settling Time:
Formatted
5.0 Megabytes
1.25 Megabytes
8,182 Bytes
205 ms
*Using fast seek (includes settling)
Transfer Rate:
Average Latency: 8.33
ms
1.2.4 Functional Specifications
Rotational Speed:
Recording Density:
Flux Density:
Track Density:
Cylinders: .
Tracks:
Read/Write Heads:
Discs:
·3·
Unformatted
6.38 Megabytes
1.59 Megabytes
10,416 Bytes
3ms
85 ms
15ms ±10%
5.0 Mbits/sec
3,600 RPM ± 1%
7,690 BPI
7,690 FCI
255 TPI
153
612
4
2

2.0 Functional Characteristics
2.1 General Operation:
The
STS06 disc drive consists of read, write, and control electronics,
read/write heads, track positioning actuator, media, and air filtration
system. The components perform
the following functions:
1. Interpret and generate control signals.
2. Position the heads over the desired track.
3. Read and Write data.
4. Provide a contamination free environment.
2.2 Read/Write and Control Electronics
The electronic are packaged on two printed circuit boards. The Main
Control PC Board, to which power, control, and data signals are con-
nected includes:
1. Index detection circuit.
2.
Head position/actuator circuit.
3.
Drive up-to-speed circuit.
4. Drive select circuit.
5. Read/write circuits.
6. Head select circuit.
7. Write fault detection circuit.
8. Stepper
motor drive circuit.
9. Track 0 detector circuit.
The
Motor Control PCB provides the speed, power and braking con-
trols for the spindle motor. The Motor Control PCB derives its' power
from and is mounted below the Main Control
PC Board.
2.3 Drive Mechanism
A direct drive brushless DC motor rotates the spindle at 3600RPM.
The spindle motor is thermally isolated from the HeadlDisc assembly
(HDA) to minimize temperature rise within the sealed HDA chamber.
The
motor and spindle are dynamically balanced to ensure a low
vibration level. The HDA is shock mounted to minimize transmission
of vibration from the chassis or frame.
-4-

2.4 Air Filtration System (Figures 1.0 & 2.0)
The discs and read/write heads are fully enclosed in a chamber using
an integral air recirculation system and a 0.3 micron filter to maintain
a clean environment. The
filter also contains a port which permits am-
bient pressure equalization without contaminate entry.
2.5 Positioning Mechanism (Figure 3.0)
The read/write heads are mounted on a ball bearing supported car-
riage which is positioned by a band actuator connected to the step-
per motor shaft. The stepper motor is thermally isolated from the
HDA to minimize temperature rise within the sealed chamber.
2.6 Read/Write Heads and Discs
The recording media
consists of a lubricated thin magnetic oxide
coating on a 130mm diameteraluminum substrate. This coating form-
ulation, integrated with the low load force/loW mass flying heads, per-
mits reliable contact start/stop operation.
Data on each
of the disc surfaces is read by one read/write head, each
of which accesses 153 tracks.
FIGURE 1.0
AIR FILTRATION SYSTEM
-SCRUBBING
FILTER
-5-
CASTING
DISC

FIGURE 2.0
SPINDLE HUB AIR FLOW
SCRUBBING
FILTER
BAROMETRIC
FILTER
SPINDLE
ASSEMBLY
FIGURE 3.0
POSITIONING MECHANISM
READIWRITE HEADS
E BLOCK
BALL BEARINGS
-6-
INTERRUPTER
TRK.0
BRACKET
OPTICAL
DEVICE
"-- CAPSTAN

3.0 Functional Operations
3.1 Power Sequencing (Figure 4.0)
DC ON
Plus 5 and +12 volts may be applied in any order; however, +12 volts
must be applied to start the spindle drive motor. A speed sense
circuit counts 512 disc revolutions before recalibrating the heads to
Track ~. For this recalibration to occur, the step input signal must be
inactive. TRACK
~, SEEK COMPLETE, and READY signals on the
interface will become true sequentially. The drive will not perform
read, write or seek functions until READY becomes true.
FIGURE 4.0
POWER
UP SEQUENCE
I--- 18 sec. Typical
DISC UP TO SPEED
(512 REVS COUNTED)
-TRACK 0
-READY
-SEEK COMPLETE
-DRIVE SELECT*
(*GATES READY,
TK 0, SEEK COMPLETE)
-7-
AUTO RECAll BRATE
I PERIOD
~ 5 sec. Maximum
~uPto16.67ms.
I
I
--: I~ 15ms. Maximum
I
I
I

3.2 Drive Selection
Drive selection occurs when one
of the DRIVE SELECT lines is
activated. Only the selected drive will respond
to the input signals,
and only that drive's output signals are then gated to the controller
interface
(See section 4.5 for exception).
3.3 Track Accessing
Read/write head positioning is accomplished by:
a) Deactivating WRITE GATE line.
b) Activating the appropriate DRIVE SELECT line.
c) Being in the READY condition with SEEK COMPLETE true.
d) Selecting the appropriate direction.
e) Pulsing the STEP line.
Each step pulse will cause the head to move either 1 track in
or 1
track out depending on the level
of the direction line. A low level on
the direction line will cause a seek inward toward the spindle, a high,
outward toward Track
0.
3.4 Head Selection
Any
of the heads can be selected by placing the head's binary
address on the Head Select lines.
3.5
Read Operation
Reading data from the disc is accomplished by:
a) Deactivating the WRITE GATE line.
b) Activating the appropriate DRIVE SELECT line.
c) Assuring the drive is READY.
d) Selecting the appropriate head.
3.6 Write Operation
Writing data onto the disc is accomplished by:
a) Activating the appropriate DRIVE SELECT line.
b) Assuring the drive is READY.
c) Selecting the appropriate head.
d) Ensuring no WRITE FAULT conditions exist.
e) Activating WRITE GATE and plaCing data on the WRITE
DATA line.
-8-

4.0 Electrical Interface
The ST506 interface can be divided into three categories:
1. Control Signals.
2. Data Signals.
3. DC Power.
All control lines are digital in nature (open collector TTL) and either
provide signals to the drive (input) or signals to the host (output) via
interface
connection J1/P1. The data transfer signals are differential
in nature and provide data either to (write) or from (read) the drive via
J2/P2 (Defined by EIA RS-422).
Tables I. through III. and Figures 5.0 through 7.0 show connector pin
assignments and interconnection of cabling between the host con-
troller and drives.
TABLE I.
J1/P1 CONNECTOR PIN ASSIGNMENTS
GND RTN
SIGNAL
PIN PIN SIGNAL NAME
1 2 -REDUCED WRITE CURRENT
3 4 RESERVED (HD SELECT
22)
5 6
-WRITE GATE
7 8 -SEEK COMPLETE
9
10
-TRACK Q)
11
12
-WRITE FAULT
13 14
-HEAD SELECT 2°
15 16
RESERVED (TO J2 PIN 7)
17
18
-HEAD SELECT 2'
19 20
-INDEX
21
22
-READY
23
24
-STEP
25 26
-DRIVE SELECT 1
27 28
-DRIVE SELECT 2
29
30
-DRIVE SELECT 3
31
32
-DRIVE SELECT 4
33
34 -DIRECTION IN
-9-

TABLE II.
J2/P2-CONNECTOR PIN ASSIGNMENT
GND RTN
SIGNAL
PIN PIN SIGNAL NAME
2 1 - DRIVE SELECTED
4 3 RESERVED
6 5 RESERVED
8 7 RESERVED
(TO J1 PIN 16)
9,10 RESERVED
12
11 GND
13 +MFM WRITE DATA
14 -
MFM WRITE DATA
16 15 GND
17 +MFM READ DATA
18 -MFM READ DATA
20 19 GND
TABLE III.
J3/P3 CONNECTOR PIN ASSIGNMENTS
GND RTN SIGNAL
PIN PIN DESCRIPTION
2 +12 Volts DC
3 4 + 5 Volts DC
-10-

HOST
SYSTEM
FIGURE 5.0
CONTROL SIGNALS
FLAT CABLE OR TWISTED PAIR
20 FEET MAXIMUM
-REDUCED WRITE CURRENT
r---
RESERVED (HD SELECT 22)-
- -WRITE GATE
~
~ -SEEK COMPLETE
~ -TRACK0
..-- -WRITE FAULT
r--- -HEAD SELECT 2°
..
r---
RESERVED (TO J2 PI N 7)
r--- -HEAD SELECT 2')
~ -INDEX
~ -READY
I--- -STEP
..
r-- -DRIVE SELECT 1
..
I---
-DRIVE SELECT 2
..
r-- -DRIVE SELECT 3
..
r---- -DRIVE SELECT 4
..
r--- -DIRECTION IN
..
-11-
ST506
1-
2
3-
4
5-
6
7-
8
9-
10
11 -
12 13
-
14 15
-
16 17
-
18
19 -
20
21 -
22
23-
24
25-
26
27-
28
29-
30
31-
32
33-
34

FIGURE 6.0
DATA SIGNALS
HOST FLAT CABLE OR TWISTED PAIR ST506
SYSTEM
20 FEET MAXIMUM
-DRIVE SELECTED 1
2-
RESERVED
~
3
4-
RESERVED 5
6-
RESERVED (TO J1 PIN 16)
7
8-
RESERVED 9
10
RESERVED
11-
12-
+ MFM WRITE DATA
..
13
-MFM WRITE DATA
..
14
GND
15-
16-
+ MFM READ DATA 17
-MFM READ DATA
-
18
GND
19-
20-
_L....
-'--
--
-12-

FIGURE 7.0
TYPICAL CONNECTION, 4 DRIVE SYSTEM
HOST
CONTROL
h r
I-l
-L
Jl
r
J2
DRIVE #1
L
r
J3
L
J4
Y
CONTROLLER r
~
Jl
r
J2
DRIVE #2
L
r
J3
L
J4
Y
r
~
Jl
r
~
J2
DRIVE #3
~
r
~
L
J3
h
f-J
J4
h Y
DATA
~
SEPARATOR r
~
Jl
r
J2
DRIVE #4
I-J L
r
J3
L
J4
Y
DC VOLTAGES -
,-
FRAMEGND
·13·