Seagate ST-506 User manual

·ST506 MICROWINCHESTER
OEM MANUAL
PRELIMINARY
APRIL 1.1 1981
·&agate Tec1moloyy

Page
4.0
Electrical
Interface
4.1
Control
Input Lines
16
4.1.1
Reduced Write
Current
17
4.1.2
Write Gate
17
4.1.3 Head Select 20
and 21
17
4.1.4
Direction
In
17
4.1.5
Step
17
4.1.6 Drive
Select
1-4 19
4.2 Control Output Lines
19
4.2.1
Seek
Complete
19
4.2.2
Track
~
19
4.2.3
write
Fault
19
4.2.4
Index
20
4.2.5
Ready
20
4.3 Data Transfer Lines
20
4.3.1
MFM write Data
21
4.3.2 ·MFM Read Data
23
4.3.3
Read/Write
Timing
23
4.4
Drive
Selected
24
4.5 CUstomer
Options
24
4.5.1 Radial Select
24
4.5.2
Defeat Reca1ibrate 24
4.5.3 Half Step
25
.5.0 Physical
Interface
26
5.1
Jl/Pl Connector -
Control Signals
27·
5.2
J2/P2 Connector -
Data Signals
28
ii

6.0
5.3
5.4
Physical
6.1
6.2
6.3
6.4
J3/P3 Connector - DC Power
J4/p4 Frame Ground Connector
Specifications
Mounting
Orientation
Mounting
Holes
Physical
Dimensions
Shipping Requirements
7.0
Track
Fonnat
7.1
7.2
7.3
7.4
7.5
7.6
Figures:
l.
2
3
4
5
6
7
8
9
10
Gap 1
Gap 2
Gap 3
Gap 4
Sector Interleaving
Defective Sector Flags
Air Fil.tration System
Positioning Mechanism
Power Up Sequence
Control Signals
Data Signals
Typical Connection, 4 Drive System
Control Receiver/Driver Combination
Step Mode T~ing
Index Timing
Data Line Driver/Receiver Combination
iii
. Page
28
30
30
30
30
30
30
33
31
31
35
35
35
35
5-6
7
9
13
14
15
16
18
20
21.

Figures (Continued)
11 Write Precompensation Patterns
12 Read/Write Data Timings
13 Connector Physical Locations
14 Jl Connector Dimensions
15 J2 Connector Dimensions
16 J3 Connector
17 Mounting Physical Dimensions
18 OVerall Physical Dimensions
19 Track Format As Shipped
20 "Al" Address Mark Byte
Tables
I Jl/Pl
Connector
pin
Assignments
II
J2/P2
Connector
pin
Assignments
III
P3 DC
Connector
Pin
Assignments
IV DC Power Requirements
iv
Page
22
23
26
27
28
28
31
32
34
35
11
12
12
29

1.0 Introduction
1.1 General Description:
The ST506 disc drive is a random access storage device with
two non-removable 5~ inch discs as storage media. Each disc
surface employs one movable head to service 153 data tracks.
The total formatted capacity of the four heads and surfaces
is 5 megabytes. (32 sectors per track, 256 bytes per sector,
612 tracks).
Low cost and unit reliability are achieved through the use
of a band actuator and open loop stepper head positioning
mechani'sm. The inherent simplicity of mechanical construction
and electronic controls allows maintenance free operation
throughout the life of the drive. Both Electronic PCB's
are mounted outside HDA for field serviceability.
Mechanical and contamination protection for the heads,
actuator and discs are provided by an impact resistant
aluminum enclosure. A self contained recirculating system
supplies clean air through a 0.3 micron filter. A second
port in the filter assembly allows pressure equalization
with ambient air 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 yields a very low temperature rise within
the enclosure, providing 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 electrical interface is similar to the Shugart
Associates SAlOOO family of 8 inch fixed disc drives. The
ST506 size and mounting is identical to the industry standard
minifloppy disc drives and uses the same DC voltage and
connector. No AC power is required.
Key Features:
• storage Capacity of 6.38 megabytes unformatted, 5.0
megabytes formatted as shipped.
• Winchester design reliability, 9.5 gram head load force,
19 micro-inch flying height.
• 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

•
170 millisecond random average access time, reducible to
95 ms via a simple software algorithm (See Section 4.5.3)
1.2 Specification Summary:
1.2.1
1.2.2
1.2.3
Physical Specifications:
Environmental Limits:
Ambient Temperature = 40
0
to l22
0F
(4
0
to SOOC)
Relative Humidity = 8 to SO%
Maximum Wet Bulb = 7SO non-condensing
Maximum Altitude = 10,000 feet
DC Power Requirements
+12V ~ 5%, 1.SAtypical, 4.SA at power on
+5V ~ 5%, 0.7A typica1# 1.0A maximum
+12V/+SV Maximum Ripple = 50mV P-P
Mechanical Dimensions:
Height
=
3.25
inches
Width
=
S.75
inches
Depth
=
S.OO
inches
Weight
=
4.2 1bs.
(1.9 kg)
Heat Dissipation - 25 watts typical
- 29 watts maximum'
Reliability Specifications:
MTBF = 11,000 POH, typical usage
PM = Not required
MTTR 30 minutes
Component Design Life = 5 years
Error Rates:
Soft read errors
*Hard read errors
Seek errors
= 1 per 10~~ bits read
= 1 per 10
6
bits read
= 1 per 10 seek
*Not recoverable within 16 re-tries.
Performance Specifications:
2

Capacity
1.2.4
Unformatted
Per Drive
Per Surface
Per Track. -
Formatted
Per Drive
Per Surface
Per Track
Per Sector
Sectors per Track
6.38 Megabytes
1.59 Megabytes
10416 Bytes
5.0 Megabytes
1.25 Megabytes
8192 Bytes
256 Bytes
32
Transfer Rate
5.0 Megabits per second
Access Time
Track to Track 3 ms
Average (Inc. Settle)l70 ms, reducible to 95 ms. (See Section 4.5.3)
Maximum (Inc. Settle)500 ms, reducible to 245 ms. ..
Settling Time 15 ms
Average Latency
Functional Specifications
Rotational speed
Recording density
Flux density
Track density
Cylinders
Tracks
R/W Heads
Disks
8.33ms
3600
7690
7690
255
153
612
4
2
rpm
+ 1%
bpi
max
fci
tpi
2.0 Functional Characteristics
2.1 General Operation
The ST506 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.
3

2.2 Read/Write and Control Electronics
Electronics
are packaged on two printed circuit boards.
The primary board to which power, control and data signals
are connected includes:
1. Index ~etection circuit.
2. Head position/actuator circuit.
3. Read/write circuits.
4. Drive up to speed circuit.
5. Head select circuit.
6. Write fault detection circuit.
7. Step motor drive circuit.
8. Drive select circuit.
9. Track zero detector circuit.
The second PCB., mounted to the baseplate under the primary
board derives. its power from the primary board and provides
power and speed control to the spindle drive motor.
2.3 Drive Mechanism
A Brushless DC drive motor rotates the spindle at 3600 rpm.
The spindle is driven directly with no belt or pulley being
used. The motor is thermally isolated from the baseplate to
minimize temperature rise in the sealed chamber containing
the heads and discs. The ~otor and spindle are dynamically
balanced to insure a low vibration level. A brake is used
to provide a fast stop to the spindle motor when power is
removed. The baseplate is shock mounted to minimize
transmissibility of vibration to the chassis or frame.
2.4 Air Filtration System (Figure 1)
The discs and read/write heads are fully enclosed in a module
using a integral recirculation air system with an absolute
filter which maintains a clean environment. Integral to the
filter is a port which also permits pressure equalization
with the ambient air without contaminate entry.
2.5 . Positioning Mechanism (Figure 2)
The read/write heads are mounted on a ball bearing supported
carriage which is positioned by a band actuator connected to
the stepper motor shaft. The stepper motor is thermally
isolated from the baseplate to minimize temperature rise in
the sealed chamber containing the heads and discs.
4

AIR fLOW
- SCRU,1313IN G
FtL TER
FIG IA
5
DISC

SCR US 131N G
F1LTER
/ . I3A R 010 ETR Ie
- FILTER ..
FIG \8
6
/
DISC
/
I
I
'-- SPINDLE
A
:: c ~ tv1 13 LY
~-' -

.1
-_.- READ/ WR' TE I-{EA 0 5
'\
\
3i~ L L 8 EAR IN cj 5 ...
r-- S T. =: p p ~ R ~1 0 T C R
i
I
."
TRK.O
BRACKET
CARRIAGE RODS
FIG 2.
7

2.6 Read/Write Heads and Discs
The recording media consists of a lubricated thin magnetic
oxide coating on a 130 mm diameter aluminum substrate.
This coating formulation, together with the low load force/
low mass Winchester type flying heads, permit reliable contact
start/stop operation.
Data on each of the four disc surfaces is read by one
read/write head, each of which accesses 153 tracks.
3.0 Functional Operations
3.1 Power Sequencing (Figure 3)-
+5 and +12 volts may be applied in any order. +12 volts
must be applied to start the spindle drive motor. A speed
sense circuit counts 512 disc revolutions. After 512
revolutions, the heads will automatically recalibrate to
track~. (See Section 4.5.2 for exception). 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 p~rform
read & write or seek functions until READY becomes true.
3.2 Drive Selection
Drive selection occurs when one of the drive select lines
are activated. Only the drive selected will respond to
the input signals, and only that drive's, output signals
are then gated to the controller interface. (See Section
4.5.1 for exception) .
3.3 Track Accessing
Read/write head positioning is accomplished by:
a) Deactivating write gate.
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 heads to move either 1
track in or 1 track out depending on the level of the
8

DC ON
DISC UP TO SPEED
.(512 REVS COUNTED
X
-TRACK ~
-READY
FIGURE 3
POWER UP SEQUENCE
I
.~ 15 sec. Typical
AUTO RECALIBRATE
PERIOD
Up to 16.66 ms.
lSms max. ~ '---
x------------------------------~'----~l
-: .SEEK COMPLETE t '-. _________ ..,~
-DRIVEX-SE-L-E-C-T-·-----------I
(*GATES READY, TK ~, SEEK COMPLETE)
9

Direction Line. A true on the Direction Line will cause
a seek inward toward the spindle; a false outward toward
track i' .
3.4 Head Selection. -
Any of the 4 heads can be selected by placing the pead's
binary address on the two Head Select Lines.
3.5 Read Operation
Reading data from the disk 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 disk is accomplished by:
a) Activating the appropriate Drive Select line.
b) Assuring that the drive is Rea~y.
c) Select~ng the proper head.
d) Insuring no write fault conditions exist.
e) Activating Write Gate and placing data on the
Write Data li~e.
4.0 Electrical Interface
The interface to the STS06 can be divided into three categories,
each of which are physically separated.
1. Control signals.
2. Data signals.
3. DC power.
10

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/Pl. 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-A)
Tables I through III and Figures 4 through 6 show connector
pin assignments and interconnection of cabling between -the host
controller and drives.
ST506 DRIVE INTERFACE
TABLE I J1/Pl CONNECTOR PIN ASSIGNMENT
GND RTN
SIGNAL
PIN PIN
SIGNAL NAME
1 2 -
REDUCED WRITE CURRENT
3 4
RESERVED(Head 22
in future
5 6
-. WRITE GATE
7 8 -
SEEK COMPLETE·
9
10
- TRACK f&
11
12 -
\-lRITE FAULT
13 14 -
HBAD SELECT 20
15 16
RESERVED (TO J2
PIN 7)
17
18 -
HEAD SELECT 21
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
11
products)

STS06 DRIVE INTERFACE
TABLE II J2/P2 CONNECTOR PIN ASSIGNMENT
GND RTN
SIGNAL
PIN
PIN
SIGNAL NAME
2 1 -DRIVE SELECTED
4 3
RESERVED
6 5 SPARE
8 7
RESERVED
(TO J1 PIN 16)
9,10
SPARE
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
VOLTAGE
GROUND
PIN
1 +12V VOLTS
DC
PIN
2 +12V VOLT
RETURN
PIN
4 +5V
VOLTS DC
PIN
3 +5V
VOLT RETURN
TABLE III
P3 - DC CONNECTOR PIN ASSIGNMENTS
12

HOST SYSTEM
~
_.
~
-
-
-
It..
It.
L-
--
~
It.
-
It..
"
...
X
-
"
X
'""
-==-
DC GNO
m 6
FRAME GNO
ST506 DRIVE INTERFACE
FIGURE
4: CONTROL SIGNALS
J2/P2 NOT SHOWN
FLAT RIBBON OR
TWISTED PAIR MAX 20 FEET
-
REDUCED WRITE CURRENT
RESERVED
(HEAD
22)
- WRITE GATE
- SEEK COMPLETE
- TRACK f6
- WRITE FAULT
- HEAD SELECT 20
RESERVED (TO J2 PIN 7)
- HEAD SELECT
21
- INDEX
- READY
-STEP
-DRIVE SELECT 1
-DRIVE SELECT 2
-DRIVE SELECT 3
-DRIVE SELECT 4
-DIRECTION
IN
+ SVDC
+ SV RETURN
+ 12VDC
+ 12V RETURN
-
-
-
.-
-
-
--
-
--
-
--
-
-
-
--
-
-
.-
-
-
-
---
--
-
~
TWISTED PAIR
(20 GA or
larger)
13
,
ST 500
1-
2
3~.
4
S~.
6
7---U
8
9--0
10
11--0
12
13 _____ ~
14
1S~~
16
17---0
18
19--H
Jl/Pl
20
21~~
2~
23---0
24
2S~.
26
27--U
28
29~.
30
31~~
32
33----4~
34
-=-=
4
3
J3/P3
1
2
-...l.-
FRAME GROUND
IIIII
J4/P4

HOST SYSTEM
-
-
-
-
-
-
-
-
..
-==-
-
FIGURE 5: DATA SIGNALS
FLAT CABLE OR TWISTED PAIR
20 FEET HAXIMUM
-DRIVE SELECTED
RESERVED
SPARE
RESERVED
(TO J1
PIN 16)
SPARE
SPARE
+ MFM WRITE
DATA
- MFM WRITE
DATA
GND
+ MFM READ
DATA
- MFM
READ
DATA
GND
14
ST 506
1
2-
3 4
--0
5 6
---0
7
8--·U
9
10
11 ____U
12 ----4.
-
13
-
J2/P2
-14
--
·15 --oH
16 --0
17 -
18
..
19 __ 0
20 ~~
-==
..
-

FIGURE 6: TYPICAL CONNECTION, 4 DRIVE SYSTEM
HOST
,
CONTROL
r
.J
L
J1
DRIVE
r
l-
J2
#1
r-
J3
~
J4
Lf
CONTROLLER
r
J1
1-
r
J2
DRIVE
L-
#2
r
J3
1-
J4
Lf
r
J1
L DRIVE
r-
J2 #3
L
r
J3
-
1-
,
.J
J4
DATA
L r
Lf·
.J
SEPARATOR
,
..I
r
J1
"L
.,
r ,DRIVE
~
L.
J2
#4
r
J3
1-
J4
•
Lf
DC VOLTAGES
(RADIAL)
FRAME GND
15

4.1 Control Input Lines
The control input signals are of two types: those to
be multiplexed in a multiple drive system and those
intended to do.the multiplexing. The control input
signals to be multiplexed are REDUCED WRIIE CURRENT,
WRITE
GATE, HEAD SELECT 20, HEAD SELECT 2 ; STEP and
DIRECTION IN. The signal to do the multiplexing 1S
DRIVE SELECT l, DRIVE SELECT 2, DRIVE SELECT 3 or
DRIVE SELECT 4.
The input lines have the following electrical specifica-
tions. Refer to Figure for the recommended circuit.
TRUE:
O.OVDC to 0.4VDC @ I = -40 rnA (max)
FALSE:
2.SVDC to S. 2SVDC @ I = + 250 pA (open)
FIGURE 7:
CONTROL SIGNALS DRIVER/RECEIVER COMBINATION
+sv
220.n
7438
~- 20 FT (f.1AX)-.....-t
330.0.
16