Shugart SA810 User manual

TABLE OF CONTENTS
Page
TABLEOFCONTENTS .............................................................. i
LIST OF FIGURES
................................................................... iii
LIST OF TABLES .................................................................... iv
ABBREVIATIONS/MNEMONICS ....................................................... iv
SECTION I INTRODUCTION ......................................................... 1-1
1. 1 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Specifications Summary
................................................ 1-1
1.2.1 Performance Specifications
........................................ 1,.-1
1.2.2 Functional Specifications ......................................... 1-2
1.2.3 Physical Specifications ........................................... 1-2
1.2.4 Reliability Specifications .......................................... 1-3
1.3 Functional Characteristics
............................................... 1-3
1.3.1 Electronics
.................................................... 1-3
1.3.2 Drive Mechanism ............................................... 1-4
1.3.3 Positioning Mechanism ........................................... 1-4
1.3.4 Read/Write Heads .............................................. 1-4
1.3.5 Recording Formats .............................................. 1-4
1.4 Functional Operations ................................................. 1-4
1.4.1 Power Sequencing
.............................................. 1-4
1.4.2 Drive Selection ................................................. 1-4
1.4.3 Motor On ..................................................... 1-4
1.4.4 Track Accessing ................................................ 1-6
1.4.5 Step Out ..................................................... 1-6
1.4.6 Step In ....................................................... 1-6
1.4.7 Side Selection (SA860 Only) .... _. __ .............................. 1-7
1.4.8 Read Operation ............................... ' ................. 1-8
1.4.9 Write Operation ........................ " ....................... 1-9
1.4.10 Sequence of Events ............................................ 1-10
SECTION
II ELECTRICAL INTERFACE ................................................. 2-1
2.1 Introduction
........................................................ 2-1
2.2 Signal Interface ...................................................... 2-1
2.2.1 InputLines
................................................... 2-1
2.2.2 Input Line Termination .......................................... 2-3
2.2.3 Drive Select 1-4 ................................................ 2-3
2.2.4 Side Select (SA860 Only) ........................................ 2-3
2.2.5 Direction Select ................................................ 2-4
2.2.6 Step ........................................................ 2-4
2.2.7 Write Gate .................................................... 2-4
2.2.8 Write Data .................................................... 2-4
2.2.9 Motor On (Alternate Input) ....................................... 2-4
2.2.10 In Use (Alternate Input) ......................................... 2-4
2.2.11 External Write Current Switch (Alternate Input) ........................ 2-4
2.2.12 Output Lines ...................... : .......................... 2-5
2.2.13 . Track 00 .................................................... 2-5
2.2.14 Index ...................................................... 2-5
2.2.15 Sector (Hard Sector Only) ....................................... 2-5
2.2.16 Ready ...................................................... 2-5
2.2.17 Read Data ................................................... 2-6
2.2.18 Sep Data .................................................... 2-6
2.2.19 SepClock ................................................... 2-6
2.2.20 Write Protect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.2.21 True Ready
.................................................. 2-6
2.2.22 Disk Change (Optional Output) .............................. ; .... 2-6
2.2.23 Two Sided (Optional Output) ..................................... 2-6
2.2.24 Alternate I/O Pins ............................................. 2-6

TABLE OF CONTENTS (CONT.)
2.3 Power Interface ...................................................... 2-6
2.4 Frame Grounding .................................................... 2-7
SECTION III PHYSICAL INTERFACE .................................................. 3-1
3.1 Introduction ........................................................ 3-1
3.2 Jl/Pl Connector ................................................... 3-1
3.3 J2/P2 Connector .................................................. 3-2
SECTION IV DRIVE PHYSICAL SPECIFICATIONS ....................................... 4-1
4.1 Introduction ........................................................ 4-1
4.2 Mechanical Dimensions ........................................... ~ ... 4-1
4.3 Mounting .......................................................... 4-1
4.4 Stacking Dual Drives ................................................. 4-1
SECTION V ERROR RECOVERY ..................................................... 5-1
5.1 Write Errors ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.2 Read Errors ........................................................ 5-1
5.3 Seek Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
SECTION VI RECORDING FORMAT ................................................... 6-1
6.1 Recording Format (Single Density) ....................................... 6-1
6.1.1 Bit Cell ..................................................... 6-1
6.1.2 Byte ....................................................... 6-2
6.2 Recording Format (Double Density) ...................................... 6-2
6.3 Rules of Encoding ................................................... 6-3
6.3.1 FM Encoding ................................................. 6-3
6.3.2 MFM Encoding ............................................... 6-3
6.4 Tracks and Recording Formats .......................................... 6-3
6.4.1 Tracks ...................................................... 6-3
6.4.2 Track Format ................................................. 6-3
6.4.3 Hard Sector Recording Format .................................... 6-3
6.4.4 Soft Sector Recording Format .................................... 6-3
6.4.5 Typical Track Index Format ...................................... 6-3
SECTION VII CUSTOMER INSTALLABLE OPTIONS ...................................... 7-1
7.1 Introduction ....................................................... 7-1
7.2 External Write Current Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
7.3 Two-Sided Status (Optional Output SA860 only) ........................... 7-5
7.4 Disk Change (Optional Output) ......................................... 7-5
7.5 Side Selection Using Direction Select (SA860 only) .......................... 7-6
7.6 Side Selection Using Drive Select (SA860 only) ............................. 7-6
7.7 In Use Alternate Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7
7.8 Motor On Without Selecting Drive ....................................... 7-7
7.9 Motor On by Optional Motor On and Drive Select ........................... 7-8
7.10 Motor Off Delay .................................................... 7-8
7.11 Radial Ready ..................................................... 7-9
7.12 Stepper Power Down ............................................... 7-10
7.13 Write Protect Optional Use ........................................... 7-10
SECTION VIII OPERATION PROCEDURES ............................................. 8-1
8.1 Introduction ...................................................... 8-1
8.2 Diskette Loading and Handling ........................................ 8-1
8.2.1 Write Protect: Shugart 8-Inch Diskettes ........................... 8-2
8.2.2 Write Protect: IBM Diskettes ................................... 8-2
SECTION IX PACKAGING; .......................................................... 9-1
APPENDIX A MACHINE LEVEL CODE INFORMATION .................................... A-I
APPENDIX B ORDERING INFORMATION .............................................. B-1
ii

Figure
Number
Title
LIST OF FIGURES
Page
1-1 SA810/860 Half-Height Floppy Disk Drive ................................. 1-0
1-2 SA810/860 Functional Diagram ........... . ............................ 1-5
1-3 Track Access Timing, Standard Seek
...................................... 1-6
1-4 Track Access Timing, Buffered
Seek ....................................... 1-7
1-5 Read Initiate Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1-6 Read Signal Timing
(FM Encoding) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
1-7
FM and MFM Code Comparisons ......................................... 1-8
1-8 Write Initiate Timing
................................................... 1-9
1-9
SA810/860 General Control and Data Timing Requirements .................... 1-10
2-1 SA810/860 Interface Connections ........................................ 2-2
2-2 Interface Signal Driver/Receiver
.......................................... 2-3
2-3 Index Timing
........................................................ 2-5
2-4 SectorTiming
....................................................... 2-5
2-5
DC PowerProfile ..................................................... 2-7
3-1 Interface
Connectors- Physical Locations .................................. 3-1
3-2
Jl Connector Dimensions .............................................. 3-2
3-3
J2/P2 Connector ..................................................... 3-2
4-1 Physical Dimensions
................................................... 4-2
6-1 Data Pattern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6-2
Bit Cell ............................................................. 6-1
6-3 Byte
............................................................... 6-1
6-4 Data Bytes
.......................................................... 6-2
6-5
FM and MFM Encoding ................................................ 6-4
6-6 .
SA810/860 Hard Sector Recording Format (FM) ............................. 6-4
6-7
MFM Track Format Comparison .......................................... 6-5
6-8
MFM Index Pre Address Mark ........................................... 6-6
6-9 Index Address Mark
FM ................................................ 6-6
6-10 MFM Index Address Mark .............................................. 6-7
6-11
10 Address Mark FM .................................................. 6-7
6-12
MFM 10 Address Mark ................................................. 6-7
6-13
MFM Pre ID/Data Address Mark ......................................... 6-8
6-14 Data Address Mark FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
6-15 Deleted Data Address Mark
FM .......................................... 6-8
6-16
MFM Data Address Mark ............................................... 6-9
6-17
MFM Deleted Data Address Mark ......................................... 6-9
7
-1 PCB Component Locations (P /N 25227 and 25247) . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
7-2 PCB
Component Locations (P /N 25249) ................................... 7-4
7-3 External Write Current Option
........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
7-4
Disk Change Timing ................................................... 7-5
7-5
Disk Change Circuit ................................................... 7-6
7-6 Side Selection Using Direction Select
...................................... 7-6
7-7 Side Selection Using Drive Select
......................................... 7-7
7-8 Motor On Without Selecting Drive Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
7-9 Motor On by Opt. Motor
On and Drive Select Circuit ........................... 7-9
7-10 Radial Ready Circuit. .................................................. 7-10
7-11 Write Protect Circuit ................................................... 7-10
8-1 Loading the SA810/860 ............................................... 8-1
8-2 Diskette Write Protect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
8-3 Write Protect Notch Specifications
........................................ 8-2
9-1
SA810/860 Packaging ................................................ 9-1
9-2 Pallet Loading
....................................................... 9-2
iii

LIST OF TABLES
Table
Number Title Page
2-1 DC Power Requirements ............................................... 2-7
3-1 Recommended
Jl Connectors ........................................... 3-2
7-1 Customer
Cut/Add Trace Options ........................................ 7-2
A-I Machine Level Code Information ......................................... A-I
B-1 Ordering Information .................................................. B-1
ABBREVIATIONS/ MNEMONICS
AM Address Mark
MFM
Modified FM
CRC Cyclic Redundancy Check
MLC
Machine Level Code
CRT Cathode-ray Tube
PCB
Printed Circuit Board
DS Drive Select PLL Phase Locked Loop
FM Frequency Modulation SEP Separated
10 Index
VFO
Variable Frequency Oscillator
LED Light Emitting Diode
WG Write Gate
ABOUT THIS MANUAL
This manual (P /N 39216-2) supersedes all earlier manuals. All earlier editions may be discarded.
While every effort has been made to ensure that the information provided herein
is correct, please notify us in the
event of an error or inconsistency. Direct any comments on the form at the back of this manual to:
Shugart
Technical Publications
475 Oakmead Parkway
Sunnyvale, CA 94086
[phone]
iv

FIGURE 1.1. SA810/860 HALF·HEIGHT FLOPPY DISK DRIVE
1·0

1.1 GENERAL DESCRIPTION
SECTION I
INTRODUCTION
The compact SA810 single-sided and SA860 double-sided half-height 8-inch floppy disk drives offer a reliable, low
cost, high performance solution for OEM data storage applications which require maximum capacity in
the smallest
space possible. The
SA810/860 drives are half the height of the Shugart SA801 floppy disk drive, fit in comfor-
tably with a CRT, require
no ac voltage, and offer up to 1.6 megabytes of unformatted capacity.
The SA810/860 offers the follOWing standard features:
a. Half-height sizing: 2.31 in. (59 mm) high by 8.55 in. (217 mm) wide by 12.00 in. (305 mm) deep
b. Interface and media compatibility with Shugart SA801/851 disk drives
c. Low
heat dissipation
d. Fast access time
{3 ms track to track}
e. Quiet operation
f. Low media wear due to low mass head
g. Rapid start dc drive motor--Iess than one revolution {eliminates ac requirements}
h. Phase-Locked Loop Crystal Referenced Motor
Speed Control
i. Media compatible with SA801/851 plus IBM 3740
j. Single or double density
k. 0.8/1.6M Bytes (unformatted capacity)
1. Write protect and programmable door lock for improved data security
m. Internal write current switching
n. TRUE READY alerts the system that the drive
is ready to send or receive data
o. Buffered seek
p. Single or multiple drive dc Motor
On control
q. Multiple jumper options
r. Shugart's proprietary Bi-Compliant read/write heads with straddle erase elements
s. Extended reliability
t. Activity light
u. Solid die cast chassis
v. Light weight
w. Inline dc and I/O connectors
The SA810/860 provides the best solution to the user looking for a compact, low cost, and reliable 8-inch floppy
disk drive. The
SA810/860 is the most versatile disk drive on the market. This drive is backed by an engineering
department that
is recognized as the largest, most experienced group in the entire floppy industry. The SA810/860
is the ultimate solution for small business systems, intelligent terminals, personal computer systems, and program
storage equipment.
1.2 SPECIFICATIONS SUMMARY
1.2.1 Performance Specifications
Capacity
Unformatted
Per Disk
Per Surface
Per Track
SA810
Single/Double Density
400/800 k bytes
400/800 k bytes
5.2/10.4 k bytes
1-1
SA860
Single/Double Density
0.8/1.6 M bytes
400/800 k bytes
5.2/10.4 k bytes

IBM Format
(128 byte sectors)
Per Disk
Per Surface
Per Track
Transfer Rate
Latency (average)
Access Time
Track to Track
Settle Time
One Track Seek & Settle
Average (including settle)
Motor Start Time
Worst Case
Typical
SA810
Single/Double Density
250/500 k bytes
250/500 k bytes
3.3/6.66 k bytes
250/500 k bits/sec
83 ms
3 ms
13 ms
16 ms
89 ms
165 ms
120 ms
1.2.2 Functional Specifications
Rotational Speed
Recording Density
(inside track)
Flux Density
Track Density
Tracks
Index
Encoding Method
Media Requirements
Soft Sectored
32 Sector Hard Sectored
Alignment Diskette
360 rpm
3268/6536 bpi
6536 fci
48 tpi
77
1
FM/MFM
SA100/102
SAI01/103
SA120
1.2.3 Physical Specifications
Environmental Limits
Ambient Temperature:
Relative Humidity:
Maximum Wet Bulb:
DC Voltage Requirements:
Operating
50° to 115°F (9.9° to 46.1 °C)
20% to 80%
85 OF (29.4°C)
Storage
-8° to 122<?F (-22.2° to 50°C)
1% to 95%
no condensation
+ 24.
00 ± 2.4 V dc @ 1. 0 A typ, 1.7 A max., 100 mV ripple.
+5.00 ± 0.25 V de @ 0.7 A typ, 1.0 A max., 50 mV ripple.
NOTE
SA860
Single/Double Density
500/1000 k bytes
250/500 k bytes
3.3/6.6t) k bytes
250/500 k bits/sec
83 ms
3 ms
13 ms
16 ms
89 ms
165 ms
120 ms
360 rpm
3408/6816 bpi
6816 fci
48 tpi
154
1
FM/MFM
SA150
SA151
SA122
Shipping
-40° to 144°F (-40° to 62.2°C)
1% to 95%
no condensation
If the stepper motor is energized by the controller during the single motor start-up time, the drive will ex-
ceed the +
24 V de current specification of 1.7 A maximum. Under this condition, the current specifica-
tion
is 2.2 A maximum.
1-2

Mechanical Dimensions
Width =
8.55 in (217 mm)
Height =
2.31 in (59 mm)
Depth =
12.00 in (305 mm)
Weight =
7lbs (3 kg)
Mounting
Top loading
Diskette Horizontal Label
Up/Down
Diskette Vertical Label Left/Right
Power Dissipation:
10 watts (34 BTU/hr) Standby
28 watts (96 BTU/hr) Typical
50 watts (171 BTU/hr) Maximum
1.2.4 Reliability Specifications
Mean Time Between Failure: 10,000 Power On Hours under typical usage.
Preventive Maintenance: Not required.
Mean Time to Repair:
30 Minutes
Component Life: 5 years
Error Rates:
Soft Read Errors:
Hard Read Errors:
Seek Errors:
Media Life:
1
per 109 bits read
1
per 10
12
bits read
1 per 106 seeks
Passes per Track: 3.5 x 106
Insertions: 30,000 +
1.3 FUNCTIONAL CHARACTERISTICS
The 810/860 floppy disk drives consist of:
a. Read/Write
and Control Electronics
b. Drive Mechanism
c. Precision Track Positioning Mechanism
d. Read/Write
Head (s)
1.3.1 Electronics
The electronics are packaged on one PCB which contains:
a. Index Detector Circuits (Sector/Index for Hard Sectored Media)
b.
Head Position Actuator Driver
c. Read/Write Amplifier
and Transition Detector
d. Write Protect
e. Drive Select Circuits
f. Spindle Motor Control
g.
Data/Clock Separation Circuits (FM Only)
h. Drive Ready Detector Circuit
i. Drive True Ready Detector Circuit
j. Side Select Circuit (Used on SA860 only)
k. In Use and Door Lock Circuits
1. Internal and External Write Current Switching
m. Power On Reset Circuit
n. Activity LED
1-3

1.3.2 Drive Mechanism
The Head Positioning Actuator moves the read/write head{s} to the desired track on the diskette. The head{s} is
loaded onto the diskette when the door knob is closed. If no diskette is inserted when the door knob is closed, the
heads will not touch each other.
The dc drive motor under phase locked loop speed control (using an integral tachometer) rotates the spindle at 360
rpm. A contracting collet/spindle assembly provides precision media positioning and clamping to ensure data inter-
change. A diskette ejector places the diskette within reach of the operator when the diskette
is unclamped.
1.3.3 Positioning Mechanism
The read/write head assembly is accurately positioned through the use of a precision HeliCam V-groove lead
screw with a flat nutfollower which
is attached to the head carriage assembly. Precise track location is accomplished
as the lead screw
is rotated in discrete increments by a stepper motor.
1.3.4 Read/Write Heads
The proprietary head {s} is a single element ceramic read/ write head with straddle erase elements to provide erased
areas between data tracks. Thus, normal interchange tolerances between media
and drives will not degrade the
signal to noise ratio
and diskette interchangeability is ensured.
The read/write head{s) is mounted on a carriage which is located on precision carriage ways. The diskette is held in
a plane perpendicular to the read/write head (s) by a platen located on the base casting. This precise registration
assures perfect compliance with
the read/write head{s}. The read/write head{s} is in direct contact with the
diskette. The
head surfaces have been designed to obtain maximum signal transfer to and from the magnetic sur-
face of the diskette with minimum
head/diskette wear due to the low mass suspension system.
1.3.5 Recording Formats
The format of the data recorded on the diskette is totally a function of the host system. This format can be designed
around the user's application to take maximum advantage of the total available bits that can be written on anyone
track.
Figure 1-2 provides a functional diagram of the
SA810/860. For a detailed discussion of the various recording for-
mats, refer to Section
VI.
1.4 FUNCTIONAL OPERATIONS
1.4.1 Power Sequencing
Applying dc power to the SA810 or SA860 can be done in any sequence; however, during power up, the WRITE
"GATE line must be held inactive or at a high level. After application of dc power, a 90 ms delay should be introduc-
ed before a seek operation or before the control output signals are valid. After powering on, the initial position of
the read/write heads with respect to the data tracks on the media is indeterminant. In order to assure proper posi-
tioning of the read/write
heads after power on and internal write current SWitching at the proper track, a STEP
OUT operation should be performed until the TRACK 00 line becomes active (recalibrate).
1.4.2 Drive Selection
Drive selection occurs when the DRIVE SELECT line in the drive is activated. Only the drive with this line active
will respond to input lines or gate output lines. Under normal operation, the DRIVE SELECT line enables the input
and output lines, starts the spindle motor, locks the door, and lights the Activity LED on the front of the drive.
1.4.3 Motor On
In order for the host system to read or write data, the dc drive motor must be turned on. In the standard configura-
tion, this
is accomplished by activating the line DRIVE SELECT. A 165 ms delay must be introduced after ac-
tivating this line (or the TRUE READY line may be monitored) to allow the motor to
come up to speed before
reading
or writing can be accomplished. All motors in a daisy chain configuration can be turned on with the op-
tional MOTOR ON line or the spindle motor may be activated
when both MOTOR ON and DRIVE SELECT are
present. Refer to paragraphs
7.8 and 7.9.
1-4

READ DATA
-
SEP DATA (FM) READ WRITE
LOGIC
f.-
-.
PROTECT
SEP CLOCK (FM) ASSM
~
DRIVE SIDE
SELECT SELECT DISKETTE
WRITE DATA
..
.
WRITE GATE
-
WRITE
WRITE CURRENT (OPT) LOGIC STEPPER
_ WRITE PROTECT
ACTUATOR
H.
I
~ j
I'
R/WO
~
cJ,
R/W1
R/W HEAD
TRACK
SIDE ASSM.
.
40 SELECT POWER
ON
. ~
DOOR
RESET
\. MOTOR CLOSED
·SIDE SELECT
SWITCH
STEP
I
DIRECTION/ *SIDE SELECT (OPT.) INDEX/
DRIVE/*SIDE SELECT (OPT.) SECTOR
DETECTOR
MOTOR ON (HEAD LOAD) (OPT.L
IN USE (OPT.) t
.
TWO SIDED (OPT.)
CONTROL
TRACK 00 LOGIC
INDEX
IN USE
...
-p
LED
SECTOR
READY/TRUE READY (OPT.)
TRACK
-00
TRUE READY (OPT.)
...
~
-SENSOR
_ DISK CHANGE (OPT.)
ALTERNATE I/O (2 lines)
DOOR
LOCK
.
*SA860 ONLY
SOLENOID
FIGURE 1·2. SA810/860 FUNCTIONAL DIAGRAM 39216·02·A

In the standard configuration, the host system turns off the motor by deactivating the DRIVE SELECT line. This
should be
done if the drive has not received a new command within 2.6 seconds (16 revolutions of diskette) after
completing
the execution of a command. This will ensure maximum motor and media life. Also, the 2.6 second
delay function can be done by the drive by jumpering the optional Motor Off delay. Refer to paragraph 7.10.
1.4.4 Track Accessing
Seeking the read/write heads from one track to another is accomplished by:
a. Activating DRIVE SELECT line.
b. Selecting desired direction utilizing DIRECTION SELECT line.
c. WRITE GATE being inactive.
d. Pulsing
the STEP line.
Multiple track accessing
is accomplished by repeated pulsing of the STEP line until the desired number of steps
have
been input. Each pulse on the STEP line will cause the read/write heads to move one track either in or out
depending on the DIRECTION SELECT line. Head movement is initiated on the leading edge of the STEP pulse.
Pulses received at less than a 3 ms period, but greater than 15 p,S, will be stored in a buffer which will then issue step
commands to the drive stepper motor at a 3 ms pulse rate. Pulses received at greater than a 3 ms period will step
the drive at the same rate they are received. The first step begins upon receipt of the first step pulse.
1.4.5 Step Out
With the DIRECTION SELECT line at a plus logic level (2.5 V to 5.25 V), a pulse on the STEP line will cause the
read/write head(s) to move one track away from the center of the disk. The pulse(s) applied to the STEP line must
have
the timing characteristics shown in figure 1-3 or figure 1-4.
1.4.6 Step In
With the DIRECTION SELECT line at a minus logic level (0 V to 0.4 V), a pulse on the STEP line will cause the
read/write heads to move one track closer to the center of the disk. The pulse(s) applied to the STEP line must
have the timing characteristics shown
in figure 1-3 or figure 1-4.
DC POWER
-I--------------~u~-------------
DRIVE SELECT I
I
--------------~i~2------------------
DIRECTION SELECT ________ OUT
~
I IN i~
STEP
-I1--11'S ~ 1-
1
1'5 MIN
~~S _I 1-16 ms MIN -I r-
1
1'5 MIN
---------~ ~--
11'5 MI~ ~ ~ 3 ms MIN" -1
1---3 ms MIN"
*3 ms is the minimum frequency for a standard seek. Pulses received at less than a 3 ms frequency
will go into a buffered seek mode. See figure 1-4.
39216·03·A
FIGURE 1·3. TRACK ACCESS TIMING, STANDARD SEEK
1-6

DC POWER I
~ --------------~l~l---------------
DRIVE SELECT I
DIRECTION SELECT ___ 1 ___ _
~
--1~1:1 .s
r--- -
I
------_ ....... ' -- --
OUT
~----------------
STEP
90
ms
MIN
LJlJ
1 /ls MIN~
rI 15"s MIN" .~
r-2.~ ms MAX
~ 15/l8 MIN**
I 2.9 ms MAX"
* After the last step pulse has been issued the drive may be deselected. The drive ignores any
change to the DIRECTION SELECT line when no further step pulses are received. This frees the
controller to issue instructions to other drives while the first drive completes the step commands
stored in the buffer.
**Pulses received at less than a 3 ms period will be stored in a buffer which will then issue step com-
mands to the drive stepper motor at a 3 ms pulse rate. Pulses received at greater than a 3 ms per-
iod will step the drive at the same rate they are received. The first step begins upon receipt of the
first step pulse. 39216·31
FIGURE 1·4. TRACK ACCESS TIMING, BUFFERED SEEK
1.4.7 Side Selection (SA860 Only)
Head selection is controlled via the I/O signal line designated SIDE SELECT. A plus logic level on the SIDE
SELECT line selects the
read/write head on the side asurface of the diskette. A minus logic level selects the side 1
read/write head. When switching from one side to the other, a 100 JLS delay is required after SIDE SELECT
changes state before a read or write operation can be initiated. Figure 1-5shows the use of SIDE SELECT prior to a
read operation.
DC POWER
DRIVE SELECT
STEP
SIDE SELECT
(SA860 ONLY)
WRITE GATE
~~------------------------------~u~----------
I
'--------------------------------------------~l~~------------
.--------------------------------~l~~---------------
1-100 "s
-----------------------------~?~~-------------
VALID READ DATA ------------------
*Or when TRUE READY comes active. 39216-04
FIGURE 1·5. READ INITIATE TIMING
1-7

1.4.8 Read Operation
Reading data from the SA810/860 drive is accomplished by:
a. Activating DRIVE SELECT line.
b. Selecting
head (SA860 only).
c. WRITE GATE being inactive.
The timing relationships required to initiate a read sequence are shown in figure 1-5. These timing specifications are
required
in order to guarantee that the position of the read/write head has stabilized prior to reading. The timing of
READ DATA
(FM) is shown in figure 1-6.
READ DATA
SEP DATA
SEP CLOCK
A
I
LJ
I
B
I A
I
4.00 itS
NOM
U I
~ l.--200 ± 50 ns
I
U
~I ~200 ± 50ns
A B A
I U II
U U
A = LEADING EDGE OF BIT MAY BE ± 400 ns FROM ITS NOMINAL POSITION.
B = LEADING EDGE OF BIT MAY BE ± 200 ns FROM ITS NOMINAL POSITION ..
FIGURE 1·6. READ SIGNAL TIMING (FM ENCODING)
39216·05
The encoding scheme of the recorded data can be FM or MFM. The first of these, FM, provides single-density
recording.
The superior efficiency of MFM permits the bit cell period to be half that of the FM code, thereby pro-
viding double-density recording. Differences
among FM and MFM encoding are concerned with the use of clock
bits
in the write data stream.
FM encoding rules specify a clock bit at the start of every bit cell. MFM encoding rules allow clock bits to be omitted
from
some bit cells, when either the preceding bit cell or the current bit cell contains a data bit. See figure 1-7.
a o o o
BIT
CELLS
D D D D D
FM
--.. 2F
~
MFM
FIGURE 1·7. FM AND MFM CODE COMPARISONS
1-8

In both of these encoding schemes, clock bits are written at the start of their respective bit cells and data bits at the
center of their bit cells.
The timing of the read signals, READ DATA, SEPARATED DATA, and SEPARATED CLOCK are shown in
figure 1-6 (FM encoding).
In the standard SA810/860, data separation of FM data is performed by the drive electronics. Data bits are
presented to the controller
on the SEP DATA line and clock bits are presented on the SEP CLOCK line. In systems
using
MFM encoding, data separation is performed outside the drive. In such cases, the READ DATA line carries
both clock bits
and data bits. Separation of MFM encoded read data should be controlled by a phase-locked loop
circuit.
For additional information regarding the use of
MFM encoding, refer to paragraph 6.2.
1.4.9 Write Operation
Writing data to the SA810/860 is accomplished by:
a. Activating DRIVE SELECT line.
b. Selecting
head.
c. Activating WRITE GATE line.
d. Pulsing WRITE DATA line with data to be written.
e. Head current switching.
The timing relationships required to initiate a write data sequence are shown in figure 1-8. These timing specifica-
tions are required in
order to guarantee that the read/write head position has stabilized prior to writing.
Write data encoding can be
FM or MFM. If MFM is used, the write data should be precompensated to counter the
effects of bit shift.
The amount and direction of compensation required for any given bit in the data strea'm depends
on the pattern it forms with nearby bits.
For more details regarding data encoding and formatting for
SA810/860 drives, refer to Section VI.
DC POWER
DRIVE
SELECT
STEP
I-- 90 ms MIN -----I
I I
1-
'65
ms MIN1
-I----.U
r-9~~S~--1 --------11 r100 I(S MIN
SIDE SELECT
~ I !
(SA860 ONLY)
WRITE GATE
16 ms MIN' r-i
I_--------------~
-I i-
4
'SMIN
-------..U U
WRITE DATA u
* Or when TRUE READY comes active
FIGURE 1·8. WRITE INITIATE TIMING
1-9
39216·07·A

1.4.10 Sequence Of Events
The timing diagram shown in figure 1-9 illustrates the necessary sequence of events with associated timing restric-
tions for
proper operation.
DC POWER
VALID CONTROL
~90ms MIN
AND OUTPUT SIGNALS 90 I
DRIVE SELECT
SIDE SELECT
(SA860 ONL
Y)
DIRECTION
SELECT
STEP
TRUE READY
WRITE GATE
WRITE DATA
VALID READ
DATA
SIGNAL
ms
MIN
----.
I I
I I
I
ss
~500mSMAX
*r--, *,--'
, , ,I
1_ 100 ;.-- ~ I ~\~ ___ ...L.' ~I ---\:~\~-------
r- MAX
SS ~S
I
1
1 s I {m~t 1 S~ _II T-- ..... l---\S\oS---------
M)N ~ r- HMIN~ Mf~ .... ~ 1 /ls MIN ~S
90 m~ II Ln 1 /ls I tn.J~----\'t-----
MIN .. ~ ~ ~NOTE2~16ms
NOTE 2~ -.J t....MIN 16 ms-.i l.-
II
~6 m~1 MI~r------J --·L ~ ----"S'"S---
II~IN r-16 ms
I I I
SS I MIN I
...
I.. I I 100 •• MIN ;; ~
J.oI-f----~----''--- NOTE 1 ~ r- 4 /ls MIN I
~ L16 ~. lnf1ru~I--
1- MIN ~ r-
50 /ls MIN
---:"'-~-NO-TE l=tnfWJ \~
NOTE 1: 165 ms minimum delay must be introduced after DRIVE SELECT to allow time for the dc motor to
reach 360 rpm or the optional TRUE READY line must be monitored.
NOTE 2: If performing standard seeks, the minimum frequency is 3 ms between steps. If utilizing the drive in
the buffered seek mode of operation the frequency shall be 15 p..s to 2.9 ms between pulses.
* After the last step pulse has been issued, the drive may be deselected. The drive ignores any change to
the DIRECTION SELECT line when no further step pulses are received. This frees the controller to
issue instructions to other drives while the first drive completes the step commands stored in the
buffer.
39216·08·A
FIGURE 1·9. SA810/860 GENERAL CONTROL AND DATA TIMING REQUIREMENTS
1-10

SECTION II
ELECTRICAL INTERFACE
2.1 INTRODUCTION
The interface of the SA810/860 Diskette Drive can be divided into two categories:
a. Signal
b. Power
The following paragraphs provide the electrical definition for each line. See figure 2-1 for all interface connections.
2.2 SIGNAL INTERFACE
The signal interface consists of two categories:
a. Control
b. Data Transfer
All lines in the signal interface are digital in nature and either provide signals to the drive (input), or provide signals
to the host (output), via interface connector
Pl/ J1.
2.2.1 Input Lines
There are twelve signal input lines. Nine are standard and three are user installable options (refer to Section VII).
The input signals are of three types. those intended to be multiplexed
in a multiple drive system, those not intended
to be multiplexed.
and those which will perform the multiplexing.
The input signals which are intended to do the multiplexing are:
a. DRIVE SELECT 1
b. DRIVE SELECT 2
c. DRIVE SELECT 3
d. DRIVE SELECT 4
The input signals to be multiplexed are:
a. SIDE SELECT
b. DIRECTION SELECT
c. STEP
d. WRITE GATE
e. WRITE DATA
The input signals which are not multiplexed are:
a. MOTOR ON
(May be optionally multiplexed. Refer to paragraph 7.9.)
b. IN USE
c. EXTERNAL WRITE CURRENT SWITCH
2-1

HOST
~
DC -~.fT.
GND -=- FRAME GND
MAX FEET
10 FT FLAT RIBBON OR
20 FT TWISTED PAIR
EXTERNAL WRITE CURRENT SWITCHING'
TRUE READY'
TWO SIDED' +
DISK CHANGE'
SI DE SELECT' +
IN USE'
MOTOR ON' (HEAD LOAD)
INDEX
READY
SECTOR
DRIVE SELECT 1 (SIDE SELECT
OPT) +
DRIVE SELECT 2 (SIDE SELECT OPT) +
DRIVE SELECT 3 (SIDE SELECT OPT) +
DRIVE SELECT 4 (SIDE SELECT OPT) +
DIRECTION SELECT (SIDE SELECT OPT) +
STEP
WRITE DATA
WRITE GATE
TRACK
00
WRITE PROTECT
READ DATA
SEP DATA
SEP CLOCK
...... +5 V DC
X +5 V RETURN
......
"" +24 V DC
X+ 24 V RETURN
'"
TWISTED PAIR
'JUMPER ENABLED ALTERNATE I/O LINES.
+ SA860 ONLY
SA81
01860
J1
2 1
8 7
10
9
12
11
14 13
16
15
18 17
20
19
22
21
24
2:3
26 25
28 27
30 29
32
31
34
33
36 35
38 37
40
39
42
41
44
4"
46 45
48 47
50
49
3 J2 4
1 2
5
am
FIGURE 2·1. SA810/860 INTERFACE CONNECTIONS
2-2
~
-
39216·09

The input circuit lines have the following electrical specifications. See figure 2-2 for the recommended circuit.
True = Logical zero =
Vin ± 0.0 to + 0.4 V @ lin = 40 rnA (max)
False = Logical
one = Vin ± 2.5 to + 5.25 V @ lin = 250 f-tA (open)
Input Impedance =
220/330 ohms
MAX 10 FEET I
RIBBON OR 20
FEET TWISTED
PAIR
+5V
7414
39216·10
FIGURE 2·2. INTERFACE SIGNAL DRIVER/RECEIVER
2.2.2 Input Line Termination
The SA810/860 has been provided with a removable resistor pack for terminating the eight input lines.
In order for the drive to function properly, the last drive on the interface must have these eight lines terminated.
Termination of these lines can be accomplished
by either of two methods:
a. As shipped from the factory, the resistor pack
is installed in location U9. These packs can be
removed from all drives except the last one on the interface.
b. External termination may be used provided the terminator
is beyond the last drive. Each of the
lines should be terminated by using a 220/330 ohm, 1/4 watt resistor, pulled up to +5 V dc.
The same removable resistor pack is also prOVided for terminating the optional input lines.
2.2.3 Drive Select 1·4
DRIVE SELECT, when activated to a logical zero level, enables the multiplexed I/O lines, starts the spindle motor,
energizes the
stepper motor, locks the door, and lights the activity LED. In this mode of operation, only the drive
with this line active
will respond to the input lines and gate the output lines.
Four separate input lines, DRIVE SELECT 1, DRIVE SELECT 2, DRIVE SELECT 3,
and DRIVE SELECT 4, are
prOVided so that up to four drives may be multiplexed together
in a system and have separate DRIVE SELECT
lines. Traces DS1, DS2, DS3,
and DS4 have been prOVided to select which DRIVE SELECT line will activate the
interface signals for a unique drive. As shipped from the factory, a shorting plug
is installed on DSl. To select
another DRIVE SELECT line, this plug should be moved to the appropriate OS pin.
2.2.4 Side Select (SA860 Only)
This interface line defines which side of a two-sided diskette is used for reading or writing. An open circuit, or logical
one, selects the read/write head on the side 0 surface of the diskette. A short to ground, or logical zero, selects the
read/write head on the side 1 surface of the diskette. When switching from one head to the other, a 100 f-tS delay is
required before any read or write operation can be initiated.
Two optional methods of side selection are available
and can be implemented by the user through appropriate
jumper connections. These options are described
in paragraphs 7.5 and 7.6.
2-3