Shugart SA860 User manual

This Document was scanned and
contributed by:
Barry A. Watzman
[Note that an extra section on “jumpers” has been added at the end of
the document. This was not originally in the service manual and was
taken from the OEM manual.]

.:
TABLE OF CONTENTS
TABLE OF CONTENTS i
LIST OF FIGURES. . iii
LIST OF TABLES iii
ABBREVIATIONS MNEMONICS iv
SECTION IINTRODUCTION 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 1-3
1.3.3 Positioning Mechanism 1-4
1.3.4 Read/Write Heads 1-4
1.3.5 Recording Formats 1-4
1.4 FunctionalOperations 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 (SA8600nly) 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 Input Lines 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) 2-7
2.2.24 Alternate I/O Pins 2-7

TABLE OF CONTENTS (CONT.)
2.3 Power Interface 2-7
2.4 Frame Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
SECTION
III PHYSICAL INTERFACE . . . . . . . . 3-1
3.1
Introduction..... . . . . . . . . . . . . . . . .. ,3-1
3.2 J1/P1 Connector , . . . . . . . . . . . . . . . . 3-1
3.3 J2/P2 Connector 3-2
SECTION IV THEORY OF OPERATIONS , , 4-1
4.1 GeneraIOperations 4-1
4.2 Read/Write Operations 4-1
4.3 Read/Write Head , ' ' 4-3
4.4 Write Circuit Operation 4-4
4.5 Read Circuit Operation 4-5
4.6 Drive Motor Control 4-6
4.7 Track Accessing , , , , . 4-6
4.7.1 Stepping 4-6
4.7.2 Carriage Actuator 4-6
4.7.3 Actuator Control Logic. , , , 4-7
4.7.4 Track Zero Indicator 4-9
SECTION VMAINTENANCE, ,5-1
5.1 Maintenance Equipment 5-1
5.1.1 Alignment Diskette .. ,5-1
5.1.2
SA809 Exerciser ,...................................... 5-1
5.1.3 Special Tools 5-1
5.2 Diagnostic Techniques 5-2
5.2.1 Soft Error Detection and Correction 5-2
5.2.2 Write Errors 5-2
5.2.3 Read Errors 5-2
5.2.4 Seek Errors 5-2
5.3 Trouble-Shooting , , 5-2
5.4 Adjustments 5-5
5.4.1 Side 1Downstop Adjustment (SA860 Only) 5-5
5.4.2 Head Radial Alignment ,. 5-5
5.4.3 Read/Write Head(s) Azimuth Check 5-7
5.4.4 Head Amplitude Check 5-8
5.4.5 Track 00 Detector Assembly 5-8
5.4.6 Track 00 Carriage Limiter 5-8
5.4.7 Index Sector Timing 5-8
5.4.8 Door Lock , , , 5-9·
5.4.9 Ejector/Bail 5-10
5.4.10 Stepper Motor ,5-11
5.5 Removals and Replacements 5-12
5.5.1 Faceplate and Door Knob , , 5-12
5.5.2 Drive Motor Assembly 5-12
5.5.3 Top Plate Assembly 5-12
5.5.4 Spindle Hub Assembly , , , 5-13
5.5.5 PCB Assembly 5-14
5.5.6 Door Lock Assembly .5-14
5.5.7 Side 1Arm Assembly (SA8600nly) ,.......... .5-14
5.5.8 Head and Carriage Assembly 5-14
5.5.9 Clamp Hub Assembly 5-15
5.5.10 Bail Assembly , . . . . . . . . . . . . 5-15
5.5.11 Track 00 Detector 5-15
5.5.12 Index/Sector LED Assembly . 5-15
5.5.13 Index/Sector Detector Assembly . .. 5-16
ii

TABLE OF CONTENTS (CONT.)
5.5.14 Write Protect Detector 5-16
5.5.15 Ejector Assembly 5-16
5.5.16 Door Switch 5-16
5.6 Recommended Incoming Receiving Inspection 5-17
5.6.1 Test Equipment 5-17
5.6.2 Procedure 5-17
SECTION
VI SCHEMATIC DIAGRAMS 6-1
SECTION
VII ILLUSTRATED PARTS CATALOG 7-1
7. 1
Description........................................................ 7-1
7.2 Indented Level 7-1
7.3 Quantity Per Level 7-1
7.4 Recommended Spare Parts Stocking Guide 7-27
LIST OF FIGURES
Figure Title
Page
1-1 SA81O/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 1-9
1-8 Write Initiate Timing 1-9
1-9
SA81O/860 General Control and Data Timing Requirements 1-10
2-1
SA81O/860 Interface Connections 2-2
2-2 Input Line Termination 2-3
2-3 Index Timing 2-5
2-4 Sector Timing 2-5
2-5 DC Power Profile 2-7
3-1 Interface Connectors -Physical Locations 3-1
3-2
J1 Connector Dimensions 3-2
3-3 J2/P2 Connector 3-2
4-1 Byte 4-2
4-2 Basic
Read/Write Head 4-2
4-3 Recorded
Bit 4-2
4-4 Reading a Bit 4-3
4-5 IF and 2F Recording Flux and Pulse Relationship 4-3
4-6 Read/Write Heads 4-4
4-7 Write Circuit Functional Diagram 4-5
4-8 Read Circuit Functional Diagram 4-6
4-9 Drive Motor Control 4-6
4-10 Actuator Control Logic 4-7
4-11 Track
00 4-7
4-12 Track 01 4-8
4-13 Track
02 4-8
iii

4-14
4-15
:) -1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
6-1
6-2
6-3
6-4
6-5
7-1
7-2
7-3
7-4
7-5
7-6
LIST OF FIGURES (CONT.)
Track 03 .. __ __ 4-8
Stepper Timing _ _ __ .. ___ _ 4-9
Write Protect Inoperative _ _ .. __ .... _. _. _ _. . . . . . . . . _. _. __ . . 5-3
Diskette Not Rotating _ _ .. _ _ _ 5-4
Side 1Downstop Adjustment _ _ __ .. _ 5-5
Head Radial Alignment ... .. _ . _. _ .. _ . _ __ _. _ 5-6
Motor Plate Mounting Screws __ .. _. . __ . _. _ .. , _. 5-6
Azimuth Burst Patterns . . _. _. _ _ _ _ _ .. . . . . 5-7
Track 00 Carriage Limiter Clearance . _ __ . _. . . __ . _ _ .. 5-9
Door Lock Solenoid Clearance .. __ __ .. _. _ _ __ _. 5-9
Diskette Stop Clearance __ _ .. _. _. .. _ _. _ .. _. _ .. 5-10
Bail Assembly Adjustment . __ . _ _ . .. . _ __ .5-11
Stepper Motor Adjustment _....... .............................. ..5-11
Drive Motor Assembly _
5-13
Schematic Diagram. PCB 25227 (4 Sheets) 6-3
Schematic Diagram. PCB 25247 (4 Sheets) 6-11
Schematic Diagram.
PCB 25249 (4 Sheets) 6-19
Logic Equivalent PIN 16271. Location U13 '" _. _............... _ _6-27
Logic Equivalent
PIN 51420. Location U14 _ __ _ 6-29
SA810/860 Diskette Drive. Exploded View (3 Sheets) .. _7-2
Top Plate Assembly. Exploded View. . . . . . . . . . . . _ _ 7-8
Actuator Assembly. Exploded View 7-10
PCBP/N25227 _ _ _ 7-12
PCB P/N 25247 . 7-16
PCBP/N25249............ . _ _..... .7-20
LIST OF TABLES
Table Title
Page
2-1 DC Power Requirements. ...................... . 2-6
3-1
Recommended J1 Connectors _ 3-2
5-1 Maintenance Equipment 5-1
6-1 Schematic Diagram Applicability . . . _6-1
7
-1 Part Number to Figure Reference Cross Reference . . . .. .7-24
7-2 Calculated Failure
Rates. . . 7-27
7-3
Spare Parts Stocking Guide _. . . _ __ 7-27
iv

SECTION I
INTRODUCTION
1.1 GENERAL DESCRIPTION
The compact SA810 single-sided and SA860 double-sided half-height 8-inch floppy disk drives offer areliable, low
cost, high performance solution for OEM
data storage applications which require maximum capacity in the smallest
space possible.
The SA81O/860 drives are less than half the height of the Shugart SA801 and SA851 floppy disk
drives,
fit in comfortably with aCRT, require no ac voltage, and offer up to 1.6 megabytes of unformatted capacity.
The SA81O/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)
I. 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 SA81O/860 provides the best solution to the user looking for acompact, low cost, and reliable 8-inch floppy
disk drive.
The SA81O/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 kbytes
400/800 kbytes
5.2/10.4 kbytes
1-1
SA860
Single/Double Density
0.8/1.6 Mbytes
400/800 kbytes
5.2/10.4 kbytes

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
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
1.2.3 Physical Specifications
SA810
Single/Double Density
250/500 kbytes
250/500 kbytes
3.3/6.66 kbytes
250/500 kbits/sec
83 ms
3ms
13 ms
16 ms
89 ms
165 ms
120 ms
360 ± 2 rpm
3268/6536 bpi
6536 fei
48 tpi
77
1
FM/MFM
SAlOO/102
SA 1011 103
SA120
SA860
Single/Double Density
500/1000 kbytes
250/500 kbytes
3.3/666 kbytes
250/500 kbits/sec
83 ms
3ms
13 ms
16 ms
89 ms
165 ms
120 ms
360± 2rpm
3408/6816 bpi
6816 fei
48 tpi
154
1
FM/MFM
SA150
SA151
SA122
Environmental Limits
Ambient
Temperature:
Relative Humidity:
Maximum Wet Bulb:
DC Voltage Requirements:
Operating
50° to U5°F (9.9° to 46.lOC)
20% to 80%
85 OF (29.4°C)
Storage
-8° to 122°F (-22.2° to 50°C)
1% to 95%
no condensation
Shipping
-40° to 144°F (-40° to 62.2°C)
1% to 95%
no condensation
+ 24.00 ± 2.4 Vdc @ 1.0 Atyp., 1.7 A max., 100 mV ripple.
+5.00 ± 0.25 Vdc @ 0.7 Atyp., 0.7 A max., 50 mV ripple.
NOTE
If the stepper motor is energized by the controller during the single motor start-up time, the drive
will exceed the + 24 Vdc current specification of 1.7 Amax. Under this condition, the current
specification
is 2.2 Amax.
Mechanical Dimensions
Width =
8.55 in. (217 mm)
Height =2.31 in. (59 mm)
Depth =
12.00 in. (305 mm)
Weight =7lbs
(3 kg)
1-2

1 per 109bits read
1 per 10
12
bits read
1 per 106seeks
Mounting
Top loading
Diskette Horizontal Label
Up/Down
Diskette Vertical Label Left/Right
Power Dissipation:
10 watts (34.2
BTU/hr) Standby
28 watts (94.0 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: 5years
Error Rates:
Soft
Read Errors:
Hard Read Errors:
Seek Errors:
Media Life:
Passes per Track: 3.5 x 10
6
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
I. Internal and External Write Current Switching
m.
Power on Reset Circuit
n. Activity LED
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. Acontracting collet/spindle assembly provides precision media positioning and clamping to ensure data inter-
change. Adiskette ejector places the diskette within reach of the operator when the diskette is unclamped.
1-3

1.3.3 Positioning Mechanism
The read/write head assembly is accurately positioned through the use of aprecision HeliCam V-groove lead
screw with aflat nut follower which is attached to the head carriage assembly. Precise track location is accomplished
as the lead screw is rotated in discrete increments by astepping motor.
1.3.4 Read/Write Heads
The proprietary head(s) is asingle 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 acarriage which is located on precision carriage ways. The diskette is held in
aplane perpendicular to the read/write head(s) by aplaten 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 afunction 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 afunctional diagram of the SA81O/860.
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 ahigh 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
[n order for the host sytem 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 adaisy 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.
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 anew 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 may be performed by the drive by jumpering the optional MOTOR OFF delay.
1-4

((
\,
.......
UI
READ D.A.TA
SEP DATA (FM) READ
WRITE
LOGIC
I+- ---
PROTECT
SEP
CLOCK (FM) ASSM
DRIVE SIDE
SELECT SELECT DISKETTE
WRITE DATA
WRITE GATE WRITE
WRITE CURRENT (OPT) LOGIC STEPPER
WRITE PROTECT ACTUATOR
1----1 ~
R/WO
R/W1
R/W HEAD
TRACK SIDE ASSM. -
40
SELECT POWER
ON DRIVE )DOOR
RESET
-\. MOTOR JCLOSED
-SIDE SELECT SWITCH
STEP
DIRECTIONI
"SIDE SELECT (OPT.) INDEXI
DRIVE/"SIDE SELECT (OPT.) SECTOR DETECTOR
MOTOR ON (HEAD LOAD) (OPT.)
IN USE (OPT.)
-~
t
TWO SIDED (OPT.)
--..
CONTROL
TRACK 00
LOGIC
INDEX
IN USE
SECTOR LED
READYITRUE READY (OPT.) TRACK
TRUE READY (OPT.)
00
DISK CHANGE (OPT.) SENSOR
ALTERNATE 1/0 (2 lines)
DOOR
LOCK
-..
'SA860 ONLY
SOLENOID
FIGURE 1-2. SA810/860 FUNCTIONAL DIAGRAM 39216·02-A

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 ps, will be stored in abuffer 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 aplus logic level (2.5 Vto 5.25 V), apulse on the STEP line will cause the
read/write heads 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 aminus logic level (0 Vto 0.4 V), apulse 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
DRIVE SELECT
DIRECTION SELECT
.;.... ....,
liN ~
4L-._-
1
!'S-M-IN -~~-!
OUT
-1I'sMIN
STEP
"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
FIGURE 1·3. TRACK ACCESS TIMING, STANDARD SEEK
1-6

l-- 15 I'S MIN"
I2.9 ms MAX"
55
LSU 5
I- 151's MIN" ,~I
-2.9 ms MAX
-
11's MIN--
STEP
_.......JI
I
'r--- -SS-, r- - - -
I1 I I
'-- ---1. - --S~ ... 1 ----1. _
DIRECTION SELECT ....:....____ .!c OUT
I 'r-- ---"U ':
~
~I :,,'MI:------\~~-1I'SMINL-----
90 ms
MIN --
DRIVE SELECT
DC POWER
'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.
39216-31
, '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 a3 ms pulse rate. Pulses received at greater than a3 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.
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. Aplus logic level on the SIDE
SELECT line selects
the read/write head on the side asurface of the diskette. Aminus logic level selects the side 1
read/write head. When switching from one side to the other, a100 JlS delay is required after SIDE SELECT
changes state before aread or write operation can be initiated. Figure 1-5 shows the use of SIDE SELECTprior to a
read operation.
DC POWER
DRIVE SELECT
STEP
SIDE
SELECT
(SA860 ONLY)
I!-----------J5 \r-
5
--
\.90 ms MIN:U 55
I I I-.J I-1001'S
1-~------\5~~~---
WRITE GATE
VALIu READ DATA -------~----......,
l-:f,~'~
-165 ms MIW_!
• Or when TRUE READY comes active.
_1_
50
l's
MIN
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 DR[VE
SELECT line.
b. Selecting
head (SA860 only).
c. WR[TE
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.
2.00 /,s 2.00 /,s
NOM NOM
4.00/,s
NOM
A
I
1 I
B A B A
W'Illl
'
----.j I.--- 200 ±50 ns
______ 1 ,.... ~
~ UUU
------..1 I.-- 200 ±50 ns
SEP CLOCK
SEP DATA
READ DATA
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. 39216·05
FIGURE 1-6. READ SIGNAL TIMING (FM ENCODING)
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 aclock bit at the start of every bit cell. MFM encoding rules allow 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.
[n 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).
[n the standard SA81O/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. [n systems
using
MFM encoding, data separation is performed outside the drive. [n 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 the SA81O/860 OEM Manual (P /N
39216-2) .
1-8

0
BIT
CELLS0000
FM I
r-
-I
2F
I
I
I
I
I
I
I00000
MFM 1
o ]l- __ 0_....l.... __ 0 _...l- __ --'
o
FIGURE 1-7. FM AND MFM CODE COMPARISONS
1.4.9 Write Operation
Writing data to the SA81O/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 awrite 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.
STEP
DC POWER
WRITE DATA
DRIVE
SELECT
---l
r--,;m'"'N --I
r165m5MIN1
-I-U~----
f- 9~~5~-l -II r100 , ,5 MIN
SIDE SELECT
-, I
(SAS60 ONLY)
16 m5 MIN" 1---
1
WRITE GATE -------------.1 __
1_
-1 I- 4 ,,5 MIN
------L.JLJ"LJ
*0 r when TRUE READY comes active
39216·07·A
FIGURE 1·8. WRITE INITIATE TIMING
1-9

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 stream depends
on the pattern it forms with nearby bits.
For more details regarding data encoding and formatting for SA810/860 drives, refer to the OEM manual (PIN
39216) .
1.4.10 Sequence Of Events
The timing diagram shown in figure 1-9 illustates the necessary sequence of events with associated timing restric-
tions for proper operation.
VALID CONTROL
AND OUTPUT SIGNALS
SS
'j~
',--'
II
~
I-I
SS
f--"90 ms MIN
~500mSMAX
. ~ --1
I I
___ ~I __ ...L' __ ""- --l.
1_ 100/,S---j
r-- MAX I
90 I
ms
MIN
-----
lI
II
I
II
j -n 'r--l
I I I I
'l~msJ ~ I --...II----\S~S----------
I ~~(~ I~I ~ HMIN~ ~I(~ ::1l.-l/(Sr-M_IN ---Il~'rS----------
90 m~ IIn1 "s I lnJ '
MIN 1-+ -.j~ ---jNOTE2t-
16ms
NOTE 2..J 1~_16 mS-l ~
~ MIN Ir----:---I
II
~6 ms I 'fJ I I~ ~S'SI------
I'~IN - ~16 ms
III
SS _I MIN I
I.. 100 "s MIN ----l_~.
I ---,_....IS\\o-S _
I.. II NOTE 1 =:J l~4M~ ~NI I
SS UU U Ur------
-J I-l~I~S -I r-50 I'S MIN
-~~-NO-TE 1=lJ1f1rU S~
WRITE GATE
TRUE READY
DIRECTION
SELECT
STEP
WRITE DATA
VALID READ
DATA SIGNAL
SIDE SELECT
(SA860 ON L Y)
DC POWER
DRIVE SELECr
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/,s to 2.9 ms between pulses .
39216·08·A
• 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.
FIGURE 1·9. SA81 0/860 GENERAL CONTROL AND DATA TIMING REQUIREMENTS
1-10

SECTION II
ELECTRICAL INTERFACE
2.1 INTRODUCTION
The interface of the SA81O/860 Diskette Drive can be divided into two categories:
a. Signal Interface
b.
Power Interface
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 Lines
b. Data Transfer Lines
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 P1/J1.
2.2.1 Input Lines
There are twelve signal input lines. Nine are standard and three are user installable options.
The input signals are of three types, those intended to be multiplexed in amultiple 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.)
b.
IN USE
c. EXTERNAL WRITE CURRENT SWITCH
2-1

HOST
MAX FEET
10 FT FLAT RIBBON OR
20 FT TWISTED PAIR SA810/860
Jl
EXTERNAL WRITE CURRENT SWITCHING"
21
TRUE
READY"
87
TWO
SIDED' +
10
9
DISK
CHANGE'
12
11
SIDE SELECT' +
14 13
IN USE'
16
MOTOR ON' (HEAD LOAD) 15
18
INDEX
17
20
19
READY
22
21
SECTOR 24
2:1
DRIVE SELECT 1(SIDE SELECT OPT) +26 25
DRIVE SELECT 2(SIDE SELECT OPT) +
28
DRIVE SELECT 3(SIDE SELECT OPT) +
27
30
DRIVE SELECT 4(SIDE SELECT OPT) +29
32
DIRECTION SELECT (SIDE SELECT OPT) +
31
34
33
STEP 36 35
WRITE
DATA
38
WRITE GATE 37
40 39
TRACK 00
42
41
WRITE PROTECT
44
4
READ DATA
46
SEP DATA
45
48
SEP CLOCK
47
50 49
-
+5 VDC
I +5 VRETURN 3J2
<I
~
+24 VDC 1
r+ 24 VRETURN 2
-:"-
-
5
DC
-"- J7,'T!
rrJ-n
GND -=- FRAME GND
TWISTED PAIR 39216-09
'JUMPER ENABLED ALTERNATE I/O LINES.
+SA860
ONLY
FIGURE 2·1. SA810/860 INTERFACE CONNECTIONS
2-2