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Application Manual 


Flexible Disk Storage Drive 
3.5 INCH 

(25.4 mm Height) 

(DC 5V only) 


JU-257Axx6P 


(MLC 6 of JU-257A Series) 


e * bé 33 
Revision L 


Panasonic 


JU-257AXX6P(L) REVISION CONTROL SHEET 


05680A4 May. 12 ‘97 1st Edition 


SECTION 


SECTION Il 


\ 


CONTENTS 


Page 
INTRODUCTIONS wricsecteccsics Ss cisevek cnaishen eddavietc acd pies Sect cat svcaadedinacdadeoidistihndedieaspateke cat Sietane 1-4 
1:4, (GENERAL /DESGRIP TION sxcscsccasiciciseisdeccetes thee dendaiiadtces cas vente teevauaite oats ietede cod ogeatoeess 1-1 
1.2 SPECIFICATIONS SUMMARY ............:cccssccccssscesessssssscssssesssrscasececsucussessessussueeesssseness 1-1. 
1.2.1 Performance Specifications ......... cc ceeseccssssscessceessseesssenaceseesaesatesssnaesessssaes 1-4 
1.2.2 Functional Specifications 2.0... eccesscessssssneessenseerssssstsesseeesstesesseraseseesees 41-2 
4.2.3 ‘Reliability Specifications isis: icisseess caste iuns isvorensaisenvesssviancedsooezeretaastiabidlanvereleds 1-2 
1.2.4 Physical Specifications 0... ecceeseesceessesecteseeeensersnsesseessnessnaesaeesseesenes 1-2 
1.2.5 Power Requirement... ccececseessessscsssecssccscseecsneesssensseeseetsasevsnasteeseesessee? 1-3 
1.2.6 Diskette REQUIFeEMENtS 0.0... esl cetecseceseceseteceseessscestenssersaeesseerssassassseeessets 1-4 
43> - CHARACTERISTICS wii iciiscauswctetesieetas case. edu deddecanentin sud stiedia dedasvddaeeseeuscans wees eubvavec Slates 1-5 
13:4. . “Hire Margin. CEM) ssccscetesccas tees Sis cexsetesn oes inighciss saga td aartacienesdesteeas dei taetaseatiaceeee 1-5 
1.3.2 Positioning ACCUrACY 0. eeecereeeteeesessacceessaresceesesseessoneteesssoesusesseeseenees 1-5 
1.3.3 Positional Relation between Index and H@ad............cccsscssssscesssscesscesreesseentes 1-5 
73:4. (PreCOMPENSALION sissies peteateevessnyiiete tieeeeaeee Gas aut deters tencieciese on 4-5 
44 INTEREAGE SIGNAL. caico.corseecetarasdeaesdns cocacctehoncens colewcteaccsidua cdaedasectaseddusaeavanstecvors sees 1-6 
RAD SIGMA CVS cass ccs esestesetuln eosteusui sec essen uadeans tas elsagaacdponen saneeauasteriadst Aumedtinsentes 1-6 
1.5 FUNCTIONAL CONSTRUCTION .......cccccsscsscersrcecssssecsesesseessseceetsessseessescesteasaceusceseneees 1-6 
1.5.1 Read/Write and Control Electronics.........c...cccccccccsesscssesesssecesssscesssseasersesenes 1-7 
1.5.2 Drive Mechanism........... aes talag lhe Sc huest Sx a bona epee utinaaxmcniasceioommuiaes 1-7 
1.5.3 Precise Track Positioning MECHANISM ...........ccccccceccsecescesssssssssssesessensneeseereeees 1-7 
15.4 ‘Redd / Write heads. i.ic.c.cvssticeceescveessotetssdeaigucdesds cssadvnelssnivedendess iiesondecavedaceeleees 1-7 
45:5 ~. TRECOMGING: FOPMats iss: tisdessc cock teh ceceosueres ovideces ceadeden Mad acSag ale leas dhe beaten cecdvueti ves 1-7 
4.6. (GENERAL DESCRIPTION ise. ctceeceeecescncsaiuenidetea eeu Se saseodedovseccyehesstesta Audselideciocte sietddee 1-7 
ELECTRICAL INTERFACE AND TIMING SPECIFICATIONS 0... ceccescccssseessseeteesesseeees 2-1 
24 INFRODUGTION Ss sesceiscscsGeveaes acest seuaede pa cdbs auseeanaseu de avaticeeaa sh scdees eet tedcesbeh as sauna dasa aeeee 2-1 
20° SIGNAL ANTERFAG Eis ciccazccssdasigerss vs chGsevesdeareheeiiens ts pions tuatieaid dives stele avdaeuaemnreeaseesss 2-1 
23. WADUt- LINSS acs ecascce cise cih ine de due cvebatan beste eaese ses sand banees sub SoulubstesvensasdyledsbeasBertcpacberedieasdeaesves 2-3 
2.3.14  Inptt Line Termination isi: ccsc.ccscescesseeedcesties dea teusecics aoagebaased Fecstavideceulavegsbsetates 2-3 
23-22 -— Drive Selects Acca cienctett Aon Ae ee ee ee eth ved easels 2-3 
PSB = MOtOr OAs hedivedereecdcsseaateadeass uals warssoen bctuandis Soaietloe sais beeosnceintestathetachs thesia 2-3 
23:4. - Direction Select... ..c adsense eens ein lc homaeles 2-3 
B35). “Ste pun ievivisdervsieesss aha ntee el oma eae DANS As Me acter seet es 2-4 
D236: --= Side A:Selectaseinietadie chit ieee ae ean aie ee aaa 2-5 
DEG 7 WN Te GALS Seeds 2A ss Son doae oda da os obese dhancuseaa ade s5 Sk esa GPAs NoeGed ace edeseTivun plete Rev anete 2-5 
2.3.0. --— Write: Datawssns esncidth elated, hie, Baie Reels aa 2-5 
DAS ~ QUOT BIE S iis eats cottict tase sabiasaaecscii vanadua adieuaeat tng tadandens ie saenctdsdenlaoaiae uslieateoluneaiedanan 2-7 
BAY = INdeX ecnitiacs nth eine arian fis Ai eid U eee 2-7 
DA: =SRead Data ve 25 deceive Auto ia ma eee et ak ae ee 2-7 
DAB». SWite Protects, j.sc.cel eck settotsec encpcibee Lote rdedis tee cce  laddaisiativminn deadeedd adaacee tele veces 2-8 
DAB) STACK: OO sere car cukcte trees asche eteed ei aust co cheats oeces Cowes hea Sete dae ea 2-9 
245. TS DISK: CHANGC si sisesoesees decd est eens cgsdote tees ae N cecwesccgedeaets debeadedeaareses evs casdbmenen ede deee 2-9 
2:5.) POWER: INTERFAGE ssiciciccccstiseectereieipads sadeve sateveclonsuaaisredes aes aus aeaawe anes 2-10 
2.5.14 POWER SEQUENCING ui cccccsseccscsssscesscecssssecceseeesessseesetsseseuscsenees 2-10 
2.6 FRAME GROUND AND SIGNAL GROUND... cccssesccsestnesssesesceessesasenatesaeeeeees 2-10 
27 SEQUENCE OF EVENTS ox casei caxcaudtnetalittnesene atin aid asad antici einen: 2-11 


SECTION III 


SECTION IV 


SECTION V 


SECTION VI 


SECTION VII 


ELECTRICAL CONNEC TIONS cosssicsdasiete cy shs cid oe susictnei vous dub cinosnsucuseslastiedbaylads. spot gqoesenidesaaleans 3-1 
BA ANTARODUGT ION. ices scushecdisininansuts sietuaridadetanbabeinies satdaanceeuseaaianteginuanaeoatemaieebtdeesees bara 3-4 
3.2. J1/P1 CONNECTOR (I/F CONNECTOR) wiscesscce.sensovenecsuansossentdidcvenetestediehtesaaceraserdent 3-1 
3.3 J2/P2 CONNECTOR (POWER CONNECTOR) ........ccccssscessesssscctscsssseeassseesesseeerseas 3-2 
DRIVE MOUNTING AND DIMENSION uu... cc ecececesseceecsccsecsneeesessessecssseseessecneesnesessensvese 4-1 
44 GENERAL cui uyeccecensteeenagicrnder betorionteun ations atadaa dedi aieth Renaacaisin haveiebe i Suinensmurends 4-1 
Bie MOUNTIN Gia sasciai eis cous eadins versinadig aie iiahaceiln sv anmdanpotaatuede a deatlann la hiattanchaceamteonnanstvart 4-4 
4:3° MECHANICAL DIMENSION inccssvessccscassscvassteaccredbubeawennctnenserabocguisdlnadencenenasusiuncnwesyeavioes 4-2 
ERROR RECOV EG coors ssussoisauiiceaacimilichimaneas- tense cdediandihlitelcnaniecnnaealviguyiheavcSuendisabexsiessnnaunctees! 5-1 
551. oWRITE-ERROR aissecsestli esse tureett aii seterteutatescentsbvaiciscatis dates teasseatveaateess sees deer adeodieats 5-1 
BD ABAD ERROR satuiisocasatuncinmtaun siutines an ctl stnteiny stucecoieorsuesuagtamekensoe spainaeuasaneios babaielvaneyty 5-1 
5S SEEK ERROR siasyicostisieveneZeacunan’ sunaclee canvass Gvassgesaliateatanncddedh eeoaluabeeevedypacniediveancaneaaaeatiy 5-1 
RECORDING FORMAT cicsrocedi veiled cnssttec Gecereasie. sSvaauaescstaess deavelinderiacsstere ceddhavenzenee deh laglseateeds 6-4 
6.1. “GENERAL jira sdusrectic saectttins ata teiaaneaiise pene pectriaetnapiclesvis dsseastieatieuatias ae 6-1 
6.2 JU-257A6P SOFT SECTORS RECORDING FORMAT uu... ceeseeesessstseesessseeeseseeeees 6-2 
OPERATION PROCEDURES wishcsnivivitsscctatavfesraetssanya aeqealsscatsnusdcbusesiteat pnt ted dctapaacrasith wreddoes 7-1 
TA INTRODUCTION fis tvcetes rere acatpiartasaceccteas rent com viesesdeegevesaslgauees avesusel vevinntd onaddvbea deeebnrseds 7-1 
7.2: ‘DISKETTE: LOADING ciate hich deli dant tevin ld tis dnc aeie: 7-4 
Fo, DISKETTES HANDEL IING ce vssctse tan ctu tpieit adeiteeadees dharrcaw sade vdiauceedeqaeat ndat ouatisabarsesbainagiabandnges 7-1 
74: WRITE;PROTEGTUREATURE iicczit.ca. ss docntess caeeereecGitdints Lesenstrcevveadede be theseaneseveedigneeuss 7-2 


1.1 


1.2 
1.2.1 


SECTION | 
INTRODUCTION 


GENERAL DESCRIPTION 


Model JU-257A6P is 3.5 inch double - sided flexible disk storage drive, provided for MLC-6 of 
JU-257A series. 

JU-257A6P offers same features as JU-257 series; 2.0 Mbytes unformatted storage capacity, 3 ms 
track-to-track accessing, 300 rpm of rotational speed, only +5V dc power for operation, and 
backwards capability to read/write the diskette written on a standard 1.0 Mbyte diskette. 


When the JU-257A6P is using a normal density diskette (2DD), it works as a standard 1.0 Mbyte drive. 
With a high density diskette (2HD), the JU-257A6P becomes a 2.0 Mbyte drive. 


In addition, the JU-257A6P provides precise access mechanism, high performance 1 - chip LSI, TTL 
interface, compact direct drive spindle motor, and lower heat dissipation along with improved 
reliability. 


Key Features : 
Physical size : 101.6X 150 25.4 mm (WXDXH) 


Weight : 390 g 


OOOOOOOYS 


Single - sided PCB 
SPECIFICATIONS SUMMARY 


Performance Specifications 


Precise screw / follower actuator. 

1 - chip (control logic and R/W) LSI. 
Compact DD spindle motor. . 

Lower power consumption and TTL interface. 
3.5 inch FDD standard interface connector. (34 pins) 


High Density Mode 


Normal Density Mode 


Capacity (in bytes) 
Unformatted (MFM) 
Per Disk 2,000,000 1,000,000 
Per Surface 1,000,000 500,000 
Per Track 12,500 6,250 
Formatted (MFM) 18 sectors / track 9 sectors / track 
Per Disk 1,474,560 737,280 
Per Surface 737,280 368,640 
Per Track 9,216 4,608 
Per Sector 512 512 
Transfer Rate (MFM) 500 kbits/s 250 kbits/s 
Access Time 
Track to Track 3 ms 3 ms 
Settling Time 15 ms 15 ms 
Average 79 ms 79 ms 
Latency (avg.) 100 ms 100 ms 
Turn Around Delay (min.) 18 ms 18 ms 


1-41 


1.2.2 Functional Specifications 


High Density Normal Density 
Motor Start Time (max.) 500 ms 500 ms 
Rotational Speed 300 rpm 300 rpm 
Recording Density (MFM) 
(inner most track) 17, 434 bpi 8,717 bpi 
Track Density 435.467 tpi 135.467 tpi 
Cylinders 80 80 
Tracks 160 160 
Read / Write Heads 2 2 
1.2.3 Reliability Specifications 
MTBF 30, 000 POH under typical usage 
MTTR 30 minutes 
Component Life 15, 000 POH or 5 years 
Error Rates 
Soft Read Errors 1 per 10° bits read 
Hard Read Errors 1 per 10’? bits read 
Seek Errors 1 per 10° seeks 
Durability 
Diskette Insertion / Ejection 30, 000 times 
Seek 10X10’ seeks 
Media Wear 3.5 10° passes 
1.2.4 Physical Specifications 
Operating Non - Operating 
Environmental Limits 
Ambient Temperature 5 to 45°C ~ 40 to 60°C 
(41 to 113°F) (—40 to 140°F) 
Maximum Temperature Gradient 20°C (36°F) /H 20°C (36°F) /H 
Relative Humidity (non-condensing) 20 to 80 % RH 5 to 90% RH 
Maximum Wet Bulb Temperature 29°C (84.2°F) 29°C (84.2°F) 
Vibration (except resonant point) 5.88m/s7(0.6G) 19.6m/s*(2G) 
5 to 500 Hz 10 to 500 Hz 
Shock (half sine wave) 49m/s?*(5G) / 11ms 588m/s*(60G) / 11ms 


DC Power Requirements : +5V+10%, 0.29A (typ)/0.71A (max)/0.9A (peak), 100mvV p-p ripple 
Power Dissipation : 1.5 W under continuous typical, 20 mW under standby* 
* standby : Drive select off, drive motor off, and step motor off. 


Mechanical Dimension 


Width 101.6 mm 
Height. 25.4 mm 
Depth 150 mm Including front bezel 
Weight ; 390g 
Mounting Inclination Limits 0 to 20 deg mounted vertical / horizontal 
Diskette Operating Force 800 g for inserting, 1,500 g for ejecting 
Acoustic Noise 45 dBA- fast at 1 meter from drive at 3ms seeking 


1-2 


1.2.5 Power Requirements 


a 5V — ee oe 10% Max Alo ple 100 mVp-p 


. S5A Ne 
Current When operating o. 29h 
Write 0.35A imax 
0.29A 
At motor start Pe we ne) 
Power 


requirement 3.9W (max) 


Power consumption 


1 "OW imax) 


2BmW | (max) 
Stand by 20mW {typ 
Note: "Stand by mode” states all input signals “off”. 
Note : At motor start: Up to 250 ms after motor start 


1 
2. Seek: For seeking after 250 ms subsequent to motor start 
3. 


Power requirements represent the values in the case when a diskette with a load of 
35 g - cm is used. 


4. Peak current values are specified in figure 1 - 1. 
5. Max/ Typ: When +5V +10% / +0% at DC power connector J2. 


TYPICAL 


CURRENT 
{A) 
0.81 A typ 0.81 A typ 
0.8 
0.64 A typ 2ms typ 6ms max 
0.6 
0.4 
0.2 
0 Bae ae 
Stand by Motor on Read Seek Write Read 
FIGURE 1-1 DC POWER PROFILE 
Note : High power consumption is required against the motor-start after start-up of Spindle motor 


during the 250 ms. 

‘When “Step Mode” has been used during the 250 ms from motor-start, the power 
consumption will rise to a peak which will cause the DC power supply heavy. 
To prevent the load, it is recommended not to use the Step Mode during 250 ms after the 
motor-start. It is required to use the motor-start after 18 ms from STEP signal. 


1.2.6 Diskette Requirements 


Use recommended diskette. (High density For 2.0MB Recording) 
(Normal density For 1.0MB Recording) 


1-4 


1.3 


1.3.4 


1.3.2 


1.3.3 


1.3.4 


CHARACTERISTICS 
Time Margin (TM) 


In the case of FM, a random pattern or a repetitive pattern of 11100101 = (E5). 
In the case of MFM, a random pattern or a repetitive pattern of 1011011011011011 = (B6DB). 


The time margin on reading or writing of the above pattern satisfies the following specification values. 


Self read / write : TM & 0.15t 

Compatible read / write : TM 2 0.10T 
t is the clock-to-clock interval, 8s for FM and 44s for MFM at 1.0M Mode, 
44s for FM and 24s for MFM at 2.0M Mode. 


Positioning Accuracy 


RN = 39.5 -0.1875N +£0.025 (mm) (side 0) 
RN = 38.0 -0.1875N +0.025 (mm) (side 1) 


Where RNedistance from spindle center to the track, and 
Measuring conditions : N=40, 2342°C, 50410%RH 


Positional Relation between Index and Head 


The time - base error of the positional relation between read / write head and index signal detector is 


not greater than 1600 us between drives. 


Precompensation 


The recommended write data Precompensation values are 100~150 ns (2.0M - MODE) and 100~ 


250 ns (1.0M - MODE), for all tracks. 


1.4 INTERFACE SIGNAL 


1.4.1 Signal Level 
Signals exchanged between the controller and drive are all at TTL levels (low true). 


input impedance : 1k Q Output sink current : 48mA 


1.5 FUNCTIONAL CONSTRUCTION 


The JU-257A6P drives consist of : 


a. Read/Write and Control Electronics 
b. Drive Mechanism 
c. Precision Track Positioning Mechanism 
d. Read/Write Heads 
— READ DATA WRITE 
PROTECT 
—WRITE DATA SENSOR 


STEPPER 
ACTUATOR OR CONTROL 
—SIDE 1 SELECT ME EC TaONIeS 
R/W HEAD 
ASSY 
— DISK CHANGE STEPPER DIRECT 
—WRITE GATE DRIVER DRIVE 


MOTOR 


—STEP 
— DIRECTION 


— DRIVE SELECT 
—MOTOR ON 
CONTROL DETECTOR 
LOGIC 
—WRITE PROTECT 


— TRACK 00 IN USE 

— INDEX | sak 
HIGH DENSITY 
MEDIA SENSOR 


DISKETTE LOADING _ 
SENSOR MECHANISM 


FIGURE 1-2 JU-257A6P BLOCK DIAGRAM 


1.5.1 


1.5.2 


1.5.3 


1.5.4 


1.5.5 


1.6 


Read/Write and Control! Electronics 
The main PCB contains the following : 


Head Positioning Actuator Driver 

Read/Write Amplifier and Transition Detector 
Drive Select Circuit 

Control Logic Circuit 

Side Select Circuit 


oao7p 


and the Spindle Motor PCB contains the following : 


f. Index Detector Circuit 
g. Write Protect Circuit 
h. Spindle Motor Drive and Control Circuits 


The Head Positioning Actuator moves the read/write heads to the desired track on the disk. The disk 
is loaded on to the read/write heads by an elevator mechanism when the diskette is inserted. 


Drive Mechanism 


The DC drive motor under servo speed control (using an integral tachometer) rotates the spindle at 
300 rpm through a direct-drive system. A magnetic chucking device in conjunction with a metallic hub 


on the diskette provides precise diskette positioning to ensure data interchange. The motor control 
electronics are contained as part of the spindle motor assembly. 


Precise Track Positioning Mechanism 


The read/write head assembly is accurately positioned through the use of a lead screw which is 


attached to the head carriage assembly. Precise track location is accomplished by a precise stepping 
motor. 


Read/Write heads 


The specially-bonded ceramic and ferrite read/write heads contain erase elements to provide erased 
areas between data tracks. Thus, normal interchange tolerances between diskette and drives will not 
degrade the signal-to-noise ratio and diskette interchangeability is ensured. 


The read/write heads are mounted on a carriage which is located on a precise carriage assembly. 
The diskette is held in a plane perpendicular to the read/write heads by pins located on the base 
casting. This precise registration assures perfect compliance with the read/write heads. The 
read/write heads are in direct contact with the disk. The head surfaces have been designed to obtain 


maximum signal transfer to and from the magnetic surface of the disk with minimum head/diskette 
wear. 


Recording Formats 


The format of the data recorded on the disk 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 any one track. 

For detailed discussion of the various recording formats, refer to Section VI. 

GENERAL DESCRIPTION 


The JU-257A6P has been listed with Underwriters Laboratories, Inc., and the Canadian Standards 
Association. 


1-7 


SECTION Il 
ELECTRICAL INTERFACE AND TIMING SPECIFICATIONS 


2.1 INTRODUCTION 


The interface of the JU - 257A6P can be divided into two categories: 


a. Signal Interface b. Power Interface 
The following provides 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. Contro! Lines b. Data Transfer Lines 


All lines in the signal interface are digital in nature and provide signals to the drive (input) or to the host 
(output) via interface connector P1/J1. 


HOST SYSTEM JU-257A6P 


—DRIVE SELECT 4 
NC 


TTT SSIEn RE 


—~ MOTOR ON 
— DIRECTION SELECT 
—STEP 


——S—— 


—WRITE DATA 


—WRITE GATE 


— TRACK 00 
—WRITE PROTECT 
— READ DATA 
—SIDE SELECT 

— DISK CHANGE 


= Vdd 
AC LOGIC 
GND GND 


Note J1/pin3, J2/pin4 : NC 
FIGURE 2-1 INTERFACE CONNECTION 


1) Receiving 


DRIVE DRIVE 
NO. 0 NO. 1 


+ MAX3 FEET > 
(1 METER) 
RIBBON OR 
TWISTED PAIR 


74HCT14 
Equivalent 


7438 
Equivalent 


Note 1 : Besure to change the terminal resistance as follows when many units are 
connected. 
Two units : 5002 


Note 2 : The level of the signal line is not assured if power of any drive has been 
switched off. 


2) Transmitting 


+ MAX3 FEET > 
(1 METER) 
RIBBON OR 

TWISTED PAIR 


SN7438 
Equivalent 


SN74LS14 
Equivalent 


FIGURE 2-2. INTERFACE SIGNAL DRIVER / RECEIVER 


2-2 


2.3 


2.3.1 


2.3.2 | 


2.3.3 


2.3.4 


Input Lines 


The input lines have the following electrical specifications. See figure 2-2 for the recommended 
circuit. 

True = Logical zero = Vin +0.0 to 0.8V @ lin = 6 mA (max.) 

False = Logical one = Vin +2.2 to +5.25V @ lin = 250A (open) 

Input impedance = 1 k2 


Input Line Termination 


The JU-257A6P has been provided with the capability of terminating the eight input lines listed below. 


a. — DRIVE SELECT 1 e. —SIDE 1 SELECT 
b. - MOTOR ON f. —WRITE GATE 
c. -DIRECTION SELECT = g. ~WRITE DATA 
d. —STEP 


These lines are terminated through a 1kQ resistor which is built - in the 1 chip LSI. 


In a single drive system, this resistor provides 1kQ input impedance for input lines. In a multiple 
(two) drive system, the input impedance is varied to 5002. 


— Drive Select 1 


Logical zero on the interface selects a desired drive to enable all other signal lines (except 
— MOTOR ON). 


The ACTIVITY LED on the selected drive will turn on when the corresponding DRIVE SELECT signal 
is active. 


— DRIVE SELECT 1 
Ty —-+| e— | be Te 
OFF 


— ACTIVITY LED ON OFF 


Th, T280.5 ms 

FIGURE 2-3. IN USE TIMING 
~— Motor ON 
This input, when activated to a logical zero level, will turn on the drive motor allowing reading or writing 
on the drive. 500 ms delay after activating this line must be allowed before reading or writing. 
All motors in a daisy chain configuration are activated by —MOTOR ON. 
— Direction Select 
This interface line defines the direction of motion the read/write heads will take when the —STEP line 
is pulsed. An open circuit, or logical one, defines the direction as “out”. If a pulse is applied to the 
— STEP line, the read/write heads will move away from the center of the disk. Conversely, if this input 


is shorted to ground or a logical zero level, the direction of motion is defined as “in”. If a pulse is 
applied to the — STEP line, the read/write heads will move towards the center of the disk. 


2-3 


2.3.5 


—Step 


This interface line is a control signal which causes the read/write heads to move in the direction of 
motion defined by the —DIRECTION SELECT line. This signal must be a logical zero-going pulse 
with a minimum pulse width of 14s. Each subsequent pulse must be delayed by 3 ms (minimum) 
from the preceding pulse for normal mode. 

The access motion is initiated on each logical zero to logical one transition, or at the trailing edge of 
the signal pulse. Any change in the —DIRECTION SELECT line must be made at least 1 us before, 
and must be maintained 1s after the trailing edge of the step pulse. 

Seeking the read/write heads from one track to another is accomplished by: 


Activating the —DRIVE SELECT 1 line 

Selecting the desired direction using the —DIRECTION SELECT line 
—WRITE GATE being inactive 

Pulsing the -STEP line 


ae op 


Multiple track accessing is accomplished by repeated pulsing of the —STEP line until the desired 
track has been reached. As mentioned above, with the —DIRECTION SELECT line at a plus logic 
level (2.2 to 5.25V), a pulse on the —STEP line will cause the read/write heads to move one track 
away for the center of the disk. With the —DIRECTION SELECT line at a minus logic level (0 to 0.8V), 
a pulse on the —STEP line will cause the read/write heads to move on track closer to the center of 
the disk. The pulses applied to the —STEP line must have the timing characteristics shown in Figure 
2-4, 2-5. 


- DRIVE SELECT es ee 


OUTER 
— DIRECTION 
SELECT 
15 min 
1uzsmin . 
—> 14s min 
—STEP 


ts min | 
3ms min 


FIGURE 2-4 TRACK ACCESS TIMING 


1“s min 


2-4 


— DIRECTION 


SELECT | 
| ¢ ; | 1.04s min 


| 3.0 ms min | 
— STEP at | ie © i at 
| 1.0“s min 


f 18ms min 
Ous min 
DRIVE | disable | 
CONDITION Eaanle 
FIGURE 2-5 NORMAL STEP MODE 
Note : After seeking, 18 ms (minimum) delay from the trailing edge of the last step pulse is required 


before any read or write operation can be initiated. 

Also, 18 ms (minimum) delay is required before seeking again, after seeking is accomplished, 
after detecting —TRACK 00 signal, or after changing the direction with —DIRECTION SELECT 
signal. 


2.3.6 —Side 1 Select 


This interface line defines which side of a two-sided disk is used for reading or writing. An open circuit, 
or logical one, selects the read/write heads on the side 0 surface of the disk. A short to ground, or a 
logical zero, selects the read/write on the side 1 surface of the disk. When switching from one head to 
the other, a 100s delay at 2.0M mode or a 200us delay at 1.0M mode is required before any read 
or write operation can be initiated. 


2.3.7. —~Write Gate 


The active state of this signal or logical zero, enables write data to be written on the disk. The inactive 
state or logical one, enables the read data logic and stepper logic. 


2.3.8 —Write Data 


This interface line provides the data to be written on the disk. Each transition from a logical one level 
to a logical zero level will cause the current through the read/write head to be reversed, thereby writing 
a data bit. This line is enabled by - WRITE GATE being active. 

—WRITE DATA must be inactive during a read operation. 


Writing data to the JU-257A6P is accomplished by: 


a. Activating the —DRIVE SELECT line 

b. Activating the —MOTOR ON line 

c. Activating the —WRITE GATE line 

d. ‘Pulsing the —WRITE DATA line with the data to be written 


The timing relationships required to initiate a write data sequence are shown in Figure 2-6. These 
timing specifications are required in order to guarantee that the position of the read/write heads has 
stabilized prior to writing. The timing specifications for the write data pulses are shown in Figure 2-7. 
The clock-to-clock interval (t ) is 82s for FM and 4s for MFM at 1.0M mode, 4us for FM and 2us 
for MFM at 2.0M mode. 


2-5 


—MOTOR ON | 7 . 


— DRIVE 


SELECT 1 
750s min 
~WRITE GATE | , | | 
2.0M-MODE 4.0 “4s max 2.0M-MODE 4.0“s max 


1.0M-MODE 804s max" | | 1.0M-MODE 8.04s max 
—WRITE DATA | | | | | | 


FIGURE 2-6 WRITE INITIATE TIMING 


—WRITE DATA 
Cc D C C D C 
: 150 ns min t £20ns t/2 +20ns 


1000 ns max 


tus min 


~ STEP 


18 ms min 


FIGURE 2-7. WRITE DATA TIMING 


Write data encoding can be FM or MFM. The recommended write data precompensation values are 
100~150n (2.0MB-MODE) and 100~250ns (1.0M-MODE), at all tracks. The direction of 
compensation required for any given bit in the data stream depends on the pattern it forms with 
nearby bits. 


Note : When this signal is activated, 18 ms (minimum) delay is required after the trailing edge of 
the preceding —STEP pulse, and 100s (minimum) delay also is required from the 
changed —SIDE 1 SELECT signal. 

After this signal is inactive, 750 4s (minimum) delay is required ; 
a) to turn off the drive motor 
‘b) to deactivate the —DRIVE SELECT 1 signal 
c) to move the read/write heads with causing the —STEP signal 
d) to change the level of the —SIDE 1 SELECT signal 


2.4 


2.4.1 


2.4.2 


Output Lines 


The output control lines have the following electrical specifications. See figure 2-2 for the 
recommended circuit. 


True = Logical zero = Vout +0.0 to +0.4V @ lout = 48 mA (max.) 
False = Logical one = Vout +2.4 to +5.25V (open collector) @ lout = 250 “A (max.) 


—Index 
This interface signal is provided by the drive each motor revolution. 


There is one pulse on this interface signal per revolution of the disk (200 ms). This pulse indicates the 
actual start of a track. 


When using the —INDEX signal, look for an edge or transition rather than a level for determining the 
status. 


— INDEX | | | | 


0.8 to 8ms les 


FIGURE 2-8 INDEX TIMING 


200 + 2ms 


— Read Data 


This interface line provides the “raw data” (clock and data together) as detected by the drive 
electronics. Normally, this signal is a logical one level and becomes a logical zero level for the active 
state. 


Reading data from the JU - 257A6P is accomplished by: 
a. Activating —DRIVE SELECT line 
b. Activating ~MOTOR ON line 
c. WRITE GATE being inactive 


The timing relationships required to initiate a read sequence are shown in figure 2-9. These timing 
specifications are required in order to guarantee that the read/write heads position has stabilized prior 
to readina. 


DC POWER | 
~MOTOR ON | « 


~ DRIVE SELECT 


~ STEP 


—WRITE GATE 


—VALID*READ 
DATA 


L— 750 us min 


FIGURE 2-9 READ INITIATE TIMING 


2-7 


The timing of read data is shown in figure 2-10. The clock-to-clock interval (T) is 84s for FM and 
4us for MFM at 1.0M mode, 4s for FM and 2s for MFM at 2.0M mode. 


The encoding scheme of the recorded data can be either FM or MFM. 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 if the preceding bit cell or the current bit cell contains a data or clock bit. See figure 2-17. 


In the above-mentioned encoding schemes, clock bits are written at the start of their respective bit 
cells, and data bits at the centers of their bit cells. 


| | T | T/2 | T/2 | 


0.4428 £0.2us 
—> 


— READ DATA 


FIGURE 2-10 READ DATA TIMING 


CELLS ye | d 


BIT! oe 
CELLS ! d - 
Yi 6) 0 D Gc D e 


FIGURE 2-11 FM AND MFM CODE COMPARISONS 


2.4.3 —Write Protect 


This interface signal is provided by the drive to indicate to the user that a write protected diskette is 
inserted. The signal is logical zero level when it is protected. The drive will inhibit writing with a write - 
protect diskette inserted and notifies the interface. 


2-8 


2.4.4 —Track 00 


2.4.5 


The active or logical zero state of this interface signal indicates when the read/write head of the drive 
is positioned at track zero (the outermost track) and the stepper is locked on track. This signal is at a 
logical one level, or inactive state, when the read/write head is not at track 00. 


Note :_ This signal is enabled within 2.9 ms after receiving the —STEP signal. 
— TRACK 00 
— DIRECTION 
FIGURE 2-12 TRACK 00 TIMING 
~ Disk Change 


This interface signal is provided by the drive to indicate the condition that diskette is ejected and 
output when — DRIVE SELECT 1 line is activated. 


NOTE : When —MOTOR ON signal is active low, 100 ms delay is required after inserting media 
up to the —STEP signal to reset the — DISK CHANGE signal. 


— DRIVE SELECT | | | 


DISKETTE 


~ DISK CHANGE 


~STEP 


FIGURE 2-13 DISK CHANGE TIMING 


2-9 


2.5 


POWER INTERFACE 


The JU-257A6P requires only DC power for operation. DC power to the drive is provided via J2 
located on the component side of the PCB. The single DC voltages, their specifications and their J2 
pin designations are outlined in Table 2-1. The specifications outlined on current requirements are 
for one drive. For multiple drive systems, the current requirements are a multiple of the maximum 
current times the number of drives in the system. 


TABLE 2-1 DC POWER REQUIREMENTS 


2.5.1 


2.6 


POWER SEQUENCING 


~ Applying DC power to the JU-257A6P can be done in any sequence. However, during power up, the 


—WRITE GATE line must be held inactive or at a high level. 


FRAME GROUND AND SIGNAL GROUND 


There is a0Q Resistor between the aluminum base plate of the drive (= frame ground) and the signal 
ground of the control PCB. 
The aluminum base plate of the drive is the same electrical level as the signal ground of the control 


PCB. 


2-10 


2.7 SEQUENCE OF EVENTS 


The timing diagram shows the necessary sequence of events with associated timing requirements for 
proper position. 


_— nk eee OE 
POWER ON 


— MOTOR ON | 


| 750s ha 
—DRIVE SELECT 1 min 
~ VALID TRKOO —————————— oe 


AND | 
- WRITE 
PROTECT . 
oo 
Ope = l«— 2“ min 
—VALID INDEX et i ee eee 
| | 700ms max | 2S eeEREnEEEEEEE! 
— DIRECTION. 2 en 
SELECT | . 
<— 14s min 1usmin 
18 ms min 


1s -1ms—> 


ret | ‘ 750 4S min 

—WRITE GATE a ee ar 
| | 18 ms min - | 

—WRITE DATA | | etented YT 


2.0M-MODE 4 zs max ) | 2.0M-MODE 4 “#5 max 
1.0M-MODE 8 zs max 


: 1.0M-MODE 8 zs max 
| > L- 750 zs min 
—SIDE SELECT Te ea 
2.0M-MODE 100 zs min ; 
1.0M-MODE 200 zs min >| +—| peep 
—VALID . 
READ DATA | | | | 


18 ms 
min 
2usmin 


500ms min 


FIGURE 2-14 GENERAL CONTROL AND DATA TIMING REQUIREMENT 


SECTION [il 
ELECTRICAL CONNECTIONS 
3.1. INTRODUCTION 


The electrical interface between the JU-257A6P and the host system is via two connectors. The first 
connector, J1, provides the signal interface and the second connector, J2, provides the DC power. 


This section describes the physical connectors used on the drive and the recommended connectors to 
be used with them. See figure 3-1 for connector locations. 


UF CONNECTOR Ji 


Pi CONNECTOR 


HF 38-34D-2. 542 


POWER CONNECTOR 
12 


oe 
; so ?2 CONNECTOR 


AMP P/N 170204 - 2, P/M 171322-6 
FIGURE 3-1 INTERFACE CONNECTORS LOCATIONS 


3.2 Ji / P14 CONNECTOR (I/F CONNECTOR) 


Connection to Ji is through a PCB pin type connector. Pins are numbered 1 through 34 with the odd- 
numbered pins being the PCB side in a row. The recommended connectors for J1/P1 are shown in 
table 3-1. 


TABLE 3-1 RECOMMENDED P1 CONNECTORS 


P1 (HOST) MANUFACTURER 
HIF 3B-34D-2.54R HIROSE 
IMSA-9000S-34-G IRISO 


3-1 


3.3. J2/P2 CONNECTOR (POWER CONNECTOR) 


The DC power connector, J2, is mounted on the component side of the PCB and is located the right 
side of the stepper motor. J2 is a 4-pin TOKYO MICRO DEVICE Power connector P/N FJC01701B4. 
The recommended matching connector (P2) is AMP P/N 171822-4 utilizing AMP pins P/N 170204-2. 


J2 CONNECTOR PIN 


Pi] ssw 


34 


1 33 POWER SUPPLY 
J2 CONNECTOR 


J1 SIGNAL CONNECTOR 


A WARNING 


Supply only DC power 5.0V+ 10% for pin #1 and pin #2 & #3 serve as ground of the 
power connector (J2). Any adding or alteration of power source might damage the 


disk drive or diskette. 
Disassembly, modification and repair of the flexible disk drive are strictly prohibited. 


3-2 


SECTION IV 
DRIVE MOUNTING AND DIMENSIONS 
41 GENERAL 
The section contains the mechanical dimensions and mounting recommendations for the JU-257A6P. 
4.2 MOUNTING 
NOTE 


DO NOT MOUNT HORIZONTALLY WITH PCB ON THE UPPER SIDE. 
DO NOT MOUNT VERTICALLY WITH FRONT BEZEL FACING UP/DOWN. 


The drive can be mounted in either of the following positions (see Figure 4-1). 


Front Loading - mounted vertically with Push Button in either lower left or upper right positions. 
- mounted horizontally with PCB on the lower side. 


HORIZONTAL VERTICAL 


Rear side mounting holes are off-center of gravity. When you use these mounting holes, support the 
upper and bottom side of the FDD. 


WW 


rear side mounting holes 


FIGURE 4-1 RECOMMENDED MOUNTING POSITIONS 


4-1 


4.3 OUR RECOMMENDATION OF SCREW AND FIXING CONDITION 
a. Recommendation of screw 


Type : M3Pitcho.6mm 
Length : Insertlength @=3mm MIN. 5.5mm MAX 


System Bracket 


b. Recommendation of fixing torque 
3.5kgfcm to 4.0kgfcm 
c. Recommendation of torque driver's rotation speed. 


1000rpm MAX. 


4-2 


4.4 MECANICAL DIMENSIONS 


(40) ————>}«—— (25) —> 


(6.8) 


VO CONNECTOR (34P) 


. ; ; PUSH BUTTON 
I4— 2540.5 —Prt-— 32 +05 >) 


FIGURE 4-2 MECHANICAL DIMENSIONS 
4-3 


5.1 


5.2 


5.3 


SECTION V 
ERROR RECOVERY 

WRITE ERROR 

If an error occurs during a write operation, this error will be detected on the next revolution by doing a 
read operation (commonly called a “write check”). To correct the error, another write and write check 
operation must be done. If the write operation is not successful after 10 attempts have been made, a 
read operation should be attempted on another track. This is done to determine if the diskette or the 
drive is failing. If the error still persists, the diskette should be considered defective and discarded. 


READ ERROR 
Most errors that occur will be “soft” errors. Soft errors are usually caused by the following: 


a. Airborne contaminants passing between the read/write head and the disk. The contaminant 
will generally be removed by the diskette self-cleaning wiper 


b. Random electrical noise which usually lasts for a few microseconds 


c. Small defects in the written data and/or track not detected during the write operation which 
may cause a soft error during a read 


The following procedure is recommended to recover from errors: 
a. Reread the track 10 times or until such time as the data is recovered 


b. If data is not recovered after using step “a”, access the head to the adjacent track in the same 
direction previously moved. Return to the desired track 


c. Repeat step “a” 
d. If data is not recovered, the error is not recoverable 
SEEK ERROR 
Seek errors are detected by reading the ID field after the seek is completed. The ID field contains the 


track address. If a seek error is detected, the host system should issue a recalibrate operation (step 
out until the —TRACK 00 line goes active) and seek back to the original track. 


SECTION VI 
RECORDING FORMAT 


6.1 GENERAL 


The format of the data recorded on the disk is totally a function of the host system. Data can be 
recorded on the disk using FM or MFM encoding. In these encoding techniques, clock bits are written 
at the start of their respective bit cells and data bits at the centers of their bit cells. 


Byte 


A byte, when referring to serial data (being written onto or read from the disk drive), is defined as eight 
consecutive bit cells. The most significant bit cell is defined as bit cell 0 and the least significant bit cell 
is defined as bit cell 7. When reference is made to a specific data bit (i.e., ... data bit 3), it is with 
respect to the corresponding bit cell (bit cell 3). 


During a write operation, bit cell 0 of each byte is transferred to the disk drive first with bit cell 7 being 
transferred last. Correspondingly, the most significant byte of data is transferred to the disk first and 
the least significant byte is transferred last. 


When data is being read back from the drive, bit cell 0 of each byte will be transferred first with bit cell 
7 last. As with reading, the most significant byte will be transferred first from the drive to the user. 


Figure 6-1 illustrates the relationship of the bits within a byte and figure 6-2 illustrates the relationship 
of the bytes for read and write data. 


CELL | BITCELL| BITC 


BIT CELL | BIT CELL | BIT CELL| BIT 
1 2 3 6 


ELL | BITCELL| BIT CELL 
7 8 


BINARY HEXADECIMAL 
REPRESENTATION : REPRESENTATION « 
DATA BITS 1 1 0 0 1 0 1 0 DATA BITS (CA) 
CLOCK BITS 1 1 1 1 1 1 1 1 CLOCK BITS (FF) 
FIGURE 6-1 BYTE (FM ENCODING) 
BYTE} BYTE BYTE 


0 1 2 3 4 5 6 7 8 9 10 11 12 | 13 | 14 7 15 f 16 7 17 


t | t 


BIT CELL 0 OF BYTE OIS FIRST DATA BIT CELL 7 OF BYTE 17 1S LAST 
TO BE SENT TO THE DRIVE WHEN DATA TO BE SENT TO THE ORIVE 
WRITING AND FROM THE DRIVE WHEN WRITING AND FROM THE 
WHEN READING. DRIVE WHEN READING. 


FIGURE 6-2. DATA BYTES 


6.2 JU-257A6P SOFT SECTORS RECORDING FORMAT 
In this format, the user system may record one long record or several smaller records. Each track is 


started by a physical index pulse and then each record is preceded by a unique recorded identifier. 
This type of recording is called soft sectoring. 


Index 
Detected \, 


Sector 02 


Sector 01 


& 


ID Field Data Field — 


Sector 
{Track 


| 27 | 44 | | 16 | 
1 2 [a2lral{ 9 | 
58 | 37 | 15 | 
” 22 
(decimal) 2 ae 


— These data bytes include missing clock. 
*2 ID Field. 
*3 CRCCheck byte : G(Xj=i+xX5+x"44x'6 


N 
oa 
ar 


Double 
density 
(MFM) 


FIGURE 6-3. IBM TYPE FORMAT (1.0M-MODE) 


6-2 


Index 
Detected \, 


Sector 02 


Last Sector 01 


Sector 


ID Field 


Data Field = 


Sector 


peas 1147] | 10 
| 54 [4s0| | 32 | 
1512] 2 [84 [510] | 18 | 
f1024{_ 116 [3a4[ | 10 | 

FB* 
Fe* 


Single 
density 
(FM) 


n 


no 


Double 
density 
(MFM) 


; These data bytes include missing clock. 
*2, ID Field. 
*3 CRC Check byte : G(X)=1+X5+x'?4+x"® 


FIGURE 6-4 IBM TYPE FORMAT (2.0M-MODE) 


7.1 


7.2 


7.3 


SECTION VII 
OPERATION PROCEDURES 


INTRODUCTION 

The JU-257A6P is designed for ease of operator use to facilitate a wide range of operator-oriented 
applications. The following paragraphs provide a guide for handling procedures on the diskette and 
the flexible disk drive. 

DISKETTE LOADING 

To load the diskette, insert the diskette auto-shutter first, with the label facing up or opposite the eject 
button in HORIZONTAL mounting applications. Push in the diskette. A mechanical interlock ensures 
proper diskette insertion. 

if the diskette fails to load, press the eject button, then reinsert the diskette. 

To remove the diskette, push the eject button. The diskette will automatically eject. 


DISKETTE HANDLING 


To protect the diskette, the same care / handling procedures specified for computer magnetic tape 
apply. These precautionary measures are as follows: 


a. Diskette not intended for immediate use should be stored in the box. 


b. Keep diskette away from magnetic fields and from ferromagnetic materials which might 
become magnetized. Strong magnetic fields can distort recorded data on the disk. 


c. Place ID labels in correct location, never use in reverse. 
d. Do not use erasers. 
f. Heat and contamination from carelessly dropped ash could damage diskette. 


e. Do not expose diskette to heat or sunlight. 


HEAD WINDOW AUTO SHUTTER 
OPENING WINDOW 0.13 in. 
3.3 mm 


AUTO SHUTTER i eee 


INNER TRACK 


TRACK 79 3.7 in. 


94.0 mm 


WRITE PROTECT 


High Densi I 
eens Sieg ist Seco See 
90.0 mm ; 


FIGURE 7-1 DISKETTE NOMENCLATURE 


7.4 WRITE PROTECT FEATURE 


The diskette comes with a mechanical write protect tab. To be a write protected diskette, slide the 
mechanical tab as shown in Figure 7-2 to uncover the write protect hole. 


WRITE ENABLED SLIDE MECHANICAL TAB 
HOLE CLOSED AS SHOWN TO OPEN HOLE 
(WRITE PROTECTED) 
BOTTOM VIEW 


FIGURE 7-2. WRITE PROTECT OPERATION