Page 1: ...ST251 ST251 RIST277R Product Manual February 3 1987 36035 001 Revision A 920 Disc Drive Scotts Valley CA 95066 4544 USA Telephone 408 438 6550 Telex 176455 SEAGATE SCVL c5S seagate...
Page 2: ...copyrighted with all rights reserved This manual may not be copied in whole or in part without written consent of Seagate Technology Seagate reserves the right to change without notice the specificat...
Page 3: ...S 1 7 2 2 ST2S1R 1 S 1 7 2 3 ST277R 1 S 1 8 Environmental Specifications 1 S 1 8 1 Ambient Temperature 1 S 1 8 1 1 ST251 1 S 1 8 1 2 ST251R 277R 1 5 1 8 2 Temperature Gradient 1 5 1 8 3 Relative Humid...
Page 4: ...VE CONFIGURATION 2 1 2 1 Drive Configuration Shunt J7 2 1 2 2 Drive Select 2 2 2 2 1 Daisy Chain Radial Drive Configurations 2 2 2 3 Write Fault Latch Options JP1 and J7 2 2 2 4 DC Unsafe Option JP2 2...
Page 5: ...1 9 Figure 2 Typical Power On Sequence 1 9 Figure 3 Drive Mounting Dimensions 1 12 Figure 4 Read Write Timing 1 14 Figure 5 Buffered Seek Timing 1 15 Figure 6 Auto Truncation Timing 1 15 Figure 7 Host...
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Page 7: ...INTRODUCTION This manual supports the ST2511251 R 277R disc drives It supercedes and replaces the ST251 Product Manual 36016 001 Rev B ST2511251RI277R Product Manual Rev A vii...
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Page 9: ...10 416 15 624 15 624 1 1 2 FORMATTED CAPACITY Megabytes Per Drive 42 8 43 6 65 5 Bytes Per Cylinder 52 224 53 248 79 872 Bytes Per Track 8 704 13 312 13 312 Bytes Per Sector 512 512 512 Sectors per Tr...
Page 10: ...ge Latency 8 msec max 40 msec max 95 msec max 8 33 msec 1 3 STEP PULSE PERIOD AND SEEK METHOD The step signal is a 2psec minimum width pulse which initiates read write head motion The step pulse perio...
Page 11: ...ECORDING METHODS The 8T251 is designed to operate with the 8T412 interface with MFM encoding at 5 0 megabit sec data transfer rate Caution Operation of an MFM drive with an RLL controller Is not ap pr...
Page 12: ...cations the data separator must provide at least 40 dB of bit jitter reduction at 2F with an offset error of less than 1 5 nsec shift from the center of the data window 1 7 2 MEDIA DEFECTS A media def...
Page 13: ...five 6S defects total per drive 1 8 ENVIRONMENTAL SPECIFICATIONS 1 8 1 AMBIENT TEMPERATURE 1 8 1 1 ST251 Operating Nonoperating 1 8 1 2 ST251 R 277R Operating Nonoperating 1Qoe to 4soe SOoF to 113 F 4...
Page 14: ...are based on a 11 msec half si ne wave shock pulse The nonoperating specifications assume that the read write heads are positioned in the shipping zone 1 8 5 1 OPERATING SHOCK Maximum shock without i...
Page 15: ...ATION Maximum vibration at the following frequencies without incurring physical damage or degradation in performance Freq 5 22 Hz 22 300 Hz 300 22 Hz 22 5 Hz Vibration 0 020 in Displacement double amp...
Page 16: ...nd 12 6 VDC applied sea level and spindle rotating Maximum seek currents are measured on repetitive 3 track buffered seeks with a one half spindle rotation between each seek 12 VDC Voltage Tolerance i...
Page 17: ...GURE 2 Typical Power On Sequence 1 03A 5VDC 4SA 12 VDC rr rr _ _ 1 1 1 DC ON I 12 sec 1yp j r ROTATIONAL SPEED I REGULATED O S r 10 sec typo j TRACK J ____________ J l READY 20 msec max H I 1 SEEK COM...
Page 18: ...d by TUV Rheinland North America 1 10 FCC CERTIFICATION WARNING The ST251 is certified to comply with the limits for a Class B computing device pursuant to Subpart J of Part 15 of FCC rules Only devic...
Page 19: ...hould consult your dealer or an experienced radiol television technician for additional suggestions You may find helpful the following booklet prepared by the Federal Comunications Com mission How to...
Page 20: ...uring mechanical shock or vibration I FIGURE 3 Drive Mounting Dimensions 1 95 010 495 25 5e75 010 49 22 25 I _ 1 87 03 f 47 50 76tl 3 12 t 03 79 25 16 NOTE The mounting screws must not extend Inside t...
Page 21: ...brate to Track 0 The heads may also be parked in the shipping zone by issuing a seek command to the maximum data cylinder plus one 820 1 12 AUTO TRUNCATION The drive will enter the auto truncation mod...
Page 22: ...drive tim ing FIGURE 4 Read Write Timing DRIVE SELECT HEAD SELECT H J L 40 nsec min 95 nsec max 8 j lsec max I I Head Switching rum n MFM RLL VALID j READ DATA 1 1 WRITE GATE 200 nsec typ bit cell 8 I...
Page 23: ...r H 3 sec min 2001lsec max SEEK COMPLETE L 100 nsec mm DRIVE SELECT 100 nsec min r 1 1 40 msec avg 95 msec max FIGURE 6 Auto Truncation Timing 1 Excessive Step Pulses Recognized TRACK 0 SEEK 9 msec ty...
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Page 25: ...t line and any options Figure 7 illustrates J7 and indicates pin 1 FIGURE 7 Host Drive Interface Connectors Optional Groundl 1l Point PIe_ note the position of the Inltalled Inaulatl 1l Willie JP2 DC...
Page 26: ...chain configuration the last drive in a chain must have the resistor termination pack installed 2 3 WRITE FAULT LATCH OPTIONS JP1 AND J7 These options allow the user to configure the Write Fault reset...
Page 27: ...Fault signal will be false 2 4 DC UNSAFE OPTION JP2 JP2 has two jumper pads and when a jumper is installed a DC unsafe condition will cause a Write Fault to be sent to the interface Use Fig ure 7 on p...
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