Page 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
ST3491 Family:
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
ST3250A, ST3291A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
ST3391A, ST3491A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
AT Interface Drives
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
Product Manual
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
Page 2
Page 3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
ST3491 Family:
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
ST3250A, ST3291A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
ST3391A, ST3491A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
AT Interface Drives
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
Product Manual
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
Page 4
© 1994 Seagate Technology, Inc. All rights reserved
Publication Number: 36254-004, Rev. B
April 1994
Seagate
®
, Seagate Technology® and the Seagate logo are registered
trademarks of Seagate Technology, Inc. SeaCache is a trademark of
Seagate Technology, Inc. Other product names are trademarks or registered trademarks of their owners.
Seagate reserves the right to change, without notice, product offerings
or specifications. No part of this publication may be reproduced in any
form without written permission from Seagate Technology, Inc.
Page 5
ST3491 Family AT Product Manual, Rev. B iii
Contents
1.0 Specification summary . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Formatted capacity . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Physical organization . . . . . . . . . . . . . . . . . . . 1
1.1.2 Recommended logical configuration . . . . . . . . . . . 2
1.2 Drive dimensions . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Functional specifications . . . . . . . . . . . . . . . . . 3
1.3 Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 Seek time . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.6 Auto-park . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.7 Shock and vibration . . . . . . . . . . . . . . . . . . . . . . 4
1.8 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.8.1 Ambient temperature . . . . . . . . . . . . . . . . . . . 5
1.8.2 Temperature gradient . . . . . . . . . . . . . . . . . . . 5
1.8.3 Relative humidity . . . . . . . . . . . . . . . . . . . . . 5
1.8.4 Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.9 Power requirements . . . . . . . . . . . . . . . . . . . . . . 6
1.9.1 Input noise . . . . . . . . . . . . . . . . . . . . . . . . 6
1.9.2 Start and stop time . . . . . . . . . . . . . . . . . . . . 6
1.9.3 Idle and Standby timers . . . . . . . . . . . . . . . . . 7
1.9.4 Power-management modes . . . . . . . . . . . . . . . 7
1.9.5 Power consumption . . . . . . . . . . . . . . . . . . . 9
1.10 Agency listings . . . . . . . . . . . . . . . . . . . . . . . . 9
1.11 FCC verification . . . . . . . . . . . . . . . . . . . . . . 10
2.0 Hardware description . . . . . . . . . . . . . . . . . . . . . . 11
2.1 Handling and static-discharge precautions . . . . . . . . . 11
2.2 Drive mounting . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Drive I/O connector . . . . . . . . . . . . . . . . . . . . . 15
3.0 Interface description . . . . . . . . . . . . . . . . . . . . . . 17
Page 6
iv ST3491 Family AT Product Manual, Rev. B
3.1 AT interface connector pin assignments . . . . . . . . . . 17
3.2 Bus signal levels . . . . . . . . . . . . . . . . . . . . . . . 17
3.3 Configuration jumpers . . . . . . . . . . . . . . . . . . . . 19
3.3.1 Factory test configuration . . . . . . . . . . . . . . . . 20
3.3.2 Master/slave configuration . . . . . . . . . . . . . . . 20
3.3.3 No DASP– configuration . . . . . . . . . . . . . . . . 20
3.4 Cable select configuration . . . . . . . . . . . . . . . . . . 21
3.5 Drive activity LED . . . . . . . . . . . . . . . . . . . . . . 22
3.6 Supported AT commands . . . . . . . . . . . . . . . . . . 23
3.6.1 Identify Drive command (EC
3.6.2 Set Features command (EF
3.6.3 Set Multiple Mode command (C6
3.6.4 Read Multiple command (C4
3.6.5 Write Multiple command (C5
) . . . . . . . . . . . . . 25
H
) . . . . . . . . . . . . . 28
H
) . . . . . . . . . . 30
H
) . . . . . . . . . . . . . 30
H
) . . . . . . . . . . . . . 31
H
3.7 Onboard drive diagnostics . . . . . . . . . . . . . . . . . . 32
3.8 ECC performance tests . . . . . . . . . . . . . . . . . . . 32
3.9 Supported BIOS . . . . . . . . . . . . . . . . . . . . . . . 33
Page 7
ST3491 Family AT Product Manual, Rev. B v
Figures
Figure 1. Typical startup current profile . . . . . . . . . . . . . . . . 8
Figure 2. Standard mounting dimensions . . . . . . . . . . . . . . 13
Figure 3. Metric mounting dimensions . . . . . . . . . . . . . . . . 14
Figure 4. AT interface drive connector . . . . . . . . . . . . . . . . 15
Figure 5. AT connector pin assignments . . . . . . . . . . . . . . 18
Figure 6. Connectors and jumpers . . . . . . . . . . . . . . . . . 19
Figure 7. Connecting cable-selected drives . . . . . . . . . . . . . 21
Page 8
Page 9
ST3491 Family AT Product Manual, Rev. B 1
1.0 Specification summary
1.1 Formatted capacity
The drive is low-level formatted at the factory. You cannot low-level format
the drive.
ST3250A ST3291A
Formatted capacity (Mbytes*) 213.9 272.7
Total sectors 417,792 532,700
ST3391A ST3491A
Formatted capacity (Mbytes*) 341.3 428.1
Total sectors 666,624 836,070
* One megabyte equals one million bytes.
1.1.1 Physical organization
ST3250A ST3291A
Heads 2 4
Discs 1 2
ST3391A ST3491A
Heads 4 4
Discs 2 2
Page 10
2 ST3491 Family AT Product Manual, Rev. B
1.1.2 Recommended logical configuration
You can operate the drive using many different logical configurations,
provided the number of sectors per track does not exceed 256. However,
in DOS the number of sectors per track must be less than or equal to 63.
When establishing the logical configuration, set the number of sectors
per track and the number of heads to satisfy the following relationship:
16
≤ (sectors per track) x (heads) ≤ 4,096
When you configure the drive in CMOS, the total sectors cannot exceed
the physical capacity of the drive. The total sectors is determined by the
following formula:
total sectors = (logical heads) x (logical sectors per track) x (logical cylinders)
To maximize the capacity of the drive, the following geometry is recommended:
ST3250A ST3291A
Cylinders 1,024 761
Heads 12 14
Sectors per track 34 50
ST3391A ST3491A
Cylinders 768 899
Heads 14 15
Sectors per track 62 62
The drive is configured in translation mode. You can verify the number
of cylinders, sectors per track and heads by using the Identify Drive (EC
command. See the
tion number 36111-
Seagate ATA Interface Reference Manual
xxx
, for details about the Identify Drive command.
, publica-
H
1.2 Drive dimensions
Height (max) 1.00 inch (25.4 mm)
Width (max) 4.02 inches (102.1 mm)
Depth (max) 5.77 inches (146.6 mm)
Weight (max) 1.3 lb (0.59 Kg)
)
Page 11
ST3491 Family AT Product Manual, Rev. B 3
1.2.1 Functional specifications
Interface AT
Internal data transfer rate (Mbits/sec) 18.7 to 32*
External data transfer rate (Mbytes/sec) 11.1**
Spindle speed ± 0.5% (RPM) 3,811
SeaCache buffer (Kbytes) 120
Zone Bit Recording method RLL (1,7)
Bytes per sector
Recording density, max (BPI) 55,200
Flux density, max (FCI) 41,400
Track density, max (TPI) 3,081
* The internal data transfer rate for the ST3491A is 18.7 to 32.
** This is the external data transfer rate during a cache transfer. When
the drive is not using the cache, the transfer rate is 5.0 Mbytes per
second.
512
1.3 Reliability
The MTBF specification assumes nominal power at sea level with an
ambient temperature of 25°C.
Nonrecoverable errors 1 per 10
MTBF 300,000 power on hours
Contact start-stop (CSS) 40,000 cycles
MTTR 30 minutes
Service life 5 years
13
bits read
1.4 Acoustics
Sound pressure is measured at idle from 1 meter above the drive top
cover.
Sound pressure, typ 29 dBA
Sound pressure, max 33 dBA
Page 12
4 ST3491 Family AT Product Manual, Rev. B
1.5 Seek time
All performance measurements are taken using a 25 MHz 486 AT
computer (or faster) with a 8.3 MHz I/O bus. The measurements are
taken with nominal power at sea level and 25°C ambient temperature.
The specifications in the table below are defined as follows:
• Track-to-track seek time is an average of all possible single-track
seeks in both directions.
• Average seek time is a true statistical random average of at least 5,000
measurements of seeks between random tracks, less overhead.
• Full-stroke seek time is one-half the time needed to seek from the first
data cylinder to the maximum data cylinder and back to the first data
cylinder. The full-stroke average is determined by measuring 100
full-stroke seeks in both directions.
Track-to-track
Model
ST3250A 5 15 34 7.87
ST3291A 5 13 32 7.87
ST3391A 5 14 33 7.87
ST3491A 5 15 34 7.87
typ (msec)
Average
typ (msec)
Full-stroke
typ (msec)
Latency
(msec)
1.6 Auto-park
Upon power-down, the read/write heads automatically move to the
shipping zone. The heads park inside the maximum data cylinder. When
power is applied, the heads recalibrate to track 0.
1.7 Shock and vibration
Shock measurements are based on an 11 msec, half sine wave shock
pulse, not to be repeated more than twice per second. The specifications
in the table below are defined as follows:
• During normal operating shock and vibration, the drive sustains no
physical damage and reads and writes data without errors.
Page 13
ST3491 Family AT Product Manual, Rev. B 5
• During abnormal operating shock and vibration, the drive sustains no
physical damage, but performance is adversely affected.
• During nonoperating shock and vibration, the read/write heads are in
the shipping zone and the drive sustains no physical damage.
Normal
operating
Shock 2 Gs 10 Gs 75 Gs
5–22 Hz vibration
22–500 Hz vibration 0.50 Gs 0.75 Gs 4.00 Gs
0.020-inch
displacement
Abnormal
operating Nonoperating
0.030-inch
displacement
0.160-inch
displacement
1.8 Environment
The acceptable environmental conditions for the drive are specified
below. The specifications in this section are defined as follows:
• Operating specifications assume that the drive is powered up.
• Nonoperating specifications assume that the drive is packaged as it
was shipped from the factory.
1.8.1 Ambient temperature
Operating 5° to 55°C (41° to 131°F)
Nonoperating –40° to 60°C (–40° to 140°F)
1.8.2 Temperature gradient
Operating (max) 20°C per hour (36°F per hour)
Nonoperating (max) 30°C per hour (54°F per hour)
1.8.3 Relative humidity
Operating 8% to 80% noncondensing
Maximum wet bulb 29.4°C (85.0°F)
Nonoperating 5% to 95% noncondensing
Maximum wet bulb 40.0°C (104°F)
Page 14
6 ST3491 Family AT Product Manual, Rev. B
1.8.4 Altitude
Operating –1,000 ft to 10,000 ft (–305 m to 3,050 m)
Nonoperating –1,000 ft to 40,000 ft (–305 m to 12,200 m)
1.9 Power requirements
Except during a write operation, you can apply power to the drive or
remove power from the drive in any sequence without losing data or
damaging the drive.
1.9.1 Input noise
The drive is expected to operate with a maximum of 150 mV peak-to-peak
triangular wave injected noise at the power connector. The frequency is
10 Hz to 20 MHz with equivalent resistive loads.
+5V +12V
Voltage tolerance
including noise
± 5% ± 5%
± 10% during spinup
1.9.2 Start and stop time
After 10 seconds, the drive is ready. Typical and maximum start and stop
times are shown in the following table. See Figure 1 on page 8 for the
typical startup current profile.
Typical Maximum
Start time 7 sec 10 sec
Stop time 6 sec 9 sec
Page 15
ST3491 Family AT Product Manual, Rev. B 7
1.9.3 Idle and Standby timers
The drive can enter the Idle mode or the Standby mode by either of two
methods:
• The computer sends either the Idle Immediate command or the
Standby Immediate command.
• The Idle timer or the Standby timer counts down to zero.
At power-on, the Idle and Standby timers are disabled; this is the default
mode of operation set at the factory. You can set the timer delays using
the computer setup utility. If the Idle timer is enabled, each time the drive
completes a read, write or seek, the drive reinitializes the Idle timer and
it begins counting down from the specified delay to zero.
If the Idle timer reaches zero before any drive activity is required, the
drive switches to the Idle mode. Then, if the Standby timer is enabled,
that timer begins counting down. For details, refer to the
Interface Reference Manual
In both the Idle and Standby modes, the drive accepts all commands and
returns to the Active mode any time disc access is necessary.
, publication number 36111-
Seagate ATA
xxx
.
1.9.4 Power-management modes
The following power-management modes are supported by the drive:
• Active mode. The drive is seeking, reading or writing.
• Idle mode. When the drive receives an Idle Immediate command, or
the idle timer counts down to zero, the drive enters the Idle mode. In
Idle mode, the spindle remains up to speed and the heads are parked
in the shipping zone. The SeaCache buffer remains enabled, and
the drive accepts all commands and returns to the Active mode
whenever a seek, read or write operation is needed.
• Standby mode. When the drive receives a Standby Immediate com-
mand, or the standby timer has counted down to zero, the drive enters
the Standby mode. In the Standby mode, the SeaCache buffer remains enabled, the heads are parked in the shipping zone and the
spindle is stopped. The drive accepts all commands and returns to the
Active mode whenever a seek, read or write operation is needed.
(
continued
)
Page 16
1 2 3 4
5V
12V
Current (mA)
900
800
700
600
500
400
300
200
100
0
0
Time (seconds)
5
1000
8 ST3491 Family AT Product Manual, Rev. B
Figure 1. Typical startup current profile
(
continued from previous page
)
• Sleep mode. When the drive receives a Sleep Immediate command,
it enters the Sleep mode. The heads are parked in the shipping zone
and the spindle is at rest. When a hard reset or soft reset is sent from
the computer, the drive returns to the Active mode. After a soft reset,
all current emulation and translation parameters remain intact.
Page 17
ST3491 Family AT Product Manual, Rev. B 9
1.9.5 Power consumption
Power consumption is measured according to the following guidelines:
• All measurements are taken at sea level with an ambient temperature
of 25°C.
• All typical measurements are taken using nominal voltages; the peak
startup power is measured using the nominal voltages.
• Seeking current measurements are taken using an RMS meter while
the drive is randomly seeking with two spindle rotations between each
seek.
Mode
Spinup (peak) 1.200 0.300 8.000 **
Active
Seeking (typ) 0.290 0.180 4.400
Read/write (typ)
Idle* (typ)
Standby* (typ) 0.020 0.080 0.640
Sleep* (typ) 0.020 0.065 0.570
* These power dissipation values apply only when power management
is enabled. To enable power management, use the computer setup
utility.
** Spinup power is averaged over 7 seconds.
Current (amps)
Power (watts)
+12V +5V
0.150 0.280 3.200
0.115 0.080 1.800
1.10 Agency listings
This drive is listed with agencies as follows:
• UL 1950
• CSA C22.2 No. 0-M91 and CSA C22.2 No. 950-M89
• EN 60950/10.92 as tested by TUV-Rheinland, North America
Page 18
10 ST3491 Family AT Product Manual, Rev. B
1.11 FCC verification
The ST3491 family drives are intended to be contained solely within a
personal computer or similar enclosure (not attached to an external
device). As such, a drive is considered to be a subassembly even when
individually marketed to the customer. As a subassembly, no Federal
Communications Commission authorization, verification or certification
of the device is required.
Seagate Technology, Inc. has tested these drives in an enclosure as
described above to ensure that the total assembly (enclosure, disc drive,
motherboard, power supply, etc.) does comply with the limits for a
Class B computing device, pursuant to Subpart J of Part 15 of the FCC
rules. Operation with noncertified assemblies is likely to result in interference to radio and television reception.
Radio and television interference. This equipment generates and uses
radio frequency energy and, if not installed and used in strict accordance
with the manufacturer’s instructions, may cause interference to radio and
television reception.
This equipment is designed to provide reasonable protection against
such interference in a residential installation. However, there is no
guarantee that interference will not occur in a particular installation. If this
equipment does cause interference to radio or television, which can be
determined by turning the equipment on and off, you are encouraged to
try one or more of the following corrective measures:
• Reorient the receiving antenna.
• Move the device to one side or the other of the radio or TV.
• Move the device farther away from the radio or TV.
• Plug the equipment into a different outlet so that the receiver and
computer are on different branch outlets.
If necessary, you should consult your dealer or an experienced radio/television technician for additional suggestions. You may find helpful the
following booklet prepared by the Federal Communications Commission:
How to Identify and Resolve Radio-Television Interference Problems.
This booklet is available from the Superintendent of Documents, US
Government Printing Office, Washington, DC 20402. Refer to publication
number 004-000-00345-4.
Page 19
ST3491 Family AT Product Manual, Rev. B 11
2.0 Hardware description
The ST3491 family drives use the industry-standard AT interface. These
drives support 16-bit data transfers and DMA and PIO modes. (See Set
Features command description.) You can connect up to two drives on
the same bus using a daisy-chain cable.
2.1 Handling and static-discharge precautions
After you unpack the drive, and before you install it in a computer, be
careful not to damage it through mishandling. Observe the following
standard handling and static-discharge precautions:
Caution:
• Keep the drive in its static-shielded bag until you are ready to complete
the installation. Do not attach any cables to the drive while it is in its
static-shielded bag.
• Before handling the drive, put on a grounded wrist strap, or ground
yourself frequently by touching the metal chassis of a computer that
is plugged into a grounded outlet. Wear a grounded wrist strap
throughout the entire installation procedure.
• Handle the drive by its edges or frame only.
• The drive is extremely fragile—handle it with care. Do not press down
on the drive top cover.
• Always rest the drive on a padded, antistatic surface until you mount
it in the computer.
• Do not touch the connector pins or the printed circuit board. Do not
touch the printed circuit cable between the circuit board and the
head/disc assembly.
• Avoid wool or synthetic clothing, carpeting, plastics, and Styrofoam;
these items cause static discharge.
• Do not remove the factory-installed labels from the drive or cover them
with additional labels. If you do, you void the warranty. Some factoryinstalled labels contain information needed to service the drive. Others
are used to seal out dirt and contamination.
Page 20
12 ST3491 Family AT Product Manual, Rev. B
2.2 Drive mounting
You can mount the drive in any orientation using either the bottom or the
side mounting holes, as described below. Figure 2 on page 13 and Figure
3 on page 14 show different dimension drawings for standard and metric
drives, respectively.
Note. The only difference between standard and metric drives is the
position of the mounting holes. The overall size of the drives is
the same.
• Standard-size drives have an “S” stamped on the frame runner and
accept 6-32 UNC screws.
• Metric drives have an “M” stamped on the frame runner and accept
M3 screws.
Bottom mounting holes. Insert four mounting screws not more than
0.20 inches (6 full turns) into the drive frame.
Side mounting holes. Insert four mounting screws not more than
0.13 inches (4 full turns) into the drive frame.
Caution. To prevent damage to the drive:
• Use only mounting screws of the correct size and length.
• Lightly tighten the mounting screws—do not apply more than 6 inch-lb
of torque.
Page 21
Four #6-32 UNC-2B mounting holes
1.75 ± 0.0102.375 ± 0.025
4.000 ± 0.010
2.362 ± 0.010
0.630 ± 0.025
0.250 ± 0.010
5.77 max
3.750± 0.030
4.02 max
0.15 ± 0.01
Six #6-32 UNC-2B mounting holes
0.030
1.000 max
ST3491 Family AT Product Manual, Rev. B 13
In Figure 2, the dimensions are shown in inches. This figure for standard-size drives shows the mounting holes in different positions when
compared with metric drives shown in Figure 3 on page 14.
Figure 2. Standard mounting dimensions
Page 22
Four M3 × 0.5 mounting holes
70.002 ± 0.25430.988
± 0.635
89.992 ± 0.254
59.995 ± 0.254
21.006 ± 0.635
4.978 ± 0.254
146.56 max
93.98 ± 0.762
102.108 max
3.81 ± 0.254
Six M3 × 0.5 mounting holes
0.762
25.4 max
14 ST3491 Family AT Product Manual, Rev. B
In Figure 3, the dimensions are shown in millimeters. This figure shows
the mounting holes in different positions when compared with Figure 2
on page 17.
Figure 3. Metric mounting dimensions
Page 23
0.70 ± 0.010
1.90
0.025
± 0.002
0.100 typ
0.230 ± 0.003
2.00
0.235 ± 0.025
0.160
0.070 ± 0.010
0.100 ± 0.010
0.025 ± 0.002
Dimensions are in inches
ST3491 Family AT Product Manual, Rev. B 15
2.3 Drive I/O connector
The drive interface connector has 40 pins, with 2 rows of 20 male pins
on 100-mil centers.
Use a 40-pin, nonshielded cable connector with 2 rows of 20 female
contacts on 100-mil centers. The maximum cable length is 18 inches
(457 mm). Strain relief is recommended. The recommended part numbers are listed below. The connector is shown in Figure 2.
AMP 1-499496-0
Du Pont 66900-040
Figure 4. AT interface drive connector
Page 24
Page 25
ST3491 Family AT Product Manual, Rev. B 17
3.0 Interface description
The drive complies with all ATA interface specifications. The interface
consists of single-ended, TTL-compatible receivers and drivers communicating through a 40-conductor flat-ribbon, nonshielded cable with a
maximum length of 18 inches (0.46 meters) using an asynchronous
interface protocol. The drivers can sink up to 24 mA and drive a load up
to 300 pF.
3.1 AT interface connector pin assignments
The signal name and signal direction for each I/O connector pin is
described in Figure 5 on page 18. See the
Reference Manual
scription of each pin.
Signal names are in upper case. If the signal name is followed by a minus
sign (–), the signal is active low. Otherwise, the signal is active high.
Note. The drive does not use the SPSYNC– signal.
, publication number 36111-
3.2 Bus signal levels
Seagate ATA Interface
xxx
, for a complete de-
Signals that the drive sends have the following output characteristics,
measured at the drive connector.
Logic low 0 to 0.4V
Logic high 2.5 to 5.25V
Signals that the drive receives must have the following input characteristics, measured at the drive connector.
Logic low 0 to 0.8V
Logic high 2.0 to 5.25V
Page 26
Drive 0
(master)
Drive 1
(slave)
28
34
39
28
34
39
CSEL
PDIAG
–
DASP–
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Host Reset
Ground
Host Data Bus Bit 7
Host Data Bus Bit 8
Host Data Bus Bit 6
Host Data Bus Bit 9
Host Data Bus Bit 5
Host Data Bus Bit 10
Host Data Bus Bit 4
Host Data Bus Bit 11
Host Data Bus Bit 3
Host Data Bus Bit 12
Host Data Bus Bit 2
Host Data Bus Bit 13
Host Data Bus Bit 1
Host Data Bus Bit 14
Host Data Bus Bit 0
Host Data Bus Bit 15
Ground
(No Pin)
DMA Request
Ground
Host I/O Write
Ground
Host I/O Read
Ground
I/O Channel Ready
Cable Select
DMA Acknowledge
Ground
Host Interrupt Request
Host 16 Bit I/O
Host Address Bus Bit 1
Passed Diagnostics
Host Address Bus Bit 0
Host Address Bus Bit 2
Host Chip Select 0
Host Chip Select 1
Drive Active or
Slave Present
Ground
Host pin # and signal description
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
*28
29
30
31
32
33
*34
35
36
37
38
*39
40
Drive pin #
Signal name
18 ST3491 Family AT Product Manual, Rev. B
–
Reset
Ground
DD7
DD8
DD6
DD9
DD5
DD10
DD4
DD11
*Indicates master-slave signals (details shown below).
DD3
DD12
DD2
DD13
DD1
DD14
DD0
DD15
Ground
(removed)
DMARQ
Ground
–
DIOW
Ground
–
DIOR
Ground
IORDY
CSEL
DMACK
IOCS16
Ground
INTRQ
DA1
PDIAG
DA0
DA2
CS1FX
CS3FX
DASP
Ground
–
–
–
–
–
–
Host
28
34
39
Figure 5. AT connector pin assignments
Page 27
Front
4-pin
power connector
8-pin
options jumper block
Front
Cable select
40-pin
AT interface
connector
4
3
2
1
Circuit board
+5V
+5V return
+12V return
+12V
The drive is a master; a
slave is present, but it does
not have a DASP− signal.
Available
2-pin
header
Drive activity
LED
3-pin
power connector
1
2
3
Keyway
Ground
+12V
+5V
The drive is a master;
a slave is present, but
it is not ATA-compatible.
The drive is a slave to an
ATA-compatible master.
The drive is a master;
the slave is either an
ST3491 family drive or
another ATA-compatible
drive, or there is no slave.
21436
587
Factory test (Do not use.)
Circuit
board
ST3491 Family AT Product Manual, Rev. B 19
3.3 Configuration jumpers
Figure 6 shows the location of the options jumper block. The jumper block
accepts 2-mm (0.079-inch) jumpers.
Caution. If you use a jumper that is not the correct size, you may damage
the jumper block and the jumper. Use the jumpers supplied
with the drive.
Figure 6. Connectors and jumpers
Page 28
20 ST3491 Family AT Product Manual, Rev. B
3.3.1 Factory test configuration
Do not install jumpers on pins 5 and 6 and pins 7 and 8 at the same time.
When jumpers are installed in both of these positions, the heads continuously seek back and forth across the media and the drive ignores all
control signals sent by the interface.
3.3.2 Master/slave configuration
In a two-drive system, one drive must be configured as the master and
the other as the slave. In a single-drive system, configure the drive as a
master. To configure the drive as a master or a slave, install jumpers
according to the table in Figure 6 on page 19.
Note. Do not configure an ST3491 family drive as a slave to a non-ATA-
compatible master drive.
3.3.3 No DASP– configuration
When a jumper is installed on pins 1 and 2 of the options jumper block
of the master, the master uses the PDIAG– signal from the slave to
recognize that the slave is present during startup and ready for normal
operation. Otherwise the drive uses the DASP– signal according to the
CAM ATA specification 3.2.
This configuration allows the ST3491 family drives to be compatible with
drives that do not use the PDIAG– signal.
Page 29
Master
Slave
CSEL not carried
to pin 28 of
this connector
Computer
Pin 28 grounded
at computer
ST3491 Family AT Product Manual, Rev. B 21
3.4 Cable select configuration
If your computer and both of your drives support cable select (CSEL),
you can use the cable select option to determine the master and slave.
To configure your drives to use cable select, you need to install jumpers
and to use a special cable-select cable as follows:
• Install a jumper on pins 3 and 4 of the options jumper block as shown
in Figure 6 on page 19. When a jumper is installed in this position, the
drive ignores master/slave jumpers installed on pins 7 and 8.
• You must use an interface ribbon cable built for cable-select. To make
a drive the master, attach it to the connector that has the CSEL signal
line connected to pin 28. To make a drive the slave, attach it to the
connector that has pin 28 unconnected (CSEL is not carried to pin 28
of that cable connector.) Note that CSEL is grounded at the host.
Figure 7. Connecting cable-selected drives
Page 30
22 ST3491 Family AT Product Manual, Rev. B
3.5 Drive activity LED
The drives are available with either of two activity LED options:
• An LED permanently mounted on the drive circuit board, or
• A two-pin header on the drive circuit board that accepts an LED or a
connector for a remote LED cable.
Both options are shown in Figure 6 on page 19.
If your drive has an LED mounted on its circuit board or an LED connected
by a cable to a two-pin header, the drive automatically displays its activity
on this LED.
In addition, the drive sends a drive activity signal to the LED at the front
panel of your computer using pin 39 of the I/O connector.
Page 31
ST3491 Family AT Product Manual, Rev. B 23
3.6 Supported AT commands
This section lists all ATA commands implemented in the ST3491 family
drives and describes certain commands in detail. Some commands, as
mentioned in the text, supplement the standard ATA commands. For a
complete description of all AT interface commands, refer to the
ATA Interface Reference Manual
cated, additional information is provided by the Small Form Factor
specification, SFF-8011 Rev 1.1, September 18, 1993.
The table on page 24 lists all commands implemented in the ST3491
family drives. The table uses the following abbreviations:
FR Features register
SC Sector count register
SN Sector number register
CY Cylinder register
DH Drive/head register
This register does not contain a valid parameter for this
n
command.
This register contains a valid parameter for this command. In
y
the drive/head register, both the drive and head parameters are
valid for this command.
The drive/head register contains a valid drive parameter for this
D
command. The head parameter is not valid for this command.
, part number 36111-
xxx
Seagate
. Where indi-
Page 32
24 ST3491 Family AT Product Manual, Rev. B
Command name
Active and Set Idle Timer FB n y n n D
Active Immediate F9 n n n n D
Check Idle Mode FD n y n n D
Check Power Mode 98, E5 n y n n D
Execute Drive Diagnostics 90 n n n n D
Format Track 50 n y n y y
Identify Drive EC n n n n D
Idle 97, E3 n y n n D
Idle and Set Idle Timer FA n y n n D
Idle Immediate 95, F8, E1 n n n n D
Initialize Drive Parameters 91 n y n n y
Read DMA C8, C9 — y y y y
Read Long 22, 23 n y y y y
Read Multiple C4 n y y y y
Read Sector 20, 21 n y y y y
Read Sector Buffer E4 n n n n D
Read Verify Sector 40, 41 n y y y y
Recalibrate 1X n n n n D
Seek 7X n n y y y
Set Features EF y n n n D
Set Multiple Mode C6 n y n n D
Set Sleep Mode 99, E6 n n n n D
Standby 96, E2 n n n n D
Standby Immediate 94, E0 n n n n D
Write DMA CA, CB — y y y y
Write Long 32, 33 n y y y y
Write Multiple C5 n y y y y
Write Sector 30, 31 n y y y y
Write Sector Buffer E8 n n n n D
Command
code (in hex)
Parameters used
FR SC SN CY DH
Page 33
ST3491 Family AT Product Manual, Rev. B 25
3.6.1 Identify Drive command (ECH)
The Identify Drive command transfers information about the drive to the
host following power up. The data is organized as a single 512-byte block
of data; the block’s contents are shown in the table below. All reserved
bits or words must be set to zero. Parameters listed with an “x” are
drive-specific or vary with the state of the drive.
The sector buffer parameters for ST3491 family drives are listed in the
table below. The Logical Configuration parameters shown below are for
the ST3250A. For a complete description of the Identify Drive command,
see the
36111-
Word Description Value
Seagate ATA Interface Reference Manual
xxx
.
0 Configuration information
Bit 10: 1 = disc transfer
greater than 10 Mbits/sec
Bit 6: 1 = fixed drive
Bit 4: 1 = head switch time
> 15 µsec
Bit 3: 1 = not MFM encoded
Bit 1: 1 = hard sectored disc
045A
, publication number
H
Number of fixed cylinders
(default logical emulation)
1
2 ATA reserved 0000
Number of heads (default) ST3250A: C
3
Number of unformatted
4
bytes per track
Number of unformatted
5
bytes per sector
Number of sectors per track
(default logical emulation)
6
7–9
ATA reserved (vendorunique)
continued
ST3250A: 400
ST3291A: 2F9
ST3391A: 300
ST3491A: 383
H
ST3291A: E
ST3391A: E
ST3491A: F
8D90
H
0248
H
H
H
H
H
ST3250A: 22
ST3291A: 32
ST3391A: 3E
ST3491A: 3E
0000
H
H
H
H
H
H
H
H
H
Page 34
26 ST3491 Family AT Product Manual, Rev. B
Word Description Value
Drive-unique value
expressed as ASCII
characters
10–19
Serial number: (20 ASCII
characters, 0000
= not
H
specified)
Controller type = dual-ported
20
multisector buffer with
caching
21
22
Buffer size (number of 512byte sectors)
Number of ECC bytes
available (R/W Long)
23–26 Firmware revision (8 ASCII
character string).
27–46 Drive model number (40
ASCII characters, padded to
end of string)
47 Maximum sectors per
interrupt on read/write
multiple
48 Double word I/O (not
supported)
49 DMA data transfer and
IORDY (supported)
50 ATA reserved 0000
51*
PIO data transfer cycle
timing mode
0003
H
(240D)
00F0
H
0010
(16D)
H
Drive-dependent string
Drive-dependent string:
ST3
xxxA-xx
or ST3
xxxA-xxx
0010
H
0000
H
0900
H
H
0200
H
52
Single word DMA transfer
cycle timing mode
Bit 0 = 1 indicates the fields
reported in words 54–58 are
53
valid;
Bit 1 = 1 indicates the fields
reported in words 64–8 are
valid.
54 Number of cylinders (current
emulation mode)
55 Number of heads (current
emulation mode)
0200
H
0003
H
See Section 1.
See Section 1.
Page 35
ST3491 Family AT Product Manual, Rev. B 27
Word Description Value
56 Number of sectors per track
See Section 1.
(current emulation mode)
57–58 Number of sectors (current
See Section 1.
emulation mode)
59
Current multiple sector
setting
01
xx
60–61 LBA total sectors 0000
62
63
64
Single word DMA active /
modes supported
Multiword DMA active /
modes supported
Advanced PIO modes
supported (Mode 3
0000
0103
0001
supported)
65
66
Minimum multiword DMA
transfer cycle time per word
Recommended multiword
DMA transfer cycle time per
96
H
016B
word
67
68
69 –
Minimum PIO cycle time
without IORDY flow control
Minimum PIO cycle time with
IORDY *
ATA reserved 0000
016B
00B4
127
128 –
Seagate reserved
xxxx
159
160 –
ATA reserved 0000
255
H
H
H
H
H
(150 nsec)
(363 nsec)
H
(363 nsec)
H
(180 nsec)
H
H
H
H
* Cycle times less than 363 nsec require IORDY.
Page 36
28 ST3491 Family AT Product Manual, Rev. B
3.6.2 Set Features command (EFH)
The Set Features command (command code EFH) is used by the host
to establish parameters that affect the execution of certain drive features.
To use the command: 1) write the Feature value to the Features register;
2) write the Set Features command to the command register.
Note. If the value in the Features register is not supported or is invalid,
the drive posts an Aborted Command error.
At power-on, or after a hard reset, the feature selections are restored to
the factory default values. If 66
change the feature selections (this can be canceled by setting CC
66
has not been set, a soft reset will return the settings to the factory
H
defaults.
The following table shows alterable features supported by the ST3941
family drives. Where a factory default value exists, that value is listed.
Byte Feature description
has been set, a software reset will not
H
H
). If
02
03
44
55
66
77
82
88
AA
BB
CC
Enable write cache
H
Set value for Set Transfer mode based on value in Sector
H
(factory default).
Count register.
Use maximum length of ECC (16 bytes) on read long/write
H
long commands
Disable read look-ahead feature.
H
Use current settings as default (until hard reset or power
H
(factory default).
off).
Disable ECC.
H
Disable write cache (factory default is OFF)
H
Enable ECC (
H
Enable read look-ahead feature (
H
4 bytes of ECC apply on read long/write long commands.
H
Enable reverting to power-on defaults
H
factory default
).
factory default
(factory default).
).
Page 37
ST3491 Family AT Product Manual, Rev. B 29
3.6.2.1 PIO and DMA Data Transfer Modes
The Set Features command can be used to set the type of data transfer
mechanism and transfer mode used by the drive. To do this:
1. Write Set Features command value 03
the Features register, then
2. Write a Transfer Types value to the Sector Count register. The upper
5 bits of this value define the type of data transfer, and the low order
3 bits encode the mode value. The following table identifies allowable
Transfer Types values:
Data Transfer Mechanism Transfer Types value
Mechanism name
PIO Transfer Mode
(default: Set PIO Mode 2)
PIO Transfer Mode:
Set PIO Mode 2
PIO Flow Control Transfer
Mode: Set PIO Mode = 0
PIO Flow Control Transfer
Mode: Set PIO Mode = 1
PIO Flow Control Transfer
Mode: Set PIO Mode = 2
Mode
value
H (Set Data Transfer mode) to
Data
Upper 5 bits
2 00000 000
2 00000 001
0 00001 000
1 00001 001
2 00001 010
Lower 3 bits
PIO Flow Control Transfer
Mode: Set PIO Mode = 3
Multiword DMA Mode 0 00100 000
Multiword DMA Mode 1 00100 001
Reserved
Notes:
1. If the drive does not support a commanded mode, the drive
returns an Aborted Command error.
3 00001 011
01000
continued
nnn
Page 38
30 ST3491 Family AT Product Manual, Rev. B
2. If the drive receives a Set Features command with a Mechanism and Mode value of 0000 0001 and the drive supports
disabling of IORDY, then the drive sets its default PIO transfer mode and disables IORDY.
Reserved values are intended for use in a future specification of an
alternative flow control mechanism.
3.6.3 Set Multiple Mode command (C6H)
Command code C6H enables the drive to perform Read and Write
Multiple operations and establishes the block count for these commands.
It is not required that this command is issued prior to every Read Multiple
or Write Multiple command.
The Sector Count register is loaded with the number of sectors per block.
Drives normally support block sizes of 2, 4, 8 and 16 sectors. However,
other block size values may also be supported, depending on the size of
the drive’s buffer. Upon receipt of the Set Multiple Mode command, the
drive sets BSY=1 and checks the Sector Count register.
If the Sector Count register contains a valid value and the block count is
supported, the value is loaded for all subsequent Read Multiple and Write
Multiple commands and execution of those commands is enabled. If a
block count is not supported, an Aborted Command error is posted, and
Read Multiple and Write Multiple commands are disabled.
If the Sector Count register contains 0 when the command is issued,
Read and Write Multiple commands are disabled.
At power on, or after a hardware reset, the default mode is Read and
Write Multiple disabled. If Disable Default has been set in the Features
register, then the mode remains the same as that last established prior
to a software reset, otherwise it reverts to the default of disabled.
3.6.4 Read Multiple command (C4H)
This command (code C4H) is similar to the Read Sectors command.
Interrupts are not generated on every sector, but on the transfer of a block
that contains the number of sectors defined by a Set Multiple Mode
command.
The number of sectors per block to be transferred without intervening
interrupts is programmed by the Set Multiple Mode command, which
must be executed prior to the Read Multiple command. Interrupts are
generated when DRQ is set to 1 at the beginning of each block or partial
block.
Page 39
ST3491 Family AT Product Manual, Rev. B 31
When the Read Multiple command is issued, the Sector Count register
contains the number of sectors (not the number of blocks or the block
count) requested.
If the number of requested sectors is not evenly divisible by the block
count, as many full blocks as possible are transferred, followed by a final,
partial block transfer. The partial block transfer is for
n
= remainder (sector count / block count)
If the Read Multiple command is attempted before the Set Multiple Mode
command has been executed or when Read Multiple commands are
disabled, the Read Multiple operation is rejected with an Aborted Command error.
Disc errors encountered during Read Multiple commands are posted at
the beginning of the block or partial block transfer, but DRQ is still set
and the data transfer takes place as it normally would, including transfer
of corrupted data, if any.
The contents of the Command Block registers, following the transfer of
a data block that had a sector in error, are undefined. The host should
retry the transfer as individual requests to obtain valid error information.
Subsequent blocks or partial blocks are transferred only if the error was
a correctable data error. All other errors cause the command to stop after
transfer of the block that contained the error.
n
sectors, where
3.6.5 Write Multiple command (C5H)
This command (command code C5H) is similar to the Write Sectors
command. Interrupts are not presented on each sector but on the transfer
of a block that contains the number of sectors defined by Set Multiple
Mode command.
The number of sectors per block to be transferred without intervening
interrupts is programmed by the Set Multiple Mode command, which
must be executed prior to the Write Multiple command.
When the Write Multiple command is issued, the Sector Count register
contains the number of sectors (not the number of blocks or the block
count) requested.
If the number of requested sectors is not evenly divisible by the block
count, as many full blocks as possible are transferred, followed by a final,
partial block transfer. The partial block transfer is for
n
= remainder (sector count / block count)
n
sectors, where
Page 40
32 ST3491 Family AT Product Manual, Rev. B
If the Write Multiple command is attempted before the Set Multiple Mode
command has been executed or when Write Multiple commands are
disabled, the Write Multiple operation is rejected with an aborted command error.
Disc errors encountered during Write Multiple commands are posted
after the attempted disc write of the block or partial block transferred. The
Write command ends with the sector in error, even if it was in the middle
of a block. Subsequent blocks are not transferred in the event of an error.
Interrupts are generated when DRQ is set to 1 at the beginning of each
block or partial block.
The contents of the Command Block registers following the transfer of a
data block that had a sector in error are undefined. The host should retry
the transfer as individual requests to obtain valid error information.
3.7 Onboard drive diagnostics
During startup, the drive executes a series of diagnostic tests. If the
diagnostic tests detect an error, the drive LED indicates the nature of the
error by emitting a flash code. A subset of the error flash codes are
contained in the following table.
Number of
flashes
Irregular flashes Microprocessor error
2 ROM checksum error
3 External RAM error
4 I/O chip error
5 Buffer RAM error
Error code description
3.8 ECC performance tests
The drive does not report ECC errors when it performs on-the-fly error
correction. This allows the drive to correct the data without sacrificing
performance.
Some older drive diagnostic utilities test the drive’s ability to apply ECC
by creating small data errors and then checking to see if these errors are
reported. If you run one of these tests on a drive that is functioning
properly, the test may report that the drive is failing to detect ECC errors.
However, this does not mean that the drive is malfunctioning.
Page 41
ST3491 Family AT Product Manual, Rev. B 33
3.9 Supported BIOS
The drive uses 16 bytes of ECC with Read Long and Write Long
commands. If the computer BIOS expects 7 ECC bytes, some drive
diagnostics may return false failures (typically time-out errors). If so, you
must reconfigure the computer to receive 4 bytes of ECC.
The BIOS revisions listed in the following table are fully compatible with
the AT interface implemented on the ST3491 family drives. Earlier BIOS
revisions than those listed may not fully support the AT interface as
implemented on these drives.
BIOS manufacturer Version supported
American Megatrends Dated 4/9/90 or later
Award 3.04 or higher
Quadtel Single drive, any version
Dual drive, 3.04 or higher
Phoenix ROM BIOS Plus 286, 3.10 or higher
ROM BIOS Plus 386, 1.10 or higher
PhoenixBIOS 1.00 or higher
Page 42
Page 43
Page 44
Seagate Technology, Inc.
920 Disc Drive, Scotts Valley, California 95066, USA
Publication Number: 36254-004, Rev. B Printed in USA
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