Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Reexamination Certificate
1998-05-04
2001-11-20
Hudspeth, David (Department: 2753)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
C360S041000, C360S077080
Reexamination Certificate
active
06320711
ABSTRACT:
FIELD OF THE INVENTION
The invention is related to the field of disk drive systems, and in particular, to a high-speed interface that transfers user data and other data between a read channel integrated circuit and another integrated circuit.
PROBLEM
A magnetic disk system stores user data in data tracks on the surface of a disk device. The user data is transferred between the disk and the user as follows. A head is positioned over a circular data track and reads the user data as the disk spins. The head transfers the user data to a pre-amp, and the pre-amp transfers the user data to a read channel integrated circuit. The read channel integrated circuit processes and transfers the user data to a drive manager integrated circuit over a high-speed bus, such as a Non-Return to Zero (NRZ) bus. The drive manager integrated circuit transfers the user data to the user.
The magnetic disk system also stores servo position data in servo sectors on the surface of the disk device. The servo sectors are interspersed along the circular data tracks so that the head periodically encounters the servo sectors as the disk spins. When the heads are positioned over a servo sector, they transfer servo data and not user data. When the heads are positioned over a data sector with user data, they transfer user data and not servo data.
A servo system uses the servo position data to position a read/write head over a data track that contains the desired user data. One form of servo position data is coarse-resolution data that identifies the data track that is under the head. Coarse-resolution data has a resolution of plus or minus one track and does not have the resolution to center the head over the data track. The other form of servo position data is high-resolution data that indicates how far off-center a head is relative to the data track. The servo system uses the coarse-resolution data to position a head near the proper data track and uses the high-resolution data to center the head over the center of that track. The servo system must have the servo position data to effectively store or retrieve user data.
Servo position data is transferred from the disk to the servo system as follows. A read/write head reads the servo position data from the disk device. The read/write head transfers the servo position data through a pre-amp to a read channel integrated circuit. The read channel integrated circuit processes the servo position data and transfers the processed data to a drive manager integrated circuit. A processor in the drive manager integrated circuit uses the servo position data to direct the servo system to position the head.
One prior system for transferring servo position data from the disk to the processor uses dedicated analog connections to transfer the high-resolution data from the read channel integrated circuit to the drive control integrated circuit. The analog lines require dedicated pins on each integrated circuit that increase the cost of the integrated circuits, and the corresponding cost of the disk drive systems that incorporate the integrated circuits. The course-resolution data is transferred from the read channel integrated circuit to the drive control integrated circuit by lines that transmit a representation of the data pulses in the coarse-resolution servo data field. These lines are sometimes referred to as pulse/polarity lines.
Another prior system for transferring servo position data from the disk to the processor uses the read channel integrated circuit to convert the high-resolution data from analog to digital. This prior system then transfers the high-resolution data over a serial interface between the read channel integrated circuit and the drive control integrated circuit. Although, the course-resolution data is still transferred by the pulse/polarity lines, it could be decoded in the read channel integrated circuit and transferred to the drive control integrated circuit over the serial interface. The serial interface can be slow given the typical baud rate and the increase in the amount of servo position data. Unfortunately, the slow speed of the serial interface may limit the accurate positioning of the head to read or write data. The slow speed of the serial interface also limits the ability of the servo system to follow high-density data tracks that increase drive capacity. In addition, it is undesirable to transfer data over the serial interface while data is being read due to signal to noise issues.
Prior systems also use the serial interface to transfer control information between the drive manager integrated circuit and the read channel integrated circuit. The processor in the drive manager integrated circuit transfers control information to configuration registers in the read channel integrated circuit. The control information contains settings that control the operation of the read channel integrated circuit. The control information can also request information such as the course-resolution data, high-resolution data, performance information, status and mode information. If the control information could be transferred through another means, the serial bus could be eliminated to eliminate pins and save cost.
At present, there is a need for a more efficient system to transfer servo position data from the read channel integrated circuit to the drive manager integrated circuit. Such a system should transfer the servo position data at high speeds and should eliminate the analog pins on the integrated circuits. There is also a need for an alternative means to transfer control information from the drive manager integrated circuit to the read channel integrated circuit.
SOLUTION
The invention overcomes the above problems by providing a high-speed interface that exchanges user data and other data between the read channel integrated circuit and another integrated circuit, such as the drive manager integrated circuit. The high-speed interface eliminates the need for analog pins on the integrated circuits to transfer high-resolution servo position data, and thus lowers the cost of the system. The high-speed interface eliminates the need to use the serial interface to transfer servo position data, and thus speeds up the data transfer. The high-speed interface eliminates the need to use the serial interface to transfer read channel control information, and thus the serial interface could be eliminated to save cost.
The invention includes methods, systems, and integrated circuits for transferring user data and other data in a disk drive system. A read channel integrated circuit exchanges the user data with a data bus when the disk drive system is reading or writing the user data. The read channel integrated circuit exchanges the other data with the data bus when the disk drive system is reading servo data. The other integrated circuit exchanges the user data with the data bus when the disk drive system is reading or writing the user data. The other integrated circuit exchanges the other data with the data bus when the disk drive system is reading the servo data. The data bus transfers the user data and the other data between the integrated circuits. One example of the other integrated circuit is a drive manager integrated circuit. One example of the data bus is a Non-Return to Zero (NRZ) bus. Examples of the other data include read channel integrated circuit settings, read channel integrated circuit performance data, servo data, high-resolution servo data, and coarse-resolution servo data.
The read channel integrated circuit is able to exchange the other data with the data bus when the head is positioned over a servo sector because no user data is being transferred over the data bus during this period. Using the same high-speed data bus that transfers user data to also transfer other data represents a distinct advance in the art. Use of the high-speed bus to transfer the other data at high speed increases system performance and data transfer capacity while minimizing pin count.
REFERENCES:
patent: 5027233 (1991-06-01), Berti et al.
patent: 5341249 (1994-08-01), Abbott
Hudspeth David
Jorgenson Lisa K.
Kubida William J.
Neal Regina Y.
STMicroelectronics N.V.
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