peripheral storage devices, hard disk drives or solid-state drives, are
self-contained sub-systems capable of storing data bits on a magnetic or
solid-state medium. These devices comprise three major components: the
storage medium, the read/write sensor, and the system-on-chip (SoC).
These components together determine the achievable storage capacity,
reliability, speed, and power consumption of the drive.
storage medium in HDDs is a rigid disk, consisting of magnetic materials
coated onto a rigid substrate. Data bits are stored by suitably
creating magnetic patterns on the medium. In SSDs, the medium is a
monolithic memory chip, comprising a vast array of pre-fabricated NAND
cells whose internal state can be altered to represent data bits.
read/write sensor is a transducer which suitably records and retrieves
the signals to and from the medium. The read/write transducer in HDDs
converts electrical signals to magnetic fields, and vice versa. In SSDs,
the write transducer alters the charge state of the NAND cell based on
the data pattern to be stored; the read transducer senses the charge
state of the cell to create a readback electrical signal.
is the brains of the device, residing on the printed circuit board
(PCB) with buffer memory and motor control chips. It embeds the
all-important functions of data recovery and data transport, as well as
other blocks required to manage the data flow and the functionality of
data recovery function performs data encoding to enable reliable
retrieval of the stored data in the
presence of sensor/medium impairments
that include inter-symbol interference, electronics noise, medium and
sensor noise, nonlinear distortion, signal drop outs, and stray
interferences. It also critically determines
how efficiently the media and the read/write sensor are utilized. If
the data recovery method is sub-par, the achievable areal density and
reliability are significantly reduced. On the other hand, powerful data
recovery techniques can enable higher areal density, improved product
reliability, and higher manufacturing yields.
data transport function handles the delivery of the recovered data using
a prescribed interface protocol. Common interface protocols used in
storage devices include Serial Advanced Technology Attachment (SATA),
Serial Attached SCSI (SAS), Consumer Electronics ATA (CE-ATA), etc.
Interoperability and compliance with standards specifications of the data
transport function are key requirements. Link_A_Media Devices
offers industry-compliant building blocks for standard data transport