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ATA is the abbreviated form of Advanced Technology Attachment. It refers to the standard for connecting hard drives and storage devices to the system's motherboard. It is also referred to as IDE. ATA has replaced earlier technologies such as MFM, ESDI and RLL. Over the years ATA standard has improved to include higher speeds and every new standard developed by ATA has a number attributed to it that sets it apart from its previous standard.
The initial interface makes use of transistor-transistor logic (TTL) bus interface, which uses the industry standard architecture (ISA) bus protocol. The key feature about the ISA protocol is that has an asynchronous method of data transfer, so only one data or command can be send at a time.
ATA 133 standard, also referred to as the ATA 7 standard, is a disk drive standard which is defined by a speed of 133 Mbs. The ATA standard uses DMA technique to free additional processor time to allow peripherals to access the system's RAM. Though its release was under considerable debate, it turned into the preferred standard for serial link implementation in system hardware. An advanced form of ATA 133 is Ultra ATA.
The later ATA standards incorporate serial data transfer and do not have any parallel data transfer schemes. The interesting feature about serial ATA is that it makes use of 4-wire cables and is preferred when data has to be transferred at faster speeds.
Newer standards changed from a parallel data transfer scheme to serial data transfer. Serial ATA (SATA) uses narrower 4-wire cables and is a preferred interface with faster data transfer speeds. ATA-7 introduced SATA, while ATA-8 is designated for use with hybrid drives that feature internal flash memory cache. An advanced form of ATA is the Ultra ATA, which combines technology with newer Packet interface to offer higher transmission speeds and faster communication.
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Floppy Disk Drive Controller
A floppy disk controller (FDC) is a special-purpose chip and coupled circuitry that directs and controls reading from and writing to a computer's floppy disk drive (FDD).
A single FDC board can carry up to four floppy disk drives. The FDC is linked to the system bus of the computer and appears as a set of I/O ports to the CPU. It is also connected to a channel of the DMA controller. The FDC usually performs data transmission in DMA mode.
Usually an FDC communicates with the CPU via an Industry Standard Architecture (ISA) bus but an optional arrangement which is more usual in recent designs has the FDC included in a super I/O chip which communicates via a Low Pin Count bus.
Most of the FDC functions are performed by the FDC IC but some are performed by external hardware circuits.
FDC IC Functions
- Generating MFM format for the data to be recorded
- Decoding and executing commands such as seek, read, format etc
- Error detection by CRC generation / checking
- Data synchronization
External hardware functions
- Selection of FDD
- Switching-on motor in the FDD
- Resetting the FDC IC
- Enabling / disabling interrupt and DMA signals of the FDC IC
- Data separation logic
- Write pre-compensation logic
- Line drivers for signals to the FDD
- Line receivers for signals from the FDD
Input / Output ports
The FDC has three I/O ports. These are:
- Data port
- Main status register (MSR)
- Control port
The first two reside inside the FDC IC while the Control port is in the external hardware.
Data port
This port is used by the software for three different purposes:
- While issuing a command to the FDC IC, command and command parameter bytes are issued to the FDC IC through this port.
Main Status Register (MSR)
This port is used by the software to read the overall status information regarding the FDC IC and the FDD's.
Digital Control Port
This port is used by the software to control certain FDD and FDC IC functions.
About the Author
This article written by Tiel.
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