KarbosGuide.com. Module 5b1.

About the interfaces EIDE, Ultra DMA and AGP

The contents:

  • What is EIDE?
  • Four units controlled by the motherboard

    On the following pages:

  • The EIDE cable
  • The Promise FastTrack EIDE controller
  • Transfer speeds and protocols
  • What does Ultra DMA offer?
  • Looking at a good harddisk
  • ATA/66
  • Configuring your EIDE hard disk
  • What is AGP?
  • Next page
  • Previous page

  • What is EIDE?

    EIDE is the current standard for inexpensive, high performance hard disks used in PCs.

    EIDE stands for Enhanced IDE and it is registered name own by harddisk manufacture Western Digital. They also own the name "IDE".

    Other companies like Seagate, IBM, Quantum and Maxtor Uses the term ATA, which stands for Advanced Technology Attachment. But it is all the same. However there are many differant protocols behind the terms.

    You can think of EIDE as a bus - which is a host controller - which controls it, and you can connect up to four units. Here you see the controller and its two channels:

    All Pentium system boards since 1995 have this EIDE controller built into the chip set. That allows the hard disk and other EIDE units to be connected directly to the system board.


    The EIDE standard is a great improvement over the old IDE. Here are some examples:

  • The hard disk can exceed the 528 MB IDE limit. Currently the largest EIDE disks are of 37 GB and this number keeps increasing. IBM has promised harddisks of more than 100 GB before year 2001.

  • The hard disk's interface is moved from the ISA bus to the high speed PCI bus.

  • Four units can be connected to the system board, which has two EIDE channels. Each channel can be connected to a master and a slave unit.

    The most important feature is the interface directly on the PCI bus. This has given EIDE transfer speeds and disk capacities, which far exceed older controller principles. Concurrently, there is a continual development of the protocols, which are needed for the connection between the units and the EIDE bus.

    Four units controlled by the motherboard

    The EIDE interface is not designed for hard disks only. There are four channels, which can be connected to four independent units:

  • Hard disks
  • CD-ROM drives
  • CR-RW drives
  • DVD drives
  • LS 120, Zip or HiFD drive
  • Tape streamers

    EIDE is thus designed as an inexpensive all-round interface, which can be connected to all kinds of storage media.

    Auto detect

    The BIOS on the system board has a neat auto detect feature, which often allows EIDE units to be connected directly and work immediately. The PC start up program automatically finds the necessary information about the drive via the auto detect function.

    Sometimes you have to assist the hard disk installation by activating the auto detect in the CMOS Setup program, but often it runs by itself. You definitely do not have to key in information about cylinders, etc., as you had to with earlier IDE units.

  • Next page
  • Previous page

    To learn more

    Read more the boot process and system bus in Module 2b

    Read about file systems in module 6a

    Read about I/O buses in module 2c

    Read about the motherboard chip set in module 2d

    Read about RAM in module 2e

    Read Module 5c about SCSI, USB etc.

    Read module 7a about monitors, and 7b on graphics card.

    Click for Module 7d about digital music, MP3s

    [Main page]
    [Karbo's Dictionary]
    [The Software Guides]

    Copyright (c) 1996-2005 by Michael B. Karbo. www.karbosguide.com.