Quick answer
IDE (Integrated Drive Electronics) is a type of parallel ATA hard drive interface used between the 1980s and early 2000s for connecting storage devices like hard disk drives and optical drives to a computer. IDE drives are considered a legacy technology, having been largely superseded by newer serial ATA interfaces.
IDE, short for Integrated Drive Electronics, refers to a standard interface used for connecting storage devices like hard drives and optical drives to a computer’s motherboard. Introduced in the mid-1980s, IDE became the predominant storage interface for PCs throughout the 1990s and early 2000s.
IDE is a type of parallel ATA (Advanced Technology Attachment) interface, meaning it transmits multiple bits of data in parallel, unlike newer serial ATA interfaces which transmit data sequentially one bit at a time. The “Integrated Drive Electronics” name comes from the fact that IDE moves the hard drive controller from the interface card onto the disk drive itself, allowing for simpler cabling.
At its core, an IDE interface consists of a 40- or 80-wire ribbon cable that attaches to the motherboard through a connector. Up to two IDE devices can be daisy-chained together per interface channel. Popular IDE hard drive form factors included 3.5-inch and 2.5-inch.
While extremely common in earlier eras of personal computing, IDE has largely been superseded by newer interfaces like SATA in the last 15+ years. However, understanding IDE still provides helpful insight into modern computer data storage history and terminology.
Types of IDE Interface
There are several variants of the IDE standard that have existed over time:
– ATA-1 – The original IDE interface introduced in 1986, supports up to 2 drives per channel with a maximum throughput of 8 MB/s
– ATA-2 – An improved version from 1988 that added support for logical block addressing and increased maximum throughput to 16.6 MB/s
– EIDE – “Enhanced IDE” introduced in 1989 added support for larger drive capacities, more flexible configs, and DMA modes
– ATA-3 – A minor 1996 update to accommodate faster drives up to 33 MB/s transfer rates
– ATA/33 – In 1997 raised the maximum data transfer rate to 33 MB/s
– ATA/66 – Doubled the transfer rate again to 66 MB/s in 1999
– ATA/100 – The fastest IDE spec from 2000 supporting 100 MB/s transfer speeds
– ATA/133 – A final 2003 update to the IDE standard supporting 133 MB/s
In addition to these base specs, other IDE feature sets were defined over time including:
– Fast ATA – Common 4-pin power connector for 3.5″ hard drives
– CompactFlash IDE – IDE-based precursor to CompactFlash storage standard
– ATAPI – Extension for supporting optical drives and other devices
IDE Drive Types
Many types of storage devices were designed to connect via the various IDE standards over the year. The most common IDE drive form factors included:
– 3.5″ Desktop Hard Drives – The classic bulky hard drives used in desktop PCs. Required both power and IDE connections.
– 2.5″ Laptop Hard Drives – Smaller notebook-sized drives. Some needed only an IDE interface for both power and data.
– 5.25″ Optical Drives – CD-ROM, CD-RW, DVD-ROM, etc drives. Used IDE for data and a separate power connector.
– 3.5″ Floppy Drives – Floppies used a special IDE-like interface designed for lower throughput.
– 2.5″ IDE SSDs – Early solid state drives retrofitted for the IDE interface.
– IDE Tape Drives – Used magnetic tape cartridges for backup/archiving purposes.
– Memory Cards – Some early compact flash cards were IDE-interfaced.
– Hard Drive Enclosures – Convert SATA drives to external IDE connections.
Note that while the drives themselves connected via IDE cabling, they still required a compatible IDE interface on the motherboard itself and an appropriate OS driver.
IDE Cable Types
There were a few common cable types used to connect devices to an IDE port:
– 40-wire IDE – The original cable standard supporting 2 drives on one channel.
– 80-wire high-speed IDE – An improved cable with shorter maximum length that enabled faster transfer rates.
– 40-pin IDE – Used for attaching a single IDE device to a motherboard port.
– 4-pin Molex Power – Provided +12V and +5V power to 3.5″ IDE hard drives.
– LP4 Power Connector – Small 4-pin connector for powering 2.5″ laptop IDE drives.
– SCA Connector – Alternative connector for attaching 2.5″ drives like those in laptops.
– Berg Connector – Early 5.25″ floppy drive power connector that predated the 4-pin Molex.
IDE Drive Jumpers
Most 3.5″ IDE hard drives required setting jumpers on the drive to configure parameters like:
– Master/Slave – Which drive on a shared cable to identify as.
– Cable Select – Lets the cable determine master/slave identities
– Spindle Speed – Sets rotation rate based on performance needs.
– Capacity Limiting – For older systems that couldn’t handle full drive capacity.
Jumper settings were indicated in the technical documentation for a drive and allowed custom configurations.
IDE Drive Partitions
Like modern hard drives, IDE drives were partitioned and formatted to create usable file systems:
– MBR Partitioning – The Master Boot Record partition table was standard for IDE drives. Allowed up to four primary partitions.
– FAT16/FAT32 File Systems – The FAT file systems were widely used on IDE hard drives. Supported by all major operating systems.
– NTFS File System – More advanced file system introduced in Windows NT and 2000 for better performance and security.
– EXT2/EXT3 File Systems – Common Linux file systems also widely used on IDE hard drives and SSDs.
– Other File Systems – Some other less common options included HFS (Mac OS), ext4 (Linux), CDFS (optical media).
Most IDE drives were low-level formatted at the factory and required OS-based tools to create partitions and high-level file system formats.
Master/Slave IDE Channels
IDE interfaces contained one or more channels, each with a master and slave device attached:
– Primary Channel – The first and typically only IDE channel on a system. Hosted the primary boot drive.
– Secondary Channel – A second optional channel used for additional storage devices.
– Master Drive – The primary device with priority access to the channel. Often the boot drive.
– Slave Drive – A secondary device on the same cable as master, with lower priority.
Cable select jumpers could automatically assign master/slave identities based on cable connector position.
This hierarchy helped coordinate multiple devices sharing a parallel interface. Modern serial ATA interfaces no longer use master/slave device identities.
IDE transfer modes and protocols
IDE devices and interfaces supported a variety of transfer modes and protocols:
– PIO Mode – Programmed I/O was a slower asynchronous data transfer mode.
– MWDMA Mode – Multiword DMA improved speed with buffered synchronous transfers.
– UDMA Mode – Ultra DMA introduced in 1997 was the fastest, reaching 133 MB/s burst rates.
– ATA Protocol – AT Attachment was the core protocol governing IDE commands and handshaking.
– ATAPI Protocol – Extension to ATA that added support for optical drives, tape drives and other devices.
Higher modes required support from both the drive and controller to function. Jumper settings could sometimes limit maximum modes.
Installing an IDE Drive
Installing an IDE storage device involved a physical and logical installation process:
Physical Installation
1. Mount the drive into drive bays in the computer case
2. Attach the IDE ribbon cable to the backplane on the drive
3. Connect opposite cable end to IDE port on the motherboard
4. Attach 4-pin power connector from PSU to drive (if 3.5″ drive)
5. Configure any jumpers on the drive appropriately
Logical Installation
1. Boot into BIOS setup utility and enable IDE ports/channels
2. Use FDISK or disk management utility to create partitions
3. Format partitions to create usable file systems (e.g. FAT32, NTFS)
4. Assign drive letters in OS if necessary
5. Install any required drivers for the OS to recognize drive
6. System is ready to start storing data on the IDE drive
With that complete, the IDE drive can start sending and receiving data through the parallel interface to the motherboard based on the configured transfer modes and protocols.
Advantages of IDE
IDE interfaces and drives had a number of advantages that made them the de facto standard for many years:
– High Data Throughput – IDE performance improved over time, reaching up to 133 MB/s transfer rates
– Low Cost – IDE cables, connectors and controllers were inexpensive to implement
– Simplicity – Easy configuration and installation process compared to earlier ST-506 and ESDI drives.
– Universality – IDE was supported across virtually all PC platforms and operating systems
– High Availability – Mass adoption ensured IDE drives and parts remained easy to obtain
– Large Drive Support – Later EIDE and ATA standards supported huge drives up to 2 TB+
For typical desktop use cases through the 90’s and early 2000’s, IDE provided an ideal blend of performance, capacity, affordability and ubiquity.
Disadvantages of IDE
While very successful in its time, IDE had some notable drawbacks that eventually led to its replacement:
– Limited Cable Lengths – Max cable length of 18 inches restricted physical drive locations
– Shared Bandwidth – Master and slave drives shared the maximum interface throughput
– Limited Device Count – Only 2 drives could be daisy chained per IDE channel
– Electrical Interference – Cable signaling issues could impact signal integrity at higher speeds
– Limited Hot-Swappability – Drives couldn’t easily be removed and added while powered on
– Slowerburst Transfer Speeds – IDE sustained reads/writes were much lower than maximum burst speeds
– Pin Count Limitations – The 40-pin connector imposed physical limits on performance
These limitations made it difficult for IDE to scale much beyond the ATA/133 generation.
The move from IDE to SATA
By the mid-2000s, the aging IDE technology was bumping up against both performance and configuration limits. This led to the introduction and eventual dominance of the Serial ATA (SATA) standard:
– Serial Bus – SATA uses serial signaling instead of IDE’s parallel bus, enabling much higher speeds.
– Point-to-Point – SATA has point-to-point connections instead of shared buses, improving bandwidth.
– Hot Swappability – SATA drives are removable without powering off the system.
– Thinner Cables – SATA uses thin, flexible cables instead of wide ribbons.
– Smaller Connectors – The compact SATA connectors take up less space on motherboards and drives.
– Software Configuration – SATA interfaces auto-negotiate link speed and use software for configuration.
– Higher Speeds – SATA interfaces go far beyond ATA/133, reaching speeds of 6 Gb/s and higher.
By 2005, SATA had effectively replaced IDE as the standard for both desktop and laptop PCs. Today SATA continues to be used alongside even faster interfaces like PCI Express/NVMe.
Common IDE hard drive brands and models
Many brands and specific model lines of IDE hard drives were popular over the years:
– Western Digital Caviar – Extremely common consumer IDE drive series. Known for performance and reliability.
– Seagate Barracuda – Versatile performance-focused Seagate desktop drive family.
– IBM Deskstar – IBM’s line of desktop IDE drives focused on capacity and reliability.
– Maxtor DiamondMax – Maxtor’s IDE drives offered good performance for the price.
– Quantum Fireball – Quantum’s IDE drives were featured in many OEM systems.
– Samsung SpinPoint – Samsung desktop drives balanced price and performance.
– Hitachi DeskStar – Hitachi drives were featured in many name brand PCs.
– Fujitsu – Fujitsu made reliable IDE drives even though they had limited consumer market share.
There were many other brands and models like Toshiba’s MK series. Together they dominated the PC market before SATA drives took over.
Conclusion
IDE hard drives and interfaces like ATA/133 were the dominant standard for PC data storage from the late 80’s through early 2000’s. After replacing earlier interfaces like ST-506 and ESDI, IDE delivered a good mixture of affordability, capacity, performance and ubiquity. For well over a decade, IDE was the interface of choice for desktops and laptops alike.
While extremely successful, IDE was ultimately replaced in the mid-2000’s by newer Serial ATA interfaces that could better meet the needs of faster processors, more resource-intensive applications, larger and more devices. But for a generation of computing hardware, IDE delivered exactly what was needed. Its cost and engineering trade-offs made desktop and mobile computing practical and accessible for millions of people around the world. Even today, IDE’s impact can be seen in everything from terminology to design concepts that influenced Serial ATA interfaces used in modern systems.