What is SATA and PATA in computer?

Table of Contents

What is SATA?

SATA stands for Serial Advanced Technology Attachment. It is a standard interface used to connect storage devices like hard disk drives, solid state drives and optical drives to a computer’s motherboard.

SATA was designed to replace the older PATA (Parallel ATA) interface, offering faster data transfer speeds and other advantages. The SATA interface uses serial signaling technology, where data is transferred one bit at a time sequentially over a cable. In contrast, PATA uses parallel signaling, where multiple bits are transferred simultaneously over a cable.

Some key advantages of SATA over PATA:

Faster transfer speeds – SATA has much higher maximum bandwidth than PATA. SATA revisions can reach speeds up to 16 Gbit/s, while the fastest PATA supports only 133 Mbit/s.
Thinner cables – SATA cables are much thinner and more flexible than PATA cables, allowing better airflow and less clutter inside the computer case.
Hot swapping support – SATA devices can be connected and disconnected while the computer is running. This is not possible with PATA.

Native command queuing – SATA supports NCQ, which optimizes drive requests to improve performance. PATA does not have any native command queuing capabilities.

The SATA specification has gone through several revisions:

SATA 1.0 – First SATA version released in 2003, delivering 1.5 Gbit/s speeds.

SATA 2.0 – Released in 2004, doubled transfer rates to 3 Gbit/s.
SATA 3.0 – Released in 2009, increased speeds to 6 Gbit/s.
SATA 3.1 – Added support for mSATA solid state drives.

SATA 3.2 – Increased theoretical bandwidth to 16 Gbit/s with incremental improvements.

Today, SATA is the de facto standard interface for connecting storage drives in desktop PCs, laptops and servers. Almost all modern motherboards have multiple SATA ports to support connecting SSDs, HDDs and optical drives using SATA cables.

What is PATA?

PATA stands for Parallel Advanced Technology Attachment. It was the primary storage interface used to connect hard drives and optical drives to computers before the introduction of SATA.

PATA uses a parallel bus design that sends multiple bits of data simultaneously over 40 or 80 wire ribbon cables. The original PATA specification was first introduced by Western Digital in 1986 and was known as ATA-1. Over the years, it evolved through several iterations:

ATA-1 – First version of ATA introduced in 1986, supported up to 14.4 MB/s transfer speeds.
ATA-2 – Released in 1989, added support for logical block addressing.

ATA-3 – Launched in 1997, doubled maximum transfer rate to 33 MB/s.
Ultra ATA – Also called Ultra DMA, boosted speeds to 66 MB/s.
ATA/66 – Doubled Ultra DMA speeds to 133 MB/s.

Some key characteristics of PATA interface:

Parallel bus – Sends 16 bits of data simultaneously over a 40 or 80 wire ribbon cable.
Master/slave architecture – Allowed daisy chaining up to 2 devices per channel.

40-pin or 80-pin connector – Hard drives use 40-pin while optical drives use 80-pin connector.
5 volt power – PATA devices are powered by standard 5V power from the computer’s power supply.
No hot swapping – PATA drives must be connected before boot up.

While PATA was very popular for many years, it had limitations in terms of performance and scalability. The advent of high speed SATA eventually led to PATA being phased out in the 2000s. Today, PATA is obsolete and has been replaced entirely by SATA and more recently by NVMe in new computer systems. However, PATA hard drives and optical drives may still be found in some older legacy systems still in use today.

Difference between SATA and PATA

While both SATA and PATA are interfaces designed to connect storage devices to a computer’s motherboard, there are some key differences between the two standards:

Feature	SATA	PATA
Data Transfer Type	Serial	Parallel
Cable Type	Thin serial cable	Wide ribbon cable
Data Transfer Speed	Up to 16 Gbit/s	Up to 133 MB/s
Connector size	Much smaller	Larger 40-pin or 80-pin
Hot swappable	Yes	No
Power required	15-pin SATA power	5V/12V Molex

Some key differences:

SATA is serial while PATA is parallel – SATA transfers 1 bit at a time while PATA sends 16 bits simultaneously.
SATA supports much faster speeds – SATA has bandwidth up to 16 Gbit/s while the fastest PATA did 133 MB/s.
SATA cables are thin while PATA cables are wide ribbons.

SATA supports hot swapping, PATA does not.
SATA uses smaller connectors while PATA connectors are bulky.
SATA requires dedicated power cables. PATA just needs 5V/12V connections.

In summary, SATA is newer, faster, more flexible and designed for modern systems. PATA is obsolete legacy technology that has been phased out of use.

Advantages of SATA over PATA

Here are some of the key advantages SATA offers compared to the older PATA technology:

Speed – SATA is much faster with maximum bandwidth up to 16 Gbit/s compared to just 133 MB/s for PATA.

Cable size – SATA cables are thin and flexible, improving airflow and reducing clutter in the computer case.
Hot swapping – SATA devices can be connected and disconnected while the computer is running.
Native command queuing – SATA supports NCQ for optimized drive operations and performance.

Low voltage – SATA signaling uses lower voltage levels, reducing power requirements.
Point-to-point – SATA has a simple dedicated connection between device and controller.
Advanced features – SATA has support for modern features like NCQ, hot plugging, staggered spin-up and TRIM.

Scalability – SATA has headroom for faster speeds in future revisions.

In summary, SATA is better than PATA in almost every way – speed, cable management, features, scalability and more. SATA is designed to support modern high speed storage devices. This makes it the interface of choice for connecting hard drives, SSDs and optical drives in computers today.

Disadvantages of SATA compared to PATA

Although SATA has major advantages over PATA, there are some minor downsides to consider:

SATA is not natively supported in older systems – PATA has broader legacy hardware support.
SATA cables have less tolerance for improper installation – PATA cables install more easily in general.
SATA may require BIOS updates to enable AHCI or hot swapping capabilities.

Boot support is limited to a few SATA ports in some older BIOS versions.
Most SATA implementation lack native XOR support for RAID.
PATA allowed sharing of one set of DMA registers between devices.

SATA requires dedicated power connections for each device.
Maximum cable length is shorter for SATA compared to PATA.

However, these limitations only apply to older or legacy systems that lack native SATA support. In modern computers, SATA provides superior performance and connectivity for storage devices compared to outdated PATA technology. The advantages far outweigh the disadvantages overall.

Real-world transfer speed examples

Here are some examples of real-world SATA vs PATA transfer speeds:

SATA

SATA 1.5Gbps – Up to 150MB/s transfer speed

SATA 3.0Gbps – Up to 300MB/s transfer speed
SATA 6.0Gbps – Up to 600MB/s transfer speed
A typical SATA III SSD – Up to 550MB/s sequential read/write

A 7200 RPM SATA HDD – Up to 120MB/s sustained transfer rate

PATA

PATA66 – Up to 66MB/s transfer speed

Ultra ATA/133 – Up to 133MB/s transfer speed
A 7200 RPM PATA HDD – Up to 60MB/s transfer rate

As you can see, even a first generation SATA 1.5Gbps connection provides nearly double the bandwidth of the fastest PATA/133 interface. And the latest SATA 6Gbps has 4-5 times higher throughput than PATA.

This allows SATA hard drives and SSDs to achieve much faster real-world transfer speeds compared to what was possible with PATA devices. The speed advantage is one of the main reasons SATA has fully replaced PATA in modern computers.

SATA vs PATA compatibility

When it comes to compatibility, SATA and PATA devices generally cannot be mixed and matched:

A SATA device like an SSD or hard drive cannot be connected directly to a PATA port on older motherboards.

PATA drives cannot be connected to SATA ports on modern motherboards.

There are a few exceptions – some motherboards support PATA devices through a SATA port using a bridging chip. And there are adapters available that can allow connecting a SATA device to a legacy PATA interface. But generally speaking, SATA and PATA devices cannot be swapped between the two interfaces.

The physical connectors are different – SATA uses much smaller 7-pin data connectors while PATA requires bulky 40-pin or 80-pin connectors. The signaling and protocols are also incompatible between SATA and PATA devices.

When upgrading an older system that only supports PATA, the motherboard itself may need to be upgraded to add SATA ports. Adapters can work in some situations to allow backwards compatibility, but have limitations on performance and reliability. Overall, it’s recommended to use native SATA ports with SATA devices for best compatibility.

Typical uses of SATA and PATA

Here are some of the typical uses of SATA and PATA connections in computer systems:

SATA is commonly used to connect:

Hard disk drives (HDDs)
Solid state drives (SSDs)
Optical drives like DVD/Blu-Ray drives

RAID controllers/HBA cards

PATA was commonly used to connect:

Older hard drives before SATA became popular

Optical drives like CD-ROM and DVD-ROM
Zip drives for removable storage
Tape drives for backup

Legacy peripherals and adapters

In today’s computers, SATA is used for almost all internal storage drive connections – HDDs, SSDs and optical drives. Most modern motherboards have multiple SATA ports. Some higher end boards may also have one or two legacy PATA connectors for backwards compatibility.

Externally, eSATA connectors are a variant of SATA used for external hard drives and SSDs. USB has replaced PATA interfaces for external optical drives and other peripherals. But some older external enclosures may still use PATA to HDD/SSD connections internally.

Overall, SATA has fully replaced PATA for modern internal storage drive connections. And USB is now the standard for external devices.

SATA vs M.2 NVMe

M.2 NVMe is a high performance storage interface that is gaining popularity to replace SATA in newer systems:

NVMe stands for Non-Volatile Memory Express, a protocol designed for SSDs.

M.2 is the form factor, offering a small card-like connector vs SATA cables.
NVMe/M.2 SSDs connect directly over PCIe bus, supporting much higher speeds.
Peak bandwidth up to 4 GB/s with PCIe 4.0, vs 0.6 GB/s max for SATA.

Lower latency and higher IOPS (input/output operations per second).

However, NVMe has downsides too:

More expensive – NVMe SSDs cost considerably more per GB than SATA SSDs.

Heat output – NVMe drives run hotter and need cooling focus.
Boot support – Older systems may not have NVMe boot capability.

For typical consumer use, SATA SSDs provide adequate performance at much lower costs. But for professional workloads like video production, NVMe speeds are highly desirable. NVMe is the future high performance standard, but SATA SSDs will continue to be used in many PCs and laptops due to cost efficiency.

Conclusion

In summary:

SATA is newer, faster serial interface that replaced PATA for connecting storage drives.
SATA offers major advantages like speed, features, cable management and scalability over obsolete PATA.

NVMe/M.2 is emerging as an ultra fast successor to SATA in high end systems.
But SATA remains the most widely used internal storage drive interface in PCs and laptops.
PATA is now a legacy technology no longer used in modern computers.

So in today’s systems, you will generally find SATA ports and connectors being used for internal hard drives, solid state drives and optical disc drives. And for the foreseeable future, SATA will continue to be the de facto standard for connecting storage devices internally in the vast majority of computers, even as NVMe carves out a niche in high performance use cases. PATA, on the other hand, is firmly outdated legacy technology that has been replaced entirely by SATA in modern computing.