Tag Archives: FireWire

Media Recognition Guide – Flash Media

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Flash memory is the alternative to byte-programmable memory, which is used by hard, floppy and Zip disks. It is much less expensive, meaning large capacity devices are economically viable and has faster access times and much better shock resistance and durability. Altogether this makes it particularly suitable for use as a portable storage device. Flash memory does have a finite number of write-erase cycles, but manufacturers can guarantee at least 100,000 cycles, which is a much larger number than with byte-programmable memory.

USB Flash Drive

Type:

Flash memory data storage device with USB interface

Introduced:

2000, though the company that invented the device is a legal issue.

Active:

Yes

Cessation:

–

Capacity:

First drive had a capacity of 8 MB but the latest versions can have capacities as large as 256 GB

Compatibility:

Widely supported by modern operating systems including Windows, Mac OS, Linux and Unix systems.

Users:

Broad. Has replaced 3.5” floppy disks as the preferred device for individuals and small organisations for personal data storage, transfer and backup.

File Systems:

FAT, NTFS, HFS+, ext2, ext3

Common manufacturers:

Many manufacturers and brands including Sandisk, Integral, HP, Kingston Technology and Sony

Recognition

USB flash drives can come in a range of shapes and sizes, but as a general rule they measure somewhere in the region of 70mm x 20mm x 10mm and all have a male USB connector at one end. Capacity also varies widely, though the majority of manufacturers specify this either by printing the information on the casing or etching it onto the connector.

Using the word ‘drive’ is misleading as nothing moves mechanically in a USB flash drive. However, they are read and written to by computers in the same way they read and write to disk drives, therefore they are referred to by operating systems as ‘drives’.

The only visible component is the male USB connector, often with a protective cap. Inside the plastic casing is a USB mass storage controller, a NAND flash memory chip and a crystal oscillator to control data output. Some drives also include jumpers and LEDS and a few also have a write-protect switch.

 

High Level Formatting

USB drives use many of the same file systems as hard disk drives, though it is rare to find a drive that contains a version that pre-dates its creation. Therefore, USB drives most likely contain FAT32, rather than FAT16 or FAT12. FAT32 is the file system most commonly found on USB drives due to its broad compatibility with all major operating systems. NTFS can be used but it is not as reliable when used on operating systems other than Windows. If a drives is intended for a specific operating system, you can expect to find either HFS+ (for Macs) or ext2 or ext3 (for Linux).

Formatting a disk is done in the same way as formatting a floppy disk. If being done on a Windows operating system for example the only difference is you will right click on the USB drive icon, rather than the floppy drive.

FireWire Flash Drive

 

Type:

Flash memory data storage device with firewire interface

Introduced:

2004

Active:

Yes

Cessation:

–

Capacity:

Either 4, 8 or 16 GB

Compatibility:

Compatible with any computer with a firewire connector

Users:

Limited. Never achieved the same popularity as USB flash drives. They come in smaller sizes and have slower memory

File Systems:

FAT, NTFS, HFS+, ext2, ext3

Common manufacturers:

Kanguru

 

Recognition

FireWire flash drives look similar and are similar in construction to USB drives, the one difference being that they use a FireWire connector, rather than a USB one. Due to this they have different data transfer rates and capacities than USB drives. Depending on which version of FireWire the drive has been manufactured with it has a transfer rate of either 49.13, 98.25 or 393 MB/s. With the exception of 40.13 MB/s, these rates exceed that of the latest USB version, however they have a much smaller capacity. Furthermore they are heavier and more expensive and fewer computers have the appropriate FireWire connectors compared to those with USB ports. Thus, FireWire flash drives have never dominated the market and are fairly rare.

High Level Formatting

FireWire drives only differ from USB drives in their type of connector, therefore they will contain the same file systems and can be formatted in the same way.

-Victoria Sloyan

Media Recognition – Hard Disk Drive part 3

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Serial Attached SCSI (SAS) Interface

Type:

Magnetic storage media

Introduced:

2004

Active:

Yes [2010]

Cessation:

–

Capacity:

Varies, but majority do not exceed 300GB

Compatibility:

Compatible with all operating systems, though drives with a capacity of 137GB or more are only compatible with Windows 98 onwards and Mac OS 10.2 onwards. Not found on 8” or 5.25” drives.

Users:

Servers and high-end computers

File Systems:

FAT, NTFS, HFS/+, ext

Common manufacturers:

Western Digital, Seagate, Toshiba, Hitachi, Samsung

Recognition

SAS was born out of SCSI developments and entered the market in 2004. One feature making it preferable to SCSI is its higher transfer rate. Its fast speeds and high level performance make it suitable for high-end personal computer hard drives and servers. The first version was slower than the latest version of SCSI having a data transfer rate of 300 MB/s. However, in 2009 this rate increased to 600 MB/s and it is expected to reach 1200 MB/s by 2012. SAS uses point-to-point topology to connect the interface and can support multiple devices (up to 200), making it popular with servers. For the same reasons SAS hard disk drives are relatively expensive therefore they are not as common on standard personal computers as the more general purpose SATA interface.

The SAS connector is a 29-position connector. It is much smaller than its predecessor, SCSI, so as to be used on 2.5” drives. SAS connectors look similar to SATA connectors. The difference is that with the SATA interface the data and power connectors lie next to each other, but are separate, whereas with SAS the two form one connector, with a piece of plastic used to keep them distinct. This similarity is deliberate so that SAS connectors are compatible with SATA drives, but not the other way around.

 

External Hard Disk Drives

 

Early Apple Macintosh computers used external SCSI hard disk drives, despite internal hard disk drives being the standard for other PCs. More recently external hard drives are primarily used as additional storage devices.

Although the early Apple external drives were only compatible with Mac OS, later drives have been manufactured to support all modern operating systems. However, they cannot support any Windows OS preceding Windows 2000, Mac OS before version 8.5.1 or the Linux OS with a kernel earlier than version 2.4 unless updates are installed.

The hard disk in an external hard disk drive is no different to that in an internal drive, though an external drive is encased in plastic and the only visible part is the connector. This can either be a SCSI, eSATA, USB or FireWire connector.

FireWire (IEEE 1394): First released in 1995 this was originally developed as a replacement for the SCSI connector and many computers since 2003 have a built-in FireWire port, particularly Apple machines. FireWire has a higher transfer rate than USB and the latest version, FireWire 3200 has a rate of 393 MB/s, which also exceeds that of eSATA, although this rate varies with Windows OS. However it is more expensive than USB, hence it has never superseded USB’s popularity. It is compatible with Windows OS from Windows XP onwards, though issues with Vista have been raised. It is also compatible with Linux OS and Mac OS from version 8.6 onwards. The FireWire cables carry power and data on a single cable, therefore only one is needed for a device.

There have been several versions of FireWire each using different connectors. Here is a brief table setting this out:

Version Cable Used Date Introduced

FireWire 400 (IEEE 1394)

6-circuit

1995

FireWire 400 (IEEE 1394a)

4-circuit

2000

FireWire 800 (IEEE 1394b)

9-circuit

2002

FireWire S3200

9-circuit

2007

It is most common to find 6-cicuit connectors on desktop computers and 4-cicuit connectors on laptops. However, in 2000 amendments were made and the 4-cicuit connector was standardised resulting in more of these connectors being found on desktop computers.

FireWire 800 and 3200 are backwards compatible with these ports, but are manufactured with a 9-cicuit connector. Adaptors are available so that 9-circuit cables can be used with 4- and 6-circuit connectors on computers.

USB (Universal Serial Bus): USB was introduced in 1996 and has since become the dominant means to connect computer peripherals to the host controller. The original USB 1.0 has a transfer rate of 12 Mbits/s, which was increased to 60 MB/s (480 Mbits/s) by USB 2.0. This was released in 2000 and standardised in 2001. Like FireWire, USB connectors carry power as well as data, therefore do not require additional power cables.

There are several different USB cables available for different uses. The most common type found on computers is the A plug and port. A second type is similar in size and is usually found on extension cables. Mini plugs are also available for use with small devices such as cameras. The other sort is squarer and about half the width of the A plug. This is known as a B plug and is used on devices that use removable cables such as printers. Having two types of connector (A and B) prevents users accidentally creating an electrical loop.

eSATA: This is SATA’s own external connector introduced in 2004 with a transfer rate of 131 MB/s. Despite having a much larger data transfer rate, few computers have eSATA ports, favouring instead USB and FireWire.

-Victoria Sloyan