Tag Archives: media recoginition

Media Recognition: DV part 3

DVCAM (encoding)

Type:
Digital videotape cassette encoding
Introduced:
1996
Active:
Yes, but few new camcorders are being produced.
Cessation:
Capacity:
184 minutes (large), 40 minutes (MiniDV).
Compatibility:
DVCAM is an enhancement of the widely adopted DV format, and uses the same encoding.
Cassettes recorded in DVCAM format can be played back in DVCAM VTRs (Video Tape Recorders), newer DV VTRs (made after the introduction of DVCAM), and DVCPRO VTRs, as long as the correct settings are specified (this resamples the signal to 4:1:1). DVCAM can also be played back in compatible HDV players.
Users:
Professional / Industrial.
File Systems:
Common Manufacturers:
Sony, Ikegami.
DVCAM is Sony’s enhancement of the DV format for the professional market. DVCAM uses the same encoding as DV, although it records ‘locked’ rather than ‘unlocked’ audio. It also differs from DV as it has a track width of 15 microns and a tape speed of 28.215 mm/sec to make it more robust. Any DV cassette can contain DVCAM format video, but some are sold with DVCAM branding on them.
Recognition
DVCAM labelled cassettes come in large (125.1 x 78 x 14.6 mm) or MiniDV (66 x 48 x 12.2mm) sizes. Tape width is ¼”. Large cassettes are used in editing and recording decks, while the smaller cassettes are used in camcorders. They are marked with the DVCAM logo, usually in the upper-right hand corner.

HDV (encoding)

Type:
Digital videotape cassette encoding
Introduced:
2003
Active:
Yes, although industry experts do not expect many new HDV products.
Cessation:
Capacity:
1 hour (MiniDV), up to 4.5 hours (large)
Compatibility:
Video is recorded in the popular MPEG-2 video format. Files can be transferred to computers without loss of quality using an IEEE 1394 connection.
There are two types of HDV, HDV 720p and HDV 1080, which are not cross-compatible.
HDV can be played back in HDV VTRs. These are often able to support other formats such as DV and DVCAM.
Users:
Amateur/Professional
File Systems:
Common Manufacturers:
Format developed by JVC, Sony, Canon and Sharp.
Unlike the other DV enhancements, HDV uses MPEG-2 compression rather than DV encoding. Any DV cassette can contain HDV format video, but some are sold with HDV branding on them.
There are two different types of HDV: HDV 720p (HD1, made by JVC) and HDV 1080 (HD2, made by Sony and Canon). HDV 1080 devices are not generally compatible with HDV 720p devices. The type of HDV used is not always identified on the cassette itself, as it depends on the camcorder used rather than the cassette.
Recognition
HDV is a tape only format which can be recorded on normal DV cassettes. Some MiniDV cassettes with lower dropout rates are indicated as being for HDV, either with text or the HDV logo. These are not essential for recording HDV video.

 

-Rebecca Nielsen

Media Recognition: DV part 2

DV (encoding)

Type:
Digital videotape cassette encoding
Introduced:
1995
Active:
Yes, but tapeless formats such as MPEG-1, MPEG-2 and MPEG-4 are becoming more popular.
Cessation:
Capacity:
MiniDV cassettes can hold up to 80/120 minutes SP/LP. Medium cassette size can hold up to 3.0/4.6 hrs SP/LP. Files sizes can be up to 1GB per 4 minutes of recording.
Compatibility:
DV format is widely adopted.
Cassettes recorded in the DV format can be played back on DVCAM, DVCPRO and HDV replay devices. However, LP recordings cannot be played back in these machines.
Users:
DV is aimed at a consumer market – may also be used by ‘prosumer’ film makers.
File Systems:
Common Manufacturers:
A consortium of over 60 manufacturers including Sony, Panasonic, JVC, Canon, and Sharp.
DV has a track width of 10 microns and a tape speed of 18.81mm/sec. It can be found on any type of DV cassette, regardless of branding, although most commonly it is the format used on MiniDV cassettes.
Recognition
DV cassettes are usually found in the small size, known as MiniDV. Medium size (97.5 × 64.5 × 14.6 mm) DV cassettes are also available, although these are not as popular as MiniDV. DV cassettes are labelled with the DV logo.
DVCPRO (encoding)
Type:
Digital videotape cassette encoding
Introduced:
1995 (DVCPRO), 1997 (DVCPRO 50), 2000 (DVCPRO HD)
Active:
Yes, but few new camcorders are being produced.
Cessation:
Capacity:
126 minutes (large), 66 minutes (medium).
Compatibility:
DVCPRO is an enhancement of the widely adopted DV format, and uses the same encoding.
Cassettes recorded in DVCPRO format can be played back only in DVCPRO Video Tape Recorders (VTRs) and some DVCAM VTRs.
Users:
Professional / Industrial; designed for electronic news gathering
File Systems:
Common Manufacturers:
Panasonic, also Philips, Ikegami and Hitachi.
DVCPRO is Panasonic’s enhancement of the DV format, which is aimed at a professional market. DVCPRO uses the same encoding as DV, but it features ‘locked’ audio, and uses 4:1:1 sampling instead of 4:2:0. It has an 18 micron track width, and a tape speed of 33.82 mm/sec which makes it more robust. DVCPRO uses Metal Particle (MP) tape rather than Metal Evaporate( ME) to improve durability.

DVCPRO 50 and DVCPRO HD are further developments of DVCPRO, which use the equivalent of 2 or 4 DV codecs in parallel to increase the video data rate.

Any DV cassette can contain DVCPRO format video, but some are sold with DVCPRO branding on them.

Recognition
DVCPRO branded cassettes come in medium (97.5 × 64.5 × 14.6mm) or large (125 × 78 × 14.6mm) cassette sizes. The medium size is for use in camcorders, and the large size in editing and recording decks. DVCPRO 50 and DVCPRO HD branded cassettes are extra-large cassettes (172 x 102 x 14.6mm). Tape width is ¼”.

DVCPRO labelled cassettes have different coloured tape doors depending on their type; DVCPRO has a yellow tape door, DVCPRO50 has a blue tape door, and DVCPRO HD has a red tape door.

Images of DVCPRO cassettes are available at the Panasonic website.

-Rebecca Nielsen

Media Recognition: DV part 1

DV can be used to refer to both a digital tape format, and a codec for digital video. DV tape usually carries video encoded with the DV codec, although it can hold any type of data. The DV format was developed in the mid 1990s by a consortium of video manufacturers, including Sony, JVC and Panasonic, and quickly became the de facto standard for home video production after introduction in 1995. Videos are recorded in .dv or .dif formats, or wrapped in an AVI, QuickTime or MXF container. These can be easily transferred to a computer with no loss of data over an IEEE 1394 (Fire Wire) connection.

DV tape is ¼ inch (6.35mm) wide. DV cassettes come in four different sizes: Small, also known as MiniDV (66 x 48 x 12.2 mm), medium (97.5 × 64.5 × 14.6 mm), large (125.1 x 78 x 14.6 mm), and extra-large (172 x 102 x 14.6 mm). MiniDV is the most popular cassette size.

DV cassettes can be encoded with one of four formats; DV, DVCAM, DVCPRO, or HDV. DV is the original encoding, and is used in consumer devices. DVCPRO and DVCAM were developed by Panasonic and Sony respectively as an enhancement of DV, and are aimed at a professional market. The basic encoding algorithm is the same as with DV, but a higher track width (18 and 15 microns versus DV’s 10 micron track width) and faster tape speed means that these formats are more robust and better suited to professional users. HDV is a high-definition variant, aimed at professionals and consumers, which uses MPEG-2 compression rather than the DV format.

Depending on the recording device, any of the four DV encodings can be recorded on any size DV cassette. However, due to different recording speeds, the formats are not always backwards compatible. A cassette recorded in an enhanced format, such as HDV, DVCAM or DVCPRO, will not play back on a standard DV player. Also, as they are supported by different companies, there are some issues with playing back a DVCPRO cassette on DVCAM equipment, and vice versa.

Although all DV cassette sizes can record any format of DV, some are marketed specifically as being of a certain type; e.g. DVCAM. The guide below looks at some of the most common varieties of DV cassette that might be encountered, and the encodings that may be used with them. It is important to remember that any type of encoding may be found on any kind of cassette, depending on what system the video was recorded on.

MiniDV (cassette)

Type:
Digital videotape cassette
Introduced:
1995
Active:
Yes, but is being replaced in popularity by hard disk and flash memory recording. At the International Consumer Electronics Show 2011 no camcorders were presented which record on tape.
Cessation:
Capacity:
Up to 80 minutes SP / 120 minutes LP, depending on the tape used; 60/90 minutes SP/LP is standard. This can also depend on the encoding used (see further entries). Files sizes can be up to 1GB per 4 minutes of recording.
Compatibility:
DV file format is widely adopted. Requires Fire Wire (IEEE 1394) port for best transfer.
Users:
Consumer and ‘Prosumer’ film makers, some professionals.
File Systems:
Common Manufacturers:
A consortium of over 60 manufacturers including Sony, Panasonic, JVC, Canon, and Sharp

MiniDV refers to the size of the cassette; as noted above, it can come with any encoding. As a consumer format they generally use DV encoding. DVCAM and HDV cassettes also come in MiniDV size.

MiniDV is the most popular DV cassette, and is used for consumer and semi-professional (‘prosumer’) recordings due to its high quality.

Recognition

These cassettes are the small cassette size, measuring 66 x 48 x 12.2mm. Tape width is ¼”. They carry the MiniDV logo, as seen below:

-Rebecca Nielsen

Media recognition – Floppy Disks part 3

3 inch Disks (Mitsumi ‘Quick Disk’)


Type:
Magnetic storage media
Introduced:
?1985
Active:
Unlikely.
Cessation:
Used in the 1980s.
Capacity:
?128KB – 256KB
Compatibility:
Requires a 3” drive appropriate to the manufacturer’s specifications.
Users:
Likely to have been individual users and small organisations. Used for word-processing, music and gaming.
File Systems:
Unknown. May vary according to use. The disks were manufactured by Mitsumi and offered as OEM to resellers and used in a range of contexts including Nintendo (Famicom), various MIDI keyboards/samplers (Roland) and the Smith Corona Personal Word Processor (PWP).
Common Manufacturers:
Disks: Mitsumi appear to have made the magnetic disk (the innards), while other manufacturers made the cases. This resulted in different case shapes and labelling. For example Sharp Corona labelled the disks as DataDisk 2.8″
Drives: Mitsumi?

Recognition
The Smith Corona Personal Word Processor (PWP) variant of the disk is double sided with one side being labelled ‘A’ and the other ‘B’. Each side also had a dedicated write-protect hole, known as a ‘breakout lug’.
2.8″ Smith Corona ‘Quick Disk’
3.5″ floppy side-by-side with a 2.8″ Smith Corona ‘Quick Disk’
Nintendo Famicon disk
Some rights reserved by bochalla
High Level Formatting
Unknown. Possibly varied according to use.
3 Inch Disk Drives
Varied according to disk. The Smith Corona word processing disks are most likely to turn up in an archival collection. These were used in a Smith Corona PWP and possible models nos. include: 3,5,6, 6BL, 7, X15,X25, 40, 50LT, 55D, 60, 65D, 75D, 80, 85DLT, 100, 100C, 220, 230, 250, 270LT, 300, 350, 355, 960, 990, 2000, 2100, 3000, 3100, 5000, 5100, 7000LT, DeVille 3, DeVille 300, Mark X, Mark XXX, Mark XL LT. 

Lego mockup of a Nintendo Famicon drive

Some rights reserved by kelvin255

Useful links
http://www.cromwell-intl.com/technical/quickdisk-recovery.html
http://en.wikipedia.org/wiki/History_of_the_floppy_disk

 -Susan Thomas

Media Recognition Guide – Flash Media

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 Guide – Iomega Zip Disks

Type:

Removable disk storage

Introduced:

1994

Active:

Yes, but used by minority

Cessation:

Capacity:

Either 100, 250 or 750MB

Compatibility:

Zip drive needs to be of a matching or higher capacity than the Zip disk. Supports Windows OS, IBM OS/2, Mac OS 7.6 to 9.2, MAC OS X and some Linux OS.

Users:

Small businesses and personal users to backup files

File Systems:

NTFS, FAT, ext2, HFS/+, ADFS

Common manufacturers:

Iomega

Recognition

The Zip disk was introduced by Iomega in 1994 as a medium capacity removable storage device to rival 3.5” floppy disks. There are three versions with capacities of 100, 250 and 750 MB, which is considerably more than a 3.5” floppy disk, and Zip disks have a quicker data transfer rate: 1 MB/s compared with a HD 3.5” floppy disk’s rate of 15.6 KB/s. However, Zip disks never reached the same popularity as floppy disks and could not compete with other forms of removable storage, such as CDs which offer much larger capacities. Therefore sales declined and use is limited at the time of writing [2010], though zip drives and disks are still available for purchase from online retailers.

Zip disks are physically similar to floppy disks, except they are larger and not quite rectangular. Their dimensions are 97 x 98 x 6mm compared to 3.5” floppy disk dimensions of 90 x 94 x 3mm.

Zip drives are more compact than floppy drives. Dimensions vary, but are around 170 x 110 x 25mm, although drives with a SCSI interface are larger, measuring 193 x 139 x 44mm. Drives are external and attached to a computer via an interface, either PATA, SCSI, USB or FireWire. Very early drives had an IDE interface (the forerunner to PATA), but these are not common. Not every interface can be found on each type of Zip drive. Below is a table setting out which interface is compatible with each drive:

Drive

Interface

PATA

SCSI

USB

FireWire

Zip 100

Yes

Yes

Yes

No

Zip 250

Yes

Yes

Yes

Yes

Zip 750

Yes

No

Yes

Yes

High Level Formatting

Zip disks use the same file systems as floppy disks, with the most common being FAT for use with Windows, HFS or HFS+ for use with Mac OS and ext2 for use with Linux. Many disks come preformatted, but can still be reformatted by the user to suit their operating system.

Formatting with Windows

This is done in the same way as formatting floppy disks: with the disk inserted in the drive open ‘My Computer’, right click over the Zip disk drive icon and select ‘Format’. There are two options; either ‘Short Format’ or ‘Long Format’ and you can change the file system used with either option by selecting either Mac or PC. Click ‘Start’ and the disk will be formatted.

Formatting with Mac OS

Insert the disk into the zip drive. Open the IomegaWare folder then open the ‘Tools’ folder and double click on the Tools icon, which will open up the window. From here click on the appropriate icon for the disk you wish to format. There are two options, either ‘Short Erase’ or ‘Long Erase’. Long Erase should be used for disks containing errors. Select ‘Erase’ to begin formatting the disk. All content will be erased and the disk will be formatted to a file system appropriate for Mac OS (HFS/+).

Formatting with Linux

Formatting a zip disk using Linux is done in the same way as formatting floppy disks, the difference being you type man zip instead of man floppy. For more details see: http://linux.die.net/man/8/floppy

-Victoria Sloyan

Media Recognition – Hard Disk Drive part 3

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

Media Recognition – Hard Disk Drives part 2

AT Attachment (ATA) Interface

Type:

Magnetic disk storage

Introduced:

1986

Active:

Only on existing computers

Cessation:

Almost completely superseded by SATA by 2007

Capacity:

750 GB

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.

Users:

Desktop and laptop computers, particularly low-end ones. The primary interface used by IBM and adopted by Apple in 1994.

File Systems:

FAT, NTFS, HFS/+, CP/M, ext, MFS

Common manufacturers:

Present: Western Digital, Seagate, Toshiba, Hitachi, Samsung

Past: IMB, Apple, Sony, Hewell-Packard, Maxtor

Recognition

ATA, designed in 1986 was an evolved form of Western Digital’s original Integrated Drive Electronics (IDE). It was used for desktop and laptop computers. After the development of SATA in 2003 ATA became retroactively known as Parallel ATA (PATA).

Here is an example of an ATA interface. It is identified as ATA because of the rectangular 40-pin connector socket used. The second image shows the male connector.

 

 

The first ATA hard disk drive was used in the Compaq Deskpro 386. It had a transfer rate of 16 MB/s and a capacity of 128 GB. Later versions had larger transfer rates, though none exceeded 80 MB/s until 2005. Before the advent of SATA, ATA hard disk drives were popular with IBM PCs due to their low cost. ATA drives are also found on post-1994 low-end Apple Microsystems, the first being the Apple Quadra 630. In 1997 Apple also adopted ATA for their high-end machines starting with the Apple Powerbook G3. The ATA connector has a relatively short cable so ATA hard disk drives are commonly inbuilt.

 

Serial ATA (SATA) Interface

Type:

Magnetic disk storage

Introduced:

2003

Active:

Yes [2010]

Cessation:

Capacity:

Up to 2TB [2010]

Compatibility:

Compatible with at least one version of all major operating systems: supports versions of Windows after XP. Also, drives with a capacity of 137GB or more are only compatible with Windows 98 onwards and Mac OS 10.2 onwards. Unlikely to be found on 8” or 5.25” drives.

Users:

Servers, desktop and laptop computers. Adopted by IBM and Apple to replace ATA.

File Systems:

FAT, NTFS, HFS/+, ext

Common manufacturers:

Present [2010]: Western Digital, Seagate, Toshiba, Hitachi, Samsung

Past: Maxtor

Recognition

SATA was introduced in 2003 as a faster version of ATA and is used with desktops, laptops and servers. It was intended to replace ATA, and had almost completely done so by 2007. SATA uses AHCI (Advanced Host Controller Interface) and if a computer does not have it SATA runs in ATA emulation mode. This applies to Windows OS up to Windows XP, though Windows Vista and later versions support AHCI. Linux with a kernel version 2.16.19 onwards will support AHCI as will Solaris operating system.

The image below shows an example of a SATA interfaced hard disk. The manufacturer’s details are clearly displayed. This type of interface uses a different connector, which is more clearly visible in the second image.

 

The SATA interface uses a 7-pin connector and socket, as seen in the above image. SATA differs from its predecessors in that it has the option of two power sockets. There is the standard Molex power socket on the right, but SATA drives also have their own power socket. This is a 15-pin connector situated next to the data socket. The image below shows the reverse side of the hard disk drive. The data socket is on the left and the power connector is on the right.

The images below show the two male connectors, with the data connector first then the power connector.

Initially SATA had a transfer rate of 131 MB/s and the SATA revision 2.0 increased this to 300 MB/s. SATA is still currently being developed and the latest version released in 2009 has a transfer rate of 600 MB/s. External SATA hard disk drives often include their own eSATA connector. More information about this will be in the next post.

Small Computer Scientific Interface (SCSI) Interface

Type:

Magnetic storage media

Introduced:

1981 (under the name SASI)

Active:

Only on existing computers

Cessation:

Early twenty-first century

Capacity:

2 TB

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.

Users:

Servers and primarily high-end computers. Used on all microcomputers until ATA established. Used by Apple for low-end machines until 1994 and high-end machines until 1999.

File Systems:

FAT, NTFS, HFS/+, CP/M, ext, MFS

Common manufacturers:

Present: Western Digital, Seagate, Toshiba, Hitachi, Samsung

Past: IMB, Apple, Sony, Hewell-Packard, Maxtor

Recognition

SCSI was introduced in 1981 under the name SASI (Shugart Associates System Interface). It was used with various operating systems including Microsoft Windows, Mac OS, Unix and Linux. However, as ATA gained popularity SCSI became associated more with high-end machines and servers. Even then SCSI began to lose popularity in the 1990s and was abandoned by Apple Macintosh in 1999. In the last decade provision for SCSI on motherboards has been largely discontinued with manufacturers preferring SATA and SAS.

The SCSI interface uses either a 68 or 80-pin connector (68-pin is more common) and a Molex power connector. The images below show the female and male 68-pin socket and connector.

 

The first SCSI interface had a transfer rate of 3.5 MB/s which soon increased to 5 MB/S. The rate increased in 1994, 1997 and again in 2003 to reach 320 MB/s.

-Victoria Sloyan

Media Recognition – Hard Disk Drives part 1

Inbuilt hard disk drives were first introduced in 1980. Most are labelled with the manufacturer’s name or logo and contain details of the disk model, though this isn’t always visible if the drive is in a casing.

There are four variables that can be used to classify a hard disk drive which are:

1. Form Factor (physical size)

2. Capacity

3. Compatibility

4. Interface – the main differentiator

Form Factors

Internal hard drives were initially sized to match floppy drive sizes and have a compatible interface.

 

 

8 inch: (241.3 x 117.5 x 164.1mm) Disk drives this size will not have a SATA or SAS interface, since 8” drives were discontinued by the time they were developed.

5.25 inch: (203 x 164.1mm x 82.8mm or 41.4mm) There are two heights available: full height (82.8mm) and half height (41.4mm). Half height is more common, but both were discontinued by the late 1990s. 5.25” drives are unlikely to have either a SATA or SAS interface, since they were not introduced until 2003 and 2004.

3.5 inch: (461 x 414 x 203mm)

2.5 inch: (69.85 x 7 x 100mm) Originally primarily used for portable machines such as laptops, though from 2008 it replaced 3.5” drives in PCs. Higher capacity drives are 12.5mm high rather than 7mm.

Smaller drives, including 1.8”, 1” and 0.85” exist and were used in portable devices like mobile phones and memory cards, but this ceased in 2009 due to the popularity of flash memory.

Capacity

 

The capacity of a hard disk drive is dependent on its form factor, year of manufacture and intended use (servers for example have much larger hard drives than those found in laptops).

Form Factor: 8” and 5.25” disk drives have smaller capacities than 3.5” and 2.5” drives because they were manufactured before the technology existed to store vast amounts of data. The table below illustrates the maximum capacities held by each form factor.

Form Factor

Maximum Capacity

Date

8”

20 GB

Full height 5.25”

47 GB

1998

Half height 5.25”

19.3 GB

1998

3.5”

2 TB

2009

2.5”

1 TB

2007

http://en.wikipedia.org/wiki/Hard_disk#Capacity_measurements

 

Be aware that these are the maximum capacities and actual drive sizes will vary widely. In part this is to suit the different budgets of consumers, but is also due to the technological abilities at the time of manufacture. For instance, 2.5” drives can reach 1 TB, but only since 2007, so no 2.5” drive manufactured before this will have a capacity this large. A brief chronology of size expansion may be useful:

1980: First hard drive disk has a capacity of 5 MB

1991: 2.5″ drive expanded to 100 MB

2005: First 500 GB drive available

2006: 750 GB drives introduced

2007: 1 TB 3.5″ and 2.5″ drives released

2009: 2 TB 3.5″ drives released

Despite 2TB and 1TB drives being available, most hard disk drives do not exceed 500GB.

 

The type and version of an interface used also has an impact on the maximum capacity. For example, the first ATA interface supports up to 137 GB, but version 6 (ATA-6) has a maximum capacity to 144PB, although disk drives don’t reach this size due to other technological limitations and the fact that it isn’t commercially viable. The SCSI interface could from the start support 2.2 TB and this increased to 9.44ZB in 2001, but again, hard disk drives are not actually manufactured in these sizes.

 

Compatibility

As a general rule all types of hard drive are compatible with the main operating systems. However, there are issues with larger capacity hard disk drives being compatible with older operating systems.

 

DOS systems generally cannot recognise drives larger than 8.4 GB and Windows 95 has a limit of 32GB. Windows 98 is restricted to 64GB, but this is not an operating system restriction, it is imposed by the Microsoft disk setup tools FDISK.EXE and FORMAT.COM.

The BIOS installed on a computer can also impact compatibility as pre-1998 BIOS cannot support drives larger than 8.4GB and pre-2002 BIOS cannot support drives larger than 137GB. However, this only affects ATA hard disk drives since the other types do not rely on BIOS for support.

 

Interface

The main difference between hard disk drives is the type of interface used. This connects the hard disk to the motherboard. The most common types are:

  • ATA (also known as IDE and PATA)
  • Serial ATA (SATA)
  • Small Computer Scientific Interface (SCSI)
  • Serial Attached SCSI (SAS)

All hard drives have two cables; one connects to the motherboard and the other to a power socket. The majority use the same power cable known as a Molex connector. There are several types, but the most common one used for hard disk drives is the Molex 8981 Series Power Connector. This has four conductors and the standard pin-out is yellow (+12 V), black (ground), black (ground) and red (+5 V).

 

 

 

-Victoria Sloyan

Media Recognition – Optical Disks part 3

DVD

 

Type:

Optical storage media

Introduced:

1995

Active:

Yes [2010]

Cessation:

Capacity:

1.4-17 GB (although 17 GB disk is very rare. Common large capacity is 9.4 GB)

Compatibility:

DVDs come in two formats: DVD- and DVD+ and neither are universally compatible with disk drives. Some DVD players will only read the same format disks, though DVD writers that only write DVD+R/RW disks will read DVD-R disks. Dual format drives are available which are compatible with both formats.

Users:

Broad. Its larger capacity means it is often favoured over CDs for large data file storage. It is also the medium of choice for watching audio visual material, having superseded VHS video cassettes.

File Systems:

UDF, ISO9660, HFS/+

Common Manufacturers:

Maxell, Philips, Sony, Verbatim, Memorex

 

Recognition

 

DVDs come in two sizes: standard 12cm and 8cm ‘mini-DVD’. As with CDs, these are often clearly marked with the manufacturer and disk type. However, unlike CDs if you put a DVD into a computer disk drive and select ‘Properties’ the window that opens will state not only that it is a DVD, but will also identify the DVD type (i.e. DVD-RW).

The capacity of a DVD varies quite widely and this is due to its construction. Similar to floppy disks, DVDs can be either single or double sided (SS or DS) and can also be single or double layered (SL or DL). This information is not recorded on a disk, but the disk capacity which is shown does suggest how the disk is constructed. The table below shows the different capacities for a standard sized CD. Be aware that DS DL disks are very rare.

Construction

Capacity

Single Sided and Single Layered (SS SL)

4.7 KB

Single Sided and Double Layered (SS DL)

8.5 KB

Double Sided and Single Layered (DS SL)

9.4 KB

Double Sided and Double Layered (DS DL) 17 KB

The capacities for miniDVDs are:

Construction

Capacity

Single Sided and Single Layered (SS SL)

1.46 KB

Single Sided and Double Layered (SS DL)

2.66 KB

Double Sided and Single Layered (DS SL)

2.92 KB

Double Sided and Double Layered (DS DL) 5.32 KB

DVDs also vary in writing speed. Original DVDs were 1x, which means they wrote 1,318 KB/s. This translates to 61 minutes for single layered DVDs and 107 minutes for dual layer. Currently DVD speeds increase by multiples of two up to 24x, with the omission of 14x. There is also 2.4x and 2.6x and speeds available depend on the DVD format. These variations affect writing speed and do not impact on any other aspect of a DVD.

Unlike compact disks, there is no single standardised recordable format for DVDs. Instead two formats are competing for the greater market share: DVD- and DVD+. There is little difference between the two in terms of manufacture and performance. The biggest issue is compatibility as not all DVD- disks work with DVD+ drives and vice versa. In July 2003 the hardware website cdrinfo.com produced a comprehensive compatibility test for the different DVD recording formats which concluded that DVD- is the most compatible (compatible with 92.21% of DVD players and drives). A full list of results, including compatibility results for individual DVD players can be found on the website http://www.cdrinfo.com/Sections/DVDMediaFormats/

DVD Formats

This table lists the different DVD formats and the years they were introduced. DL stands for Double Layer.

Format

Year Introduced

Features

DVD-R 1997 Write once media
DVD+RW 1997 Rewriteable media
DVD-RW 1999 Rewriteable media
DVD+R 2002 Write once media
DVD+R DL 2003 Write once, dual layer media
DVD-R DL 2005 Write once, dual layer media
DVD+RW DL 2006 Rewriteable, dual layer media
DVD-RW DL 2007 Rewriteable, dual layer media

High Definition DVD (HD DVD)

 

Type:

Optical storage media

Introduced:

2006

Active:

Only by existing users

Cessation:

Format abandoned in 2008

Capacity:

Standard size disk capacity ranges from 15-60 GB (although 60 GB disk is very rare. Common large capacity is 30 GB). Mini-HD DVD capacity ranges from 4.7-18.8 GB.

Compatibility:

A HD DVD player or drive is required.

Users:

Limited. Used as data storage, particularly video, but small lifespan means it did not establish a large user base.

File Systems:

UDF, ISO9660

Common Manufacturers:

Toshiba

 

Recognition

As with standard DVDs, HD DVD come in the 12cm and 8cm size and look identical to other DVDs, save for any labelling. HD DVD was indented to be the successor to standard DVDs with its increased capacity of 30GB. However, HD DVDs were in direct competition with blu-ray disks, another high density optical disk. Blu-ray proved to be the more popular choice and the HD DVD format was abandoned by creators Toshiba in 2008.

Again, like standard DVDs, an HD DVD capacity depends on its construction and DS DL HD DVDs are also rare like similar standard DVDs.

Construction

Capacity

Single Sided and Single Layered (SS SL)

15 KB

Single Sided and Double Layered (SS DL)

30 KB

Double Sided and Single Layered (DS SL)

30 KB

Double Sided and Double Layered (DS DL) 60 KB

 

The capacities for miniDVDs are:

Construction

Capacity

Single Sided and Single Layered (SS SL)

4.7 KB

Single Sided and Double Layered (SS DL)

9.4 KB

Double Sided and Single Layered (DS SL)

9.4 KB

Double Sided and Double Layered (DS DL) 18.8 KB

 

HD DVDs are only available in two speeds. The original speed writes data to the disk at a rate of 4.5 MB/s. 2x writes data at a rate of 9 MB/s.

HD DVDs are available in the –R and –RW formats, though not DVD+. These follow the Orange Book standards and the format is often stated clearly on each disk.

An HD DVD drive or player is required in order to read an HD disk. These are backwards compatible so can also read CDs and standard DVDs. HD DVD drives can be used with computers running Windows XP, Windows Vista, Mac OS 10 (version 10.5) and many varieties of Linux.

Blu-ray Disks

Type:

Optical storage media

Introduced:

2002

Active:

Yes [2010]

Cessation:

Capacity:

7.5-50 GB

Compatibility:

Blu-ray disks only work in Blu-ray disk players, which at the time of writing [2010] are inbuilt on some modern computers, but these do not dominate the market.

Users:

Mainly used for high-definition video (pre-pressed films) and video games (e.g. Playstation 3). This is still a relatively new technology and has not yet had much impact on the data storage market.

File Systems:

UDF, ISO9660

Common Manufacturers:

Sony, Mitsubishi, Philips, Hitachi, Panasonic

Recognition

Blu-ray disks look identical to CDs and DVDs and like them come in 12 and 8cm sizes, both of which come in recordable (BD-R) and rewritable (BD-RE) formats.

 

All Blu-ray disks are single sided, but like DVDs can be single or double layered, which affects the disk capacity:

 

Size

Single Layer Capacity

Dual Layer Capacity

Standard Blu-ray (12cm) 25 GB 50 GB
Mini-Blu-ray (8cm) 7.8 GB 15.6 GB

-Victoria Sloyan