Computer - Memory Size Summary table

IEC Standard
bit	bit	0 or 1
byte	B	8 bits
kibibit	Kibit	1024 bits
kilobit	kbit	1000 bits
kibibyte (binary)	KiB	1024 bytes
kilobyte (decimal)	kB	1000 bytes
megabit	Mbit	1000 kilobits
mebibyte (binary)	MiB	1024 kibibytes
megabyte (decimal)	MB	1000 kilobytes
gigabit	Gbit	1000 megabits
gibibyte (binary)	GiB	1024 mebibytes
gigabyte (decimal)	GB	1000 megabytes
terabit	Tbit	1000 gigabits
tebibyte (binary)	TiB	1024 gibibytes
terabyte (decimal)	TB	1000 gigabytes
petabit	Pbit	1000 terabits
pebibyte (binary)	PiB	1024 tebibytes
petabyte (decimal)	PB	1000 terabytes
exabit	Ebit	1000 petabits
exbibyte (binary)	EiB	1024 pebibytes
exabyte (decimal)	EB	1000 petabytes

Computer - DAT Tapes

DAT (Digital Audio Tape)

Is a standard medium and technology for the digital recording of audio on tape at a professional level of quality. A DAT drive is a digital tape recorder with rotating heads similar to those found in a video deck. Most DAT drives can record at sample rates of 44.1 kHz, the CD audio standard, and 48 kHz. DAT has become the standard archiving technology in professional and semi-professional recording environments for master recordings. Digital inputs and outputs on professional DAT decks allow the user to transfer recordings from the DAT tape to an audio workstation for precise editing. The compact size and low cost of the DAT medium makes it an excellent way to compile the recordings that are going to be used to create a CD master.

As an archiving medium, DAT is an alternative to consider along with:

Digital Data Storage (DDS1 through DDS3)

Optical disc

VHS tape

DAT Tape

Acronym for digital audiotape, a type of magnetic tape that uses a scheme called helical scan to record data. A DAT cartridge is slightly larger than a credit card in width and height and contains a magnetic tape that can hold from 2 to 24 gigabytes of data. It can support data transfer rates of about 2 MBps. Like other types of tapes, DATs are sequential-access media.

Computer - CD's and DVD's

CD Recordable

(PMD CDR 80, Sony CDQ 80):  Blank CDR with capacity of 700mb.  Once written to, the information cannot be deleted or re-written.  Information can be written at 52x normal speed – i.e. if you are recording a 3 minute song, it will record to CD in about 3.5 seconds.

CDR Recordable Rewritable

(Sony CDQ-RW74, Sony CDQ-RW 80):  If information needs to be deleted or re-written, the customer should use a CDR-W (rewritable).  Because of the re-writing process, information transfer is slower, therefore can only be written at 4x normal speed.

DVD Recordable

Due to the proliferation of DVD and the availability of DVD drives / recorders, there are now several slightly differing formats of blank DVD media on the market.  If a customer is in any doubt as to the product they require for their hardware, they should visit the following URL’s: -

www.verbatim-europe.com      www.eu.maxell.com

DVD-R

This is the most common format of DVD media that we sell.  It is designed for virtually all PC and Mac based systems.  It is a record-once format (like CDR) with a capacity of 4.7GB per disk.  Information can be written at 4x normal speed (i.e. a 1 hour piece will write in approximately 15 minutes)

DVD-RW:

Specification as above, but re-writable.  Please note that not all PC / Mac based systems will accept re-writable media, so it is important for the customer to check compatibility at the above links.  Due to re-writing, transfer is 2.4x normal speed.

DVD+R:

This product is designed for stand-alone DVD drives mainly for the consumer / home market.  The 2 most common drive manufacturers for this media are Philips and Sony, although others are available.  Data storage capacity is 4.7GB, which equates to approximately 2 hours of video footage.  Some drives are able to compress data to allow up to 4 hours of recording.

DVD+RW:

Specification as above (DVD+R), but re-writable.

Computer Information - kb, KB, Mb, GB

Abbreviations like Kb, KB, Mb and GB

Are often confused, misunderstood or used incorrectly. Here's a brief explanation of proper usage.

Let's start at the beginning. The only data that a computer can understand is on and off. But those two simple commands can be grouped into millions of combinations and it is the way they are grouped in series that creates complex data.

The basic unit is called a bit (binary digit). Each bit has an electronic switch, or gate. If the gate is open the bit is on and electricity can go through. The computer reads on or open switches as a number 1. If the gate is closed or off, the electricity is blocked and the computer reads off bits as 0.

Bits can be grouped together to allow more complex code. Eight bits are grouped together to form a byte. This allows 256 possible combinations of 1/0. The abbreviation for bit is a lowercase "b"; the abbreviation for byte is an uppercase "B". Bits and bytes can then be expressed in larger measurements. They are generally expressed in exponents of two, known as binary code.

The Standards

Although computer data is normally measured in binary code, the prefixes for the multiples are based on the metric system. The nearest binary number to 1,000 is 2^10 or 1,024; thus 1,024 bytes was named a Kilobyte. So, although a metric "kilo" equals 1,000 (e.g. one kilogram = 1,000 grams), a binary "Kilo" equals 1,024 (e.g. one Kilobyte = 1,024 bytes). Not surprisingly, this has led to a great deal of confusion.

In December 1998, the International Electrotechnical Commission (IEC) approved a new IEC International Standard. Instead of using the metric prefixes for multiples in binary code, the new IEC standard invented specific prefixes for binary multiples made up of only the first two letters of the metric prefixes and adding the first two letters of the word "binary". Thus, for instance, instead of Kilobyte (KB) or Gigabyte (GB), the new terms would be kibibyte (KiB) or gibibyte (GiB).