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Slinfold Computer Café

Miscellany

Why is Bluetooth so called?

The technology behind Bluetooth was created by Sven Mattisson, a former engineer at Lund Universiry in Sweden.

In 1995, he joined Ericsson Mobile Communications and, with Dutchman Jaap Haartsen, began work on creating short-range radio links with low output to allow electronic devices to communicate with each other wirelessly.

The project found an enthusiastic supporter in Intel mobile computing engineer Jim Kardach, who brought together Ericsson, Nokia, Toshiba and IBM representing 60 percent of the cellphone and portable computer markets at the time, in an open IP (intellectual property) group to develop the system.

Bluetooth technology was launched in May 1998 and is now used by billions of devices.  Devices communicate wirelessly within the unlicensed industrial, scientific and medical band at 2.4 to 2.485 GHz, using a spread spectrum, frequency hopping. full-duplex signal at a nominal rate of 1,600 hops/sec.

Jim Kardach, a student of Norse history, named Bluetooth after Harald Bluetooth, king of Denmark between 940 and 981.  During his rule, Bluetooth united Denmark with Norway.  He is said to have brought Christianity to the two countries.

Kardach used the analogy that Bluetooth 'allowed greater communication between people' when naming the system.  It was common for the Danes and other Norse peoples to name their heroes after physical attributes, and historians speculate that his own 'blue tooth' referred to a rotten tooth.

Bluetooth himself is thought to have been ousted by his son Sweyn Forkbeard.

A physical reminder of Harald Bluetooth are the two Jelling stones, massive carved runestones from the 10th century, found at the town of Jelling in Denmark.  The older of the two Jelling stones was raised by King Gormthe Old, Bluetooth's father, in memory of his wife Thyra.  The larger of the two stones was raised by Bluetooth in memory of his parents.

T.Finch, Harrogate, N. Yorks

(from  Answers to Correspondents, compiled by Charles Legge, Daily Mail, Wed 16 June 2015)

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What is 1 kilobyte? — 1024 bytes or 1000 bytes?

BOTH definitions can be correct — it depends on the context. Computers are binary systems where the smallest unit of information is the bit, which can have two states, either on or off, 0/1. Bits are organised into bytes, which are eight bits.

When working with binary multiples where two is increased by a power, the closest to the Si (International System of Units) definition of a kilobyte is 1024 bytes or two to the power of ten.

The 1024 bytes definition is used for memory addressing in ram, the 1,000 bytes definition (ten to the power three) is used for data transfer rates or a DVD's storage size. The values are denoted with a lowercase k in kB for 1024 bytes and an uppercase K in KB for 1000 bytes.

Mark Brougnton, Bedford.

(from  Answers to Correspondents, compiled by Charles Legge, Daily Mail, Wed 11 Feb 2015)

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