What does BCD mean?

Answer 1

BCD actually stands for "Buoyancy Control Device". It is the device that often looks like a cross between a life jacket and a waistcoat that a Scuba diver wears on top of his/her wetsuit. It has a whip (hose) connected to the divers first stage (this is the metal piece that attaches to the top of the divers cylinder). This whip carries air at 1 Bar above the ambient pressure to the diver BCD. When the diver is in the water he/she may need to press a button on the BCD to inject air from the cylinder to the BCD thus aiding the diver in controling buoyancy. The diver usually needs to be neutrally buoyant in the water so the BCD is used to do this. There is also a "Dump valve" on the BCD to dump air. When a Scuba diver enters the water you may see him/her holding a hose in their arm upright as they first leave surface. This is the dump from the BCD to force the air out to aid decent. There is also an additional independent cylinder on the BCD to do inflate so that the breathing air does not need to be consumed. I have been a professional diver on the oil industry for over 18 years so I hope I have explained the answer to your question properly. Greg

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BCD (Binary Coded Decimal) in computer programming is a method of storing decimal numbers in a binary form. Each byte (8 bits) of data is divided into two 'nibbles' (four bits).

Each nibble of data can store the number 0 - 15 in decimal in it, however using special assembly language op codes, each nibble of data can be forced to set the carry bit in the status register and zero its contents when it increments past the decimal value 9. This allows for decimal notation in a binary system.

BCD numeric systems were originally used in the late sixties and early seventies in calculators using a four bit accumulators and in electronic clocks but these days programmers rarely use the method.

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