Hig and low word

What is high word and low word. Can anyybody explaint it. Please.

Any type of computerized device, a PLC for example, stores numbers in groups of bits. A certain number of bits can be stored at one time. Current PLC's typically store numbers in 16 bit groups.

When the representation of a number occupies more bits (usually twice the number of bits) then half of them must be stored in one memory location and half in another. The two locations are typically adjacent in memory.

If 16 bits of memory are considered a 'word' then the full number consists of one 'word' which contains the least significant bits and one 'word' which contains the most significant bits.

The design of computer memory storage has varied. In some the least significant bits are stored in the memory address which has the lower number (low word) while the most significant bits are stored in the memory address which has the higher number (high word).

But some store the words the other way around. ('Low word' containing the most significant bits, 'high word' containing the least significant bits.)

Please refer to this wiki entry for a discussion of 'endianness'

There are also concerns during data serial transmission on the order of transmission of multi-byte numbers.

I'd disagree. I'd say the low word is always the least signifcant 16 (or whatever) bits, and the high word is always the most significant. It doesn't matter which order they are stored in. The low and high refer to the significance, not the memory position.

I have seen the terms (low and high word) used both ways. I hope we haven't confused him. Possibly just the idea of the least significant and most significant portions of a value being separate items may be enough.

I agree with Mike

The term endian is used to describe the order of the words or bytes with a larger data type.