MVvsdataF

Memory Variable

The memory of a computer is organized into a regular pattern of containers for information. These containers for information are called "words". Each one has a numeric address and each one is the same size as each of the others. For most applications, it is inconvenient to refer to portions of memory by their numeric addresses, so programming languages allow us to allocate portions of memory by name. When we store information in the memory of a computer we need to decide on how much we need for various purposes and on how it will be organized. Programming languages provide mechanism for "types" of information in memory. They also provide mechanisms to identify repetitive arrays of items of the same type and to aggregate possibly heterogeneous types under a common name.

 

Portion of word	Number of bits
nibble	4
character	8 or 16
byte	8
octet	8
half-word	16
word	32

The ambiguity on the size of characters is because we are in a time of transition to richer and more complex character sets for which the limit of 256 characters imposed by an 8-bit character size is inappropriate. We may also be starting on a transition to 64-bit words. Time will tell.

Data Field

A data field is a place where you can store data. Commonly used to refer to a column in a database or a field in a data entry form or web form.

The field may contain data to be entered as well as data to be displayed.

The data-store is composed of a number of data records which are, in turn, composed of a number of predefined data fields. Each of these data fields must be defined within the Load Definition File with a unique name.