Sharp MZ-700 Basic Manual page 12

11
• Data file control
There are two types of data files, depending upon the format of file access (the method
of data read-out and write-in). One
is
called the sequential access file and the other is
called the random access file.
With the sequential access file, the file data access is treated as one sequential block.
The file name is specified for one group of data, and such data are accessed in order
from the heading at the time of registration or read-out of the file.
For the random access file on the other hand, the filed data are accessed at random.
One random access file is composed of one data group designated by its own file
name. Each group of data is registered in the file in a parallel arrangement, and
write-in and read-out of each data group is possible by using the number (expression)
assigned to that data.
If, for example, a collection of certain data can be handled as a connected group (such
as, for example, data consisting of a series of decimal expressions used when producing
machine language programs by BASIC POKE command and elements of tables that
can be presented in order from the heading, etc.), collection of such data in a
sequential access file can be useful and effective. The registration of data in a random
access file, on the other hand, can be useful when it is necessary to not only consider
the group of overall data but to read-out and/or write-in each element (when it is
necessary, for example, to rewrite data or to search, arrange, delete, etc.).