Disk File Types
A disk file is any file that resides on a hard disk or floppy diskette. (Some systems provide a "RAM disk" feature that uses memory to simulate a disk. A RAM disk is treated the same as any other disk by PRO/5.) A single disk may contain many files. The files are located in a directory. Each file will occupy some region on the disk. Some systems require files to exist within fixed regions, while other systems allow files to increase in size dynamically as more space is needed. PRO/5 will work completely within the designated region allocated for each file to build its information structures. PRO/5 provides the following information structures or "file types":
|
File Type |
Access by |
Description |
|
C-ISAM |
KEY=, KNUM= |
Fixed record size, dynamic number of records only. No IND= access. |
|
KEYED DIRECT |
KEY=, IND= |
Fixed record size, file size. |
|
DIRECTORY |
must READ RECORD |
Sequential read returns next file name. No access by index or key. |
|
INDEXED |
IND= |
Fixed record size, dynamic number of records. No KEY= access. |
|
MKEYED |
KEY=, KNUM= |
Fixed record size, dynamic number of records. No IND= access. |
|
PROGRAM |
IND= |
BBx programs that can be loaded and saved in the interpreter with LOAD and SAVE commands. |
|
SERIAL |
IND= |
String file with header, size of each record saved at beginning of record (invisible to user). No KEY= access. |
|
KEYED SORT |
KEY=, IND= |
DIRECT file with no record data, fixed file size. |
|
STRING |
IND="flat" file |
No records, must READ RECORD with SIZ=. IND= refers to the byte position in the file and can be field oriented. No KEY= access. |