EXCHTYPE parameter

You use the Exchange Type (EXCHTYPE) parameter to specify which one of the three diskette exchange types (basic, H, or I) the system will use when writing diskette files. The exchange type will be stored in the volume label area on the diskette. There is one label for each data file on the diskette.

You can specify the exchange type to be used in one of the diskette device file commands (Create Diskette File (CRTDKTF), Change Diskette File (CHGDKTF), or Override Diskette File (OVRDKTF)). It can also be passed as a parameter when the device file is opened by the high-level language program (if supported).

The system will not use the exchange type specified in the diskette device file or high-level language program when processing a diskette input file. Instead, the system will use the exchange type from the file label on the diskette.

It is possible for one diskette to contain both basic and I exchange format files or H and I format files. One diskette cannot contain both basic and H format files.

Values allowed

You can specify one of the following values for the EXCHTYPE parameter, depending on the diskette type (1, 2, or 2D) and the diskette sector size (128, 256, 512, or 1024 bytes):

*STD: The system determines the exchange type based on the diskette type and sector size. A basic exchange type is used if the diskette type is 1 or 2, and the diskette sector size is 128 bytes. An H exchange type is used if the diskette type is 2D and the diskette sector size is 256 bytes. The *STD value is not valid for any other combination of type and sector size.

*BASIC: The basic exchange type is used. The diskette type must be 1 or 2, and the diskette sector size must be 128 bytes.

*H: The H exchange type is used. The diskette type must be 2D, and the diskette sector size must be 256 bytes.

*I: The I exchange type is used. The diskette type and sector size may be any of the following:

Diskette type

Sector size (bytes)

1

128, 256, or 512

2

128, 256, or 512

2D

256, 512, or 1024