Various codes can be used for writing and reading magnetic tapes. The data and the labels of tape files are processed in the specified code. The code is a file attribute. Labels are also checked in the specified code.
The following operands in the FILE/FCB macro or the ADD-FILE-LINK command specify the code for SAM/BTAM:
CODE = EBCDIC | No code conversion |
CODE = ISO7 | ISO 7-bit code (128 text characters) |
CODE = OWN | All other codes |
In EBCDIC and ISO7 code, the national and international character sets are encoded with the same bit combinations (double assignment).
If the CODE operand is not specified in the FILE/ FCB macro or in the ADD-FILE-LINK command, the specification is taken from the catalog entry for the file or from the tape label.
As a rule, the codes EBCDIC and ISO7 are recognized. If CODE=OWN is entered, labels are recognized only if a conversion table is provided in the user program. Separate conversion tables (256 bytes each) must be provided for writing and reading. The addresses of the conversion tables for reading and writing are specified in the FCB with the operands TRTADR (TRanslate Table ADdress Read) and TRTADW (TRanslate Table ADdress Write).
The user can also specify that tape files in any code are to be read directly (without conversion, as for EBCDIC).
Once the code has been specified, the user does not need to worry about the details of code conversion. He can assume that the data traffic with the tape file will be executed just as for an EBCDIC file.