The writetx statement writes a tape record, converts the string from ASCII hex to binary, and copies the string to the tape buffer.
writetx var[then|else|onerr statement.block]
The length of the tape record is specified by the most recently executed TCL t-att command.
If the tape unit has not been attached or if an end-of-file (eof) mark is read, the else or onerr clause, if present, is executed. In addition, the onerr clause can be used to check for end-of-tape (eot), tape unit not ready, parity error, or block transfer error.