| IOT Code | Abbreviation | Function |
| 73....nn 60 | mrb | Read a binary record. |
| 73....nn 61 | mra | Read an alphanumeric (BCD) record. |
| 73....nn 62 | mbb | Backspace a binary record. |
| 73....nn 63 | mba | Backspace an alphanumeric record. |
| 73....nn 64 | mwb | Write a binary record. |
| 73....nn 65 | mwa | Write an alphanumeric record. |
| 73....nn 66 | mlp | Move tape to lead point (rewind). |
Where the octal digits, nn, specify the unit number.
The motion commands have the deferred bit, thus, the program halts. If the TC is free, the command will be transferred to the tape control for action and the program restarts immediately. If the tape control is currently busy with an instruction, i.e., it hasn't finished a previous command, the motion command is held up until TC is free to execute the new command.
The transfer of information from the computer to the TC is accomplished with the pause and skip command, MPS or IOT 70. This command has the deferred bit and halts a program until the TC can handle the transfer. On completion, the transfer occurs and the program restarts. This is used exclusively to synchronize the flow of information between a tape unit and the computer. This command normally skips the following instruction. If a flag is set in the TC, indicating incorrect information flow, the skip does not take place.
The TC contains a 36 bit buffer which holds a complete word while information is read or written. When an MPS order is given and the unit is reading, the TC buffer is read into the IO. The MPS order given during writing causes the IO to be transferred to the TC buffer.
Various conditions occurring in the TC cause the no-skip condition, when an MPS is given. Tape control flags are examined by the command, examine and clear flags, MEC or IOT 71. When MEC is given, the flags are put into the IO for program interrogation, and the flags cleared. The flags are: parity, end of tape, an end of record flag, and reading-writing check.
The parity flag is set if the parity condition is not met while the tape is being read (during MWA, MWB, MRA, or MRB).
The end of tape flag is set when the tape comes to the end of tape, moving in either direction.
Three conditions set the read-write check flag: 1) If TC is inactive, i.e., no unit or function selected, and an MPS instruction is given. The MPS becomes a no-operation, no-halt instruction. 2) When reading information and not emptying the TC buffer, by giving an MPS before more information arrives from tape. 3) A unit becomes unavailable during a normal sequence.
The end of record flag is set during reading or backspacing when the tape comes to an end of record gap.