Next, we can consider the effect of the data transfer rate of information on the magnetic tape unit to the batch terminal. Two factors govern the magnetic tape unit data transfer rate since the rate at which data can be transferred between the terminal’s memory and the tape unit is equal to the number of characters per inch recorded on the tape times the number of those inches that pass the read head second. In addition, the number of characters recorded per inch of tape is dependent upon the record length and blocking factor originally employed to build the tape. From a systems standpoint, if DTR1 is the data transfer rate from the magnetic tape to the terminal and DTR2 is the data transfer rate from the terminal to the communication line, then, for DTR1 < DTR2, there is nothing to gain by introducing a compression routine or routines unless another modification to the hardware or software will be implemented to take advantion of the magnetic tape to increase its blocking factor of the procurement of higher recording density and faster read/write head tape units would permit a higher data transfer rate. Form a communications standpoint, one may let DTR1< DTR2 continue to exist but incorporate compression to lower DTR2 and thus save line and modem costs by reducing the communications data transfer rate while maintaining the overall effective information transfer ratio.