If the terminals connected to the concentrator are used for time sharing, their typical message length is 32 characters which takes 32/150 or 0.213s to reach the concentrator from the terminal. To send that message from the concentrator to the host computer requires 32/7000 or 0.004 57 s. The difference between the time it takes the concentrator to receive the message and transmit the message is 0.208 76s and can be considered a ‘window of operation’. This is the amount of time available for all concentrator processing to include data compression prior to a message transmission delay resulting.
If we assume a 2 us cycle time and 4 cycles per instruction, then a time of 8*10-6 s is required to execute an instruction. Dividing that figure into the previously computed window of operation results in 26 095 instructions which can be performed upon the data prior to a message transmission delay occurring. If one knows the current number of programmed instruction in the concentrator software, that number can be subtracted from 26 095 to determine the number of data-compression instructions that can be written prior to causing a message transmission delay.