The 74393 is a counter integration with two 4-bit counters.
MR inputs are reset (reset) by triggering LOW-->HIGH high edge.
CP input is HIGH--->LOW falling edge triggered Clock-clock input. Since there are two 4-bit counters in a 74393 IC, when the clock-clock input applied to pin "1" is connected to pin "13" from the QD output of the 4-bit counter, a total of 8 bits is obtained.
When two 74393 cascades are connected, a total of 8+8=16-bit counters is obtained. The connection of two 74393 counters related to the subject is shown in the picture.
The 74393 counter can be operated with a maximum clock of 45 MHz.