With a motivation to understand all the fifteen test algorithms and to write their codes independently without looking at various sites mentioned in the NIST document a review study of the NIST Statistical Test Suite is undertaken. All the codes are executed with the test data given in the NIST document and excellent agreements have been found. The codes have been put together in a software, called as CU software, executable in Linux platform. Based on the CU software, exhaustive tests are executed on a long bit sequence generated by the Blum‐Blum‐Shub generator (BBSG). The CU software executes properly giving the results almost matched with those of the NIST results.