Abstract: A computer access system includes a password generator (10) and an lock computer (50) connected to receive passwords generated by the password generator and grant access to a host computer (52) when a password from the password generator (10) matches a password separately generated by the lock computer (50). The password generator (10) and the lock computer (50) have corresponding pseudo-random number sequences stored in memories (26 and 90). The password generator (10) and the lock computer (50) have synchronized clocks (30 and 84), which define time intervals. During a given time interval, entry of a personal identification number in password generator (10) will cause the password generator (10) to generate a unique password from the random number sequence in memory (26) and time interval information from clock (30).