Shift registers

New technologies are causing the number of ICs working at the long-established ‘TTL’ (transistor-transistor logic) to decrease rather alarmingly. The process is not one of gradual substitution, designers being faced with ICs having different voltage swings for their logic levels. It may happen that a certain type of shift register employing TTL levels is suddenly no longer available. This Design Tip presents an example of how to approach and solve the problem.