difference between common control and direct control switching system
Common control Systems which have control subsystem as an integral part of the switching network itself were known as direct control switching systems. Systems in which the control subsytem is outside the switching network are known as Common control systems. Strowger exchanges are usually direct control systems, whereas crossbar, electronic exchanges including all stored program control systems are common control systems. Common control is also known as indirect control or register control.
Direct-shift gearbox The direct-shift gearbox uses a floor-mounted transmission shift lever, very similar to that of a conventional automatic transmission.[10] The lever is operated in a straight 'fore and aft' plane (without any 'dog-leg' offset movements), and uses an additional button to help prevent an inadvertent selection of an inappropriate shift lever position.