aqa AS COMPUTER SCIENCE Paper 1 (7516/1) May 2023 Question Paper

aqa AS COMPUTER SCIENCE Paper 1 (7516/1) May 2023 Question Paper 1. A security system uses a motion sensor, a keypad and an alarm bell. The system operates as follows: • the system is initially off • when the system is switched on it goes into sensing mode • the system can be switched off at any time by entering the correct code on the keypad • if the system detects movement while in sensing mode it goes into alert mode • after the system has been in alert mode for 10 seconds, it enters the alarm bell ringing mode • if an incorrect code is entered on the keypad, once the system has been switched on, the system remains in its current mode. Figure 1 shows a partially completed state transition diagram that represents the operation of the security system. Three of the states are labelled (X) to (Z) and events are labelled (A) to (I).