IGCSE Computer Science Paper 1 Word Scramble: 4.1 Types of Software and Interrupts (Modules 409–418)
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Word scramble
Unscramble the letters and write each key term on the line.
1
ENTPITURR ECSOUR
The origin of the signal. From a device, like a key press or mouse move, it is a hardware interrupt. From a running program, like divide by zero or a memory clash, it is a software interrupt.
2
RUTITRNEP ANILSG
A signal sent to the CPU by a device (hardware) or a running program (software) when an event, such as a key press, needs the CPU's attention.
3
TTRNERUIP KCECH
At the end of each fetch-decode-execute cycle the CPU checks for an interrupt signal. If none, it fetches the next instruction; if one, it switches to handling it first.
4
TIRENRTPU RITORIYP
Each interrupt has a priority level. The CPU handles the most urgent one first, so a power failure can pause the handling of a less urgent key press.
5
ESAV ERESITGR NSOTNCET
Before running the ISR, the CPU stores its register contents, including the program counter, so the interrupted task can later carry on exactly where it stopped.
6
TETNURIRP MTUCEOO
What the ISR does depends on the event: it reads a key press, updates the pointer, shows an error or stops a faulty program. Then the CPU resumes the task it was running.
7
SO TRRUPITNE AINGNHDL
The OS receives each interrupt, picks the right ISR to run, manages priorities, then passes control back to the interrupted program so it can carry on.
8
ONTIP NDA ARESNO
A full-mark answer uses the correct terms (system software, firmware, bootloader, ISR), gives points in the right order, and adds a reason for each point.
Answer Key
IGCSE Computer Science Paper 1 · Modules 409–418
1ENTPITURR ECSOUR → interrupt source — The origin of the signal. From a device, like a key press or mouse move, it is a hardware interrupt. From a running program, like divide by zero or a memory clash, it is a software interrupt.
2RUTITRNEP ANILSG → interrupt signal — A signal sent to the CPU by a device (hardware) or a running program (software) when an event, such as a key press, needs the CPU's attention.
3TTRNERUIP KCECH → interrupt check — At the end of each fetch-decode-execute cycle the CPU checks for an interrupt signal. If none, it fetches the next instruction; if one, it switches to handling it first.
4TIRENRTPU RITORIYP → interrupt priority — Each interrupt has a priority level. The CPU handles the most urgent one first, so a power failure can pause the handling of a less urgent key press.
5ESAV ERESITGR NSOTNCET → save register contents — Before running the ISR, the CPU stores its register contents, including the program counter, so the interrupted task can later carry on exactly where it stopped.
6TETNURIRP MTUCEOO → interrupt outcome — What the ISR does depends on the event: it reads a key press, updates the pointer, shows an error or stops a faulty program. Then the CPU resumes the task it was running.
7SO TRRUPITNE AINGNHDL → OS interrupt handling — The OS receives each interrupt, picks the right ISR to run, manages priorities, then passes control back to the interrupted program so it can carry on.
8ONTIP NDA ARESNO → point and reason — A full-mark answer uses the correct terms (system software, firmware, bootloader, ISR), gives points in the right order, and adds a reason for each point.