A company is connecting hardware to an office computer. The computer has a CPU, main memory, an input device and several output devices. Data must move betw...
Question 1 Report
A company is connecting hardware to an office computer. The computer has a CPU, main memory, an input device and several output devices. Data must move between these components while a program runs. A bus is a set of wires or connections that carries signals. The address bus identifies a memory location or hardware device, the data bus carries data and instructions, and the control bus carries signals such as read, write and interrupt. The data bus in this computer is 16 bits wide. The diagram is incomplete and shows the CPU linked to main memory and an input/output (I/O) controller. An interrupt can be sent by the I/O controller when, for example, a key is pressed.
(a) State the name of the bus that carries a memory address from the CPU. [1]
(b) State the name of the bus that carries the value read from memory to the CPU. [1]
(c) Identify the bus that carries a read signal. [1]
(d) Give one reason why an address bus normally carries signals in one direction only. [1]
(e) Explain the purpose of the interrupt signal shown in the diagram. [2]
(f) Complete: a 16-bit data bus can transfer ______ bits in one bus transfer. [1]
(g) Convert the binary value 10110110 to denary. [2]
(h) Give two examples of an input device that could be connected through the I/O controller. [2]
(i) State two components found inside a CPU, other than the clock. [2]
(j) Give two possible effects on computer performance of increasing the clock speed. [2]
Answer Details
(a) The address bus carries a memory address from the CPU [1].
(b) The data bus carries a value read from memory to the CPU [1].
(c) A read signal travels on the control bus [1].
(d) The CPU sends an address to select a memory location or device; memory does not need to send an address back on the address bus, so it is normally one-way [1].
(e) An interrupt informs the CPU that an event needs attention, such as a key press. The CPU can pause its current task at a suitable point and run the appropriate interrupt service routine [2].
(f) A 16-bit data bus transfers 16 bits in one transfer [1].
(g) \(10110110_2=128+32+16+4+2=\textbf{182}\) [2].
(h) A keyboard and a mouse are valid input devices [2].
(i) Two CPU components are the ALU and control unit [2]. Registers or cache are also valid.
(j) Increasing clock speed can allow more cycles per second and hence faster instruction processing, but can increase power consumption and heat production [2].
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