Hardware Flashcards
What are buses?
Buses are wires used to connect different components of the computer’s hardware.
What is an Address Bus, Data Bus and Control Bus?
The address bus carries the address of the piece of memory or I/O device. It is a unidirectional bus, meaning that data travels only one way: from the CPU to memory.
The data bus carries the data that is to be written or has been read from memory. It is a bidirectional bus as it can carry data to or from memory.
The control bus carries signals that control the actions of the computer.
What is Non-volatile Memory?
Non-volatile Memory is retained even if the power to the computer is shut off.
Read Only Memory (ROM), generally installed by the vendor of the computer, it retains code that is required to start and run the computer and it cannot be lost or changed when the computer is turned off.
What is Volatile Memory?
Volatile Memory is lost when the computer loses power. Random Access Memory (RAM) is the form of volatile memory used to hold temporary instructions and data for manipulation while the system is running.
What is the CPU?
The Central Processing Unit (CPU) is the part of the computer that executes instructions. CPUs are constructed from millions of transistors.
A CPU has three main components, the Arithmetic and Logical Unit (ALU), the Control Unit and the Registers.
What is the Arithmetic and Logical Unit (ALU)?
The ALU carries out the mathematical functions.
What is the Control Unit?
The Control Unit regulates the flow of information through the processor. The Control Unit determines how and when data is processed and ensures that it is sent to the correct components of the computer.
What are Registers?
What is the Instruction Register?
What is the Memory Address Register?
What is the Memory Data Register?
What is the General Purpose Registers?
What is the Program Counter?
Registers are small pieces of memory located inside the CPU. They can be thought of as the hardware version of a variable in software.
Instruction Register (IR): The instruction register holds the instruction currently being executed.
Memory Address Register (MAR): The memory address register holds the address of the next piece of memory to be fetched.
Memory Data Register (MDR): The memory data register holds the piece of data that has been fetched from memory.
General purpose registers are available to store any transient data required by the program. For example, when a program is interrupted its state, ie: the value of the registers such as the program counter, instruction register or memory address register – may be saved into the general purpose registers, ready for recall when the program is ready to start again.
The program counter holds the location of the next instruction to be fetched from memory.
Explain the difference between SRAM and DRAM
Static RAM (SRAM) is physically different from dynamic RAM as the memory contents do not have to be continually refreshed. This means that it can always be accessed and so SRAM is a faster type of memory. However the process of manufacturing the memory and the components used make it more expensive. It is mainly used as cache.
DRAM is the most common type of RAM used in computers. It is relatively easy to manufacture and so is cheap. However, DRAM contents must be continually refreshed
CPU characteristics
1) bit width
2) clock cycles
3) execution cores
The bit width approach describes a processor in terms of how many bits it processes in a single instruction or transports across the processor’s internal circuits in a single cycle.
The clock cycle describes how many times per second an electrical charge passes through the chip (gigahertz).
Additional execution cores mean that you can run more applications at the same time.
What is a storage device?
A storage device is any device used by a computer to store information permanently
hard disk drives
hard disk drives (HDDs), non-volatile devices that store information on magnetic platters
What is Input/Output referred to?
Input/Output (I/O) is the process of transferring data between a computer and its peripherals. A peripheral is any piece of equipment attached to a computer. For example a mouse, keyboards, printers, etc
Peripherals are connected via the I/O bus.
In order for the CPU to correctly identify the communicating device each device is assigned a unique address.
Explain how the width of the address bus determines how much memory can be addressed in a PC.
The number of lines on the bus determines the number of addressable memory elements. For example an 8 bit bus can represent 2 to the power of 8 unique addresses. This equates to 256 unique memory addresses.
Explain how the width of the data bus determines how much data can be moved in a PC, in one clock pulse.
It determines how much data it can transfer in one clock pulse. 32 bit data bus can transfer 32 bits of data per clock pulse and a 64 bit data bus can transfer 64 bits per clock cycle
