Systems Architecture Flashcards
What are the main components of a computer?
CPU (central processing unit), main memory, secondary storage, input devices, output devices
What is the purpose of a CPU?
The purpose of the CPU is to process data and execute programs
What are the components of a CPU?
Control Unit, Arithmetic Logic Unit, RAM (main memory), Buses, Registers, Clock
What is the ALU?
The Arithmetic Logic Unit (ALU) performs all the arithmetic operations and logical decisions
What is the CU?
The Control Unit uses electrical signals to control the timing and the flow of data around the CPU. It is responsible for fetching and decoding instructions so that they can run on the processor.
What is RAM?
Random Access Memory (primary storage) is the main memory of the computer where programs, data and operating systems are stored when the computer is in use.
What are buses?
They are just sets of wires, used to transfer data and signals between the CPU and memory
What are the different buses and what do they do?
Control bus - carries control signals to tell the memory or the processor what to do next
Address bus - carries memory addresses from processor to memory
Data bus - carries data and instructions both ways between memory and CPU
What is Von Neumann Architecture?
Computer programs and data are stored in the SAME RAM memory
What are registers?
Registers are extremely small, extremely fast memory located in the CPU that hold small amounts of data needed as part of the fetch-execute cycle. Each register has its own specific purpose.
What is the purpose of the clock?
The clock keeps related components in sync by generating pulses at a constant rate.
What are the different registers and what are their purposes?
Program Counter (PC) - holds the address of the next instruction to be executed
Current Instruction Register (CIR) - holds the current instruction
Memory Address Register (MAR) - Holds the addresses that are about to be sent down the address bus to memory
Memory Data Register (MDR) - Holds data or instructions that have travelled up the data bus from the memory
Accumulator (ACC) - Holds the result of the most recent calculation by the ALU.
What is Cache?
Cache is memory that is similar to RAM, but is much faster and therefore more expensive. It is located very close to the CPU
Cache memory is temporary storage for frequently used data.
What are the 4 things that affect how well your processor works?
Cache memory (size and speed)
Clock Speed
Number of cores (multiple cores)
Speed of Memory/RAM
Speed/size of any secondary storage.
How does clock speed affect how well the processor works?
The faster the clock speed, the faster the computer can perform the FDE cycle resulting in better performance because more instructions can be processed each second.
What is a dual core processor?
Two processors working independently at the same time
They will fetch, decode and execute programs simultaneously
Therefore they can process more instructions at one time - if that can be programmed
Will multiple core processors run faster than a singular one?
Not necessarily, as software may be designed to only run on 1 core, some tasks cannot be split over multiple cores. Other things also affect speed of processor.
What is an embedded system?
An embedded system is a computer system with a dedicated function, built into a larger system/machine (to provide a means of control). They have a limited range of functions, its OS and software is in ROM, and its functionality won’t change.
What is a non-embedded system?
A non-embedded system is a computer system with multiple functions, referred to a general purpose machine.
What are the differences between an embedded and non-embedded system?
An embedded system is typically:
smaller in size
lower power
lower cost
lower processing power
lower memory
What are the characteristics of an embedded system?
An embedded system often uses a single microprocessor on a circuit board, and its OS and software is stored in ROM (aka firmware).
They are a small system built into a larger system.
Embedded systems have limited functions, and can’t easily be changed.
And embedded system is frequently used to control a device using limited inputs and outputs.
They’re often invisible to the user.
What are some examples of an embedded system?
Heating thermostats
Dishwashers
Washing machines
Coffee machines
Traffic lights
Hospital equipment
What are the three operations in the Fetch-Execute cycle?
Fetch - causes the next instruction and any data involved to be fetched from main memory
Decode - decodes the instruction
Execute - carries out the instruction
Describe the process of the Fetch operation in the Fetch-Execute cycle.
- Firstly, address of next instruction copied from PC into MAR
2a. The contents of the MAR are sent down the address bus. A READ signal is sent down the control bus. the main memory looks at what is in that memory location and sends it up the data bus to the MDR
2b. At the same time, the PC is incremented(goes up by 1) - because it always holds the address of the NEXT instruction - The instruction in the MDR is copied to the CIR
