1.1 Processors extra Flashcards
Where does control bus transmit control signals between
Control unit and other parts of the processor
Explain the need for the PC
stores address of next instruction, value sent to MAR and then PC increments to next value
Is there such thing as an interrupt register
Yes
What does all data to be saved use?
The accumulator
What does the CIR do with the address and data
Sends data to MDR and address to MAR where they act as a buffer
Role of control unit
Decodes instructions and sends signals to coordinate movement of data through the processor
How is address bus used
Transfers memory location to allow the data to be accessed
How does fast clock speed improve performance
Allows for more FDE cycles per second therefore more instructions can be executed per second therefore the program takes less time to run
How does large cache size improve performance
More space for data/instructions in cache therefore RAM accessed less and cache is quicker to access than RAM
How would updating an OS increase performance
OS release updates which improve performance
What affect would a lighter weight OS have on performance
Use fewer resources
Why would defragging disk improve performance
As data would be stored contiguously and would be quicker to access as physical head would be able to read the data in one location
Malware and spyware on performance
Decreases performance
More RAM on performance
Less need for slower virtual memory
Why would GPU speed up rendering?
As GPU has specialist instructions and can apply same instructions and can apply same instructions to multiple pieces of data at same time
Remember to talk about what on an LOR suggesting something
Cost
Describe one issue BRP causes for a CPU using pipelining
BRP could be followed by 2 instructions which will only be determined at execution so wrong one may be fetched/decoding
Explain another advantage other than cost of RISC compared with CISC
Programs run faster due to simpler instructions
Why is CISC more expensive?
Integrated circuit(expensive)
complex processor(expensive)
What is more available with CISC?
Many addressing modes and instructions are available
What is limited RISC?
Number of instructions
How are complex tasks completed with RISC
Multiple instructions are combined
Another example of RISC
Programs run faster due to simpler instructions
Explain the effect of using a co-processor for complex calculations for scientific research
Calculations done by maths co-processor so processing is faster when using floating point arithmetic
Explain the effect of using a co-processor for an advertising campaign
No increase in speed as no calculations
Three other features of von neuman
One control unit
One instruction at a time
Program and data stored together?
What is one of the main differences between RISC and CISC
RISC uses fixed number of bytes whereas CISC uses variable number of bytes
What happens in execute phase
Opcode carried out on operand
What is RAM apart of
Primary memory
Why is a GPU more suited for 3D rendering than a CPU
CPU’s are general purpose whereas GPU’s are designed for graphics so will have built in instructions for common graphics operations
How does multiple cores speed up processed
Speed up smaller problems but will not be enough for larger problems
When are GPU’s useful
On highly parallelisable problems but only where the same instruction is being applied to multiple pieces of data
What is it called when the same instruction is being applied to multiple pieces of data
SIMD
How can multiple computers work together
Distribute workload across computers
Why is increasing clock speed limited
Limited to smaller problems, most problems are only partially parallelisable
Use for hard drive
To store files and software
Use of removable hard drive
To store archive of files
Use of CDROM/DVDROM reader
For the importation of software
Use of Memory stick/SSD
To allow transport of materials between office and home
Use of optical disk
To store back-up of files/software
Use of cloud storage
To make files available to others in the dept, from anywhere on any device whilst also providing a backup
Do SSD’s have a lower or higher power consumption that hard drives
Lower due to no moving parts
Hard drives and sound
Can be noisy due to fast moving parts which can be undesirable
SSD and sound
Silent
Advantages of ROM
Quick to start up so the system can be started up quickly and ROM cannot be altered so no chance of OS being maliciously changed on what is a safety critical system
State one item that needs to be stored in RAM and give a reason why RAM is used
User files/software as user must be able to alter contents of file. RAM offers direct access and operates at faster speeds than secondary devices
What can damage hard drive when movement occurs
Head coming into contact with platter
Which takes up more physical space, hard drive or flash memory
Hard drive due to moving parts where as flash has no moving parts
What is the stored program concept
A program must be resident in main memory to be executed and the the instructions are fetched from memory one at a time
Other examples of where Harvard architecture is used (sound/speech)
audio and speech signal processing
Example of how in Harvard architecture, memories can have different characteristics
In embedded systems, instructions held in read only memory whereas data requires read write memory
Example of how in Harvard architecture, memories can have different sizes
Some systems have more instruction memory than data memory so larger word size used for instructions therefore instruction address bus will be wider
Where is Von Neumann architectures used
Conventional processors in PCs and servers
What type of embedded systems is Von Neumann used in
Embedded systems with only control functions
Where is Harvard architecture used
Digital signal processing, mobile communication and embedded systems
What is the processor hardware capable of doing in CISC
Understanding and executing the series of sub-tasks that make up a single instruction
What is the distinguishing feature of a CISC instruction
Combines a load/store instruction with the instruction that carries out the actual calculation
Advantage of CISC in relation to the compiler
Compiler has little work to do to translate into machine code because the code is short therefore little RAM required too
Disadvantage of CISC in link to specialised instructions
Many had to be built into the hardware even though only about 20% of them were used in the average program
What is a co-processor used for
Floating point arithmetic, graphics processing
What is the improvement in performance gained using a multi core processer dependant on
The software being able to take advantage of parallel processing capabilities
Jump instruction
used to alter the normal sequence of program execution by unconditionally transferring control to a specific memory address
What is threading
Threading is usually referred to having multiple processes working at the same time on a single CPU (well actually not you think they do but they switch very fast between them)
What is parellelism
Parallelism is having multiple processes working at the same time on multiple CPU’s.
What are pages
is a fixed-length contiguous block of virtual memory, described by a single entry in a page table
What does the line MULT A, B do in LMC?
Multiplies A and B and stores the result back into A.
How is a CISC instruction stored?
A CISC instruction combines a “load/store” instruction with the instruction that carries out the actual calculation
CISC and complexity of processor circuit
More - circuitry only has to deal with complex instructions
CISC number of clock cycles per instructions?
One instruction takes multiple cycles.
RISC number of clock cycles per instructions?
One instruction takes one cycle (ideally) so pipelining is possible
CISC Complexity of CPU instructions?
More complex instructions like multiply lots of instructions don’t get used.
RISC Complexity of CPU instructions?
Simple instructions like load, store instructions are often used.
RISC and complexity of processor circuit
Less - circuitry only has to deal with simple instructions
Power consumption (relative to each other) CISC
Higher due to complex circuitry and high clock speeds
Power consumption RISC
Lower due to simpler circuitry and lower clock speeds
Cost (relative to each other) CISC
More (complex circuitry is more expensive to design and make)
CISC complexity of source code for equivalent programs?
Less complex (code for a factorial function will be much simpler in Java than LMC)
Number of addressing modes (relative to each other)
CISC
More
Number of addressing modes (relative to each other)
RISC
Fewer
Uses of CISC
Laptops. desktops
Mobile phones
Smartphones tablets
RISC complexity of source code for equivalent programs?
More complex (code for a factorial function will be much simpler in Java than LMC)
CISC size of code for equivalent programs?
Smaller (think how much shorter a factorial program would be in Java v LMC)
RISC size of code for equivalent programs?
Larger (think how much longer a factorial program would be in assembly v LMC)
CISC RAM required when loading equivalent programs?
Less (program will be shorter therefore need less RAM)
RISC RAM required when loading equivalent programs?
More (program will be longer therefore need more RAM)
