computing components Flashcards
What is the stored program concept?
The stored program concept means that data and instructions are both logically the same and can both be stored in memory.
The von Neumann architecture is built around this principle. It is important because the human does not have to execute instruction from without the machine.
What are the 5 components of Von neumon architecture?
- The memory unit that holds both the data and instructions, as they are logically the same.
- The ALU that performs arithmetic and logic operations on the data.
- The Input unit that moves data from the outside world into the computer.
- The output unit that moves data from inside the computer to the outside world.
- The control unit that acts as the ‘stage manager’ and ensures all the components perform in concert.
What is memory?
A collection of cells, each with a unique physical address.
What is a memory cell?
A memory cell is the smallest part of a computer memory that can be changed in a single operation. A memory cell records a number written in binary - called its content. A memory cell has an identification number called its address.
A cell size varies from machine to machine, depending on i#the machines ‘accecability’. Modern day machines are normally 1 byte.
What is the ALU?
Arithmetic/Logic unit can perform basic arithmetic and logic operations on data such as addition, subtraction, multiplication and division, as well as logic operations such as AND, OR and NOT.
The ALU operates on words, a natural unit of data associated with different system designs
What is a word?
This is the number of bits processed by a computer at once.
What is a register?
A small memory location that holds usually one word, and are used to hold data that are going to be accessed again immediately. access to a register is much faster that access to memory locations.
What is an input device?
What is an output device?
Input unit: a device through which data or prgrams from the outside world is entered into the computer.
Output Unit: A device in which records stored on the computer are made available to the outside world.
What is the control unit?
The organizing driving force in the computer, and is in charge of the fetch-execute cycle. It tells memory, ALU, i/o devices how to respond to instructions they have been sent.
what registers are in the Control Unit?
Instruction register (IR): Contains the instruction that is currently being executed.
Prgram Counter (PC): contains the address of the next instruction to be executed.
What is addressability?
The number of bits stored in each addressable location in memory.
What is the CPU?
The central processing unit made of a combination of the ALU and the control unit. it can be thought of as the ‘brain’ f the computer that interprets and executes instructions.
What are the three buses?
Address bus: Used to select the memory location or hardware devce which data will go or be taken. This bus is unidirectional as data only goes from the CPU to memory.
Data bus: allows data to flow between the CPU, memory and I/O devices. it is bidirectional as data can flow both ways, to and from the CPU.
Control Bus: manages the flow of the control signals from the CPU. used to generate timing and control signals to control all the associated peripherals, microprocessor uses control bus to process data. it is a unidirectional bus.
What is bus width?
The number of bits that can be transferd simultaneously - the wider the bus width the more data that can be transferd.
what is Cache memory ?
A type of small high speed memory used to hold frequently accessed data. before a main memory access the CPU checks if the data is stored in cache or not.
What is pipelinning?
A technique used to speed up the fetch-execute cycle by breaking down instructions into smaller instructions that can be overlapped.
What is the motherboard?
The main printed circuit board of a personal computer that has ports for attaching other components to the bus.
What is RAM?
Random Access Memory is a type of memory in which each cell can be directly accessed and changed.
RAM is volatile, so it does not retain its bit configurations once power is lost.
What is ROM?
Read Only Memory stroes data that can not be changed. Placing the bit pattern in ROM is known as burning, and once done the bit pattern can not change, and is done during either the manufacture of the computer or at the assembly of all the components.
instructions that the computer needs to start itself. Frequently used software is also stored in ROM so the system does not have to read the software each time the computer is turned on.
What is the differnce between RAM and ROM
RAM bit patterns can be directly accessed and changed, but ROM has permanent bit patterns that can not be changed.
RAM is volatile memory meaning when power is lost it does not retain its bit patters, but ROM does. As the bit patterns in ROM can not be lost, it is used to store the instructions that the computer needs to start itself. Frequently used software is also stored in ROM so the system does not have to read the software each time the computer is turned on.
Why are Secondary storage devices necessary?
What are secondary storage devices?
Most of a computers memory is volatile, meaning it will not retain data once power is lost. Therefore it is essential that a computer has other types of storage. These devices are known as secondary storage devices, or auxiliary storage devices which are both input and output devices.
What is the flash drive?
Replaced floppy disks
. non volatile and can be re-written.
.The device is fitted intergrated with a USB
. used to build SSD, and SSD has no moving parts so is much faster then hard disk. However it can eventually wear out , so can fail just as a hard disk can.
What is a touch screen and what are the four types?
A computer monitor that can respond to the user,
touching the screen with a stylus or finger. it is both an input and an output device. A touch screen will register not only hat it is being touched, but where abouts it is being touched.
There are four types
– Resistive
– Capacitive
– Infrared
– Surface acoustic wave (SAW)
How does a resistive touch screen work?
A screen made up of two layers of electrically
conductive material
– One layer has vertical lines, the other has horizontal
lines
– When the top layer is pressed, it comes in contact
with the second layer which allows electrical current
to flow
– The specific vertical and horizontal lines that make
contact dictate the location on the screen that was
touched
How does a capacitive touch screen work?
Capacitive touch screen
A screen made up of a laminate applied over a
glass screen
– Laminate conducts electricity in all directions; a very
small current is applied equally on the four corners
– When the screen is touched, current flows to the
finger or stylus
– The location of the touch on the screen is determined
by comparing how strong the flow of electricity is from
each corner
How does an infered touch screen work?
Infrared touch screen
A screen with crisscrossing horizontal and vertical
beams of infrared light
– Sensors on opposite sides of the screen detect the
beams
– When the user breaks the beams by touching the
screen, the location of the break can be determined
How does surface accoustic touch screens work?
Surface acoustic wave (SAW)
A screen with crisscrossing high frequency
sound waves across the horizontal and
vertical axes
– When a finger touches the surface,
corresponding sensors detect the interruption
and determine location of the touch
What are embedded systems?
Computers that are dedicated to perform
a narrow range of functions as part of a
larger system.
Typically embedded systems are housed on a single microchip with the programs stored in ROM.
.All appliances that have a digital interface (watch, microwaves etc), utilize embedded systems.
the term pretty much encompasses everything except desktop PC’s.
What are the four types of parallel processing?
- Bit-level parallelism
- Instruction-level parallelism
- Data-level parallelism or synchronous processing
- Task-level parallelism
What is synchronous processors?
Multiple proccessors apply the same program i lock-step to multiple data sets.
What types of touch screen would a gloved hand work with and why?
It could be used with resistive, infrared and SAW but could nit be used on capasitive which rely on current flowing to the point.
what is a shared parallel processor?
The situation in which processors share global memory.
What is Bit-level parallelism
Bit-level parallelism
– Bits can be processed simultaneously
– Ex: Increasing word size so that it reduced the number of operations required.
What is Instruction-level parallelism
•Instruction-level parallelism
– Instructions can be executed simultaneously
– Ex: Pipelining (overlapping instructions)
– Ex: Superscalar (multiple execution units). note this is not multiple processing units, but does have multiple execution resources.
What is Data-level parallelism
• Data-level parallelism or synchronous processing
– Data subjected to same operation sequence simultaneously
– Ex: Calculation of all student’s GPAs simultaneously
What is Task-level parallelism
•Task-level parallelism
– Entire tasks can be completed simultaneously
– Ex: Google servers – simultaneous independent searches
– Ex: “Pipelined” processors
What is the magnetic tape?
What was its biggest floor?
The first truly mass auxiliary storage device was the magnetic tape drive. It is commonly used to make a backup of data on a disk.
They have one serious drawback: to access data in the middle of the tape, all the preceding data must be accessed and discarded, and the tape would have to physically move through the read/write head which is time consuming.
What is a magnetic disk?
Cross between a tape recorder and a compact disk player.
There is a read/write head that travels across the spinning magnetic disk retrieving or recording data, and data can be directly accessed unlike the magnetic tape.
The surface of the disk is split into tracks and sectors. Tracks are concentric circles around the surface of the disk, and are divided into sectors. Blocks are the information contained within each sector. The location of the tracks and sectors are marked magnetically when the disk is formatted; not physically.
An input/output instruction specifies the track and sector. When the read/write head is over the appropriate track, it waits until the appropriate sector is underneath it. It then accesses the blocks information.
What is seek time, latency, access time and Transfer rate?
Seek time: Time for read/write head to be over right track
Latency: Time for sector to be in position
Access time: The time it takes a block to start being read. This is the sum of the seek time and the latency.
Transfer rate: Rate at which data moves from the disk to memory
What are the types of magnetic disks?
The outdated version was the floppy disk which is about 3” and capable of holding around 1.44MB of data.
The second type is the hard disk. This is actually comprised of multiple magnetic disks one underneath each other with a spindle going through them that rotates. A cylinder is the name given too all of the concentric tracks that lineup one under each other on all surfaces.
What is a CD and what are the different types?
A compact disk that uses a laser to read information stored optically on
a plastic-coated disk; data is evenly distributed around spiral track
CD-ROM read-only memory
CD-DA digital audio
CD-WORM write once, read many
RW or RAM both read from and written to
What is a DVD?
What is a DVD-DL?
What is blue-ray?
DVD: Digital Versatile Disk, used for storing audio and video.
DVD-DL: Duel layer, which nearly doubles the capacity of the DVD.
Blu-ray: Higher capacity DVD allowing higher resolution video, etc.
What are the names of the power to 10
-12 picca
-9 nanno
-6 Micro
-3 mili
3 Kilo
6 Mega
9 Giga
12 Tera
15 Peta
