The second week study concluded
this week we taught himself computer Introduction fourth and fifth chapters of content, four, five chapters introduce us to the knowledge about computer hardware layer, through these chapters to learn I learned something about gates and circuits and knowledge member calculations.
/ Chapter IV gate and circuit /
Circuit: the gate circuit is a combination of interrelated, for implementing the specified logical functions.
Circuit on the door and I also learned three different representations:
1. Boolean algebra: it is an algebraic calculation by the British mathematician Boolean invention, its expression is an excellent way to demonstrate the circuit activity.
2. A logic diagram: it is the graphic representation of the circuit. Each type of door by a specific graphical symbols.
3. The truth table: It lists all combinations of inputs and corresponding outputs A door may be encountered, so that comprehensive and specific definition of such a door function.
door:
1. NAND: NAND gate called an inverter, inverting the value it would have entered.
2. The AND gate: two input signals when an output of the same is 1, otherwise the output is 0.
3. OR gate: If the two input values are 0 then the output value is 0, and 1 otherwise.
4. XOR gate: If the same two inputs, the output is 0, or 1 as an output.
The NAND and NOR gates: NAND and NOR gates are AND gates and OR gates opposition door.
Door handle Review:
If the two input values are 1, 1 and to generate the goalkeeper.
If an input value is 1, input values are one or two, or generate a goalkeeper.
If only one input value is 1, instead of two, to generate an exclusive OR gate.
The results generated with NAND gates and an AND gate to generate the opposite.
Contrast to the results and the results of the OR gate generates a NOR gate generated
How to construct the door:?
Transistor: a resistor wire or a device, its role is determined by the level of the input signal. Transistor has three terminals, i.e. the source, base and emitter.
Semiconductor: neither good conductors nor an insulator material, such as silicon.
Circuit: circuit may be divided into two categories, one is called combination circuit, and the other is called a sequential circuit.
Combining circuit: the output circuit is only determined by the value of input values.
Timing circuit: the output circuit is a function of the input value and the current state of the circuit.
(Where there is a concept called equivalent circuit: the output value corresponding to each combination of inputs, generates two identical output circuits.)
Boolean algebra distributive law: A (B + C) = AB + AC
Properties or
commutative: AB = BA A + B = B + A
distributive property: (AB) C = A ( BC) (A + B) + C = A + (B + C)
the identity: A1 = A A + 0 = A
complement: A (A ') = 0 A + (A') = 1
de Morgan's law: (AB) '= A'ORB' (A + B) '= A'B'
Adder
An adder (adder): an addition operation circuit for performing a binary value.
Half adder (half adder): two-digit calculating circuit and the right and generates a carry.
Full adder (full adder): calculated two-digit and, taking into account the carry input of the circuit.
Multiplexer
A multiplexer (multiplexer): using some input control circuit outputs the transmission signal determining which of the signals with the input data lines.
Demultiplexer circuit is to perform the opposite operation. That is, it has only one input, the value of n in accordance with the control lines, the value of the input signal will be sent to output 2 ^ n.
The memory circuit
integrated circuit
IC: also known as chips, is embedded in a silicon wafer of a plurality of gates.
- SSI (small scale integration): 1 to 10 doors
- MSI (medium scale integration): 10 to 100 doors
- LSI (Large Scale Integration): 100 to 100,000 gates
- VLSI (very large scale integration): more than 100,000 doors
CPU chip
CPU is a high level circuit having an input line and an output line.
/ Chapter calculation means /
Member separate computer
processor, a display, an image processor, a camera, a random access storage, a hard drive, DVD drive, etc.
Stored program concept
Logical consistency instruction 1944 to 1945 for data and operational data, and they can be stored together, which is a major point defined on the history of computing. This principle is known as the von Neumann architecture, computer design based on this principle is still the basis of the current computer.
Von Neumann architecture
component:
Memory cells store data and instructions
for an arithmetic logic unit data performs arithmetic and logical operations
to transfer data from the outside world to an input unit of the computer of
the results from an internal computer to the outside world, the output unit
act as stage manager to ensure that the other components are involved in the control unit performance
RAM
Memory is a collection of memory cells, each memory cell has a unique memory address.
Addressability: in each addressable memory location to store the number of bits of the address.
An arithmetic logic unit
An arithmetic logic unit: a computer means for performing an arithmetic operation (addition, subtraction, multiplication, and division), and logic operations (compare two values) of.
Registers: CPU in a small storage area for storing intermediate data or special values.
Input / output unit
The input unit: receiving data to be stored in memory devices is to make the external data and programs entered into the computer of a computer.
Modern input device comprises a scanning device keyboard, a mouse and supermarkets use.
The output unit: an apparatus for storing the data in memory is displayed or printed, or made of a permanent copy of the information stored in the memory or other devices, the result is that the outside world on the computer using the storage device .
The most common output device is a printer and a display.
The control unit
the control unit: controlling the operation of the other components, thereby performing other instructions in the register.
Instruction register: to store the instruction currently being executed register.
Program Counter: register address of the next instruction to be executed is stored.
CPU: a combination of an arithmetic logic unit and a control unit, a computer that interprets and executes instructions of the "brain."
Bus width: the number of bits transmitted in parallel on the bus.
Cache: storing frequently used data for a small high-speed memory.
Pipeline: A small step instruction is decomposed into technical execution may overlap.
Board: a main circuit board of a personal computer.
Read - execution cycle
step:
Read the next instruction
Deciphering instruction
, if needed, obtain data
execution instruction
RAM and ROM
A RAM (Random Access Memory) is a memory cell for each (typically 1 byte) of the memory can be accessed directly.
Note: Access to the nature of each memory cell is rewritten this storage unit.
Content (Read Only Memory), a ROM can not be changed, is permanent, storing operation can not change them.
Note: The bit pattern is called burn-in ROM. Only during manufacture or assembly ROM computer to burn bit combinations.
Secondary storage device
Example:
Tape
disadvantages: If you want to access data in the middle of the disk, it must access all this data before the data and discard them.
Disk
disk drive is a mixture of a CD player and tape recorder.
Track: concentric disk surface.
Sector: an area of a track.
Block: the information stored in the sector.
Seek: positioning the head to a designated track time spent.
Waiting time: the time to the specified sector is positioned below the head takes.
Access time: time spent before the start of reading a block of data, i.e. seek time and wait time and.
Transfer rate: the rate of data transfer from disk to memory.
Cylinder: a collection of all the concentric tracks of the disk surface.
CD and DVD
Flash Memory
Flash memory is a writable non-volatile computer memory that can be erased.
Flash memory is used to make solid state disk (SSD), solid state drive can be directly substituted with a normal hard disk.
touch screen
It displays text and graphics in the same manner as conventional displays, in addition it can detect a user touch with a finger or stylus on the screen, and to respond.
The touch screen is not only a touch is detected, it can know the position of the touch screen.
Implement touch screen technology:
Resistive touch screen
capacitive touch screen,
infrared touch screen
surface acoustic wave (SAW) touchscreen
Embedded Systems
Parallel Architecture System
Parallel Computing
form:
Bit-
parallel bit-level is increasing the word length of the computer-based.
Instruction level
instruction level parallelism is based on some instruction in the program can be performed simultaneously and independently.
Data level
data-level parallelism simultaneously performed for different sets of data groups based on the same instruction set.
Sync: a plurality of multi-processor will be applied to data sets with a program.
Task-level
parallelism task level are based on different processors can perform different operations on the same or different data sets.
Shared Memory Parallel Processor: a plurality of processors sharing a case where the entire memory.
Parallel Hardware Category
Parallel hardware categories reflecting the different types of parallel computing. A plurality of independent multi-core processor core, which usually is a central processing (CPU). Superscalar processor can issue multiple instructions to the execution unit, while the multi-core processor can issue different instructions in different execution units. That is, each individual core can comprise a plurality of execution units.
Symmetric Multi-Processor (SMP) comprising a plurality of the same core. They shared memory, and is connected via a bus. A symmetric multiprocessor cores typically limited to less than 32. Distributed computer comprising a plurality of memory cells, which are connected via a network. Cluster is formed by a computer connected to the existing network by a set of independent machines. Such devices typically comprise more than one thousand processors.
Problem: the role and operation of the door of some of the rules are not clear enough memory, yet found more effective than rote memory method, while recognizing that chapter V back too plain, between the various system more difficult to understand concrete relationships and operating principles.
Summary: Through the fourth and fifth chapters of the study, I learned the knowledge of computer hardware, knowledge of this course has gradually grown to understand that they can see tangible part, so I initially learned this seemingly computer very complex and high-end components of the machine running the equipment and use the appropriate configuration, helping me on the one hand reflected in the deepened my understanding of the computer, it also made me really harvest in the daily life of this course the benefits, I can finally understand some salesman selling computers mouth of strange parameters and configuration. Finally, we hope to put it on their own hard-won interest in computers maintained, inexhaustible motive force for their future professional learning.
