Register: temporary storage of data and instructions

Controller: Control the reading of data and instructions in the register

Clock: program timing

Operator: operates on the data read from the register

Registers can only handle machine language

Register 1: Program Counter

Register 2: Flag register

This is achieved by setting the value of the program counter to the storage address of the function.

Use the base register to store the array contents and the index register to store the array index.

Conversion method between binary and decimal: Add the results of the powers of the binary bits to get the decimal number

The operation of decimal numbers in the computer is still converted into binary numbers for calculation: for example, shifting the binary number to the left by one position is equivalent to multiplying the number by 2.

Subtraction inside the computer is implemented using addition, here we use "complement"

Unsigned types are binary numbers that are all positive numbers. The signed type takes away the highest bit to represent the sign, leaving only n-1 bits, so the positive and negative values ​​account for half.

The difference between logical right shift and arithmetic right shift

Anything with 0x at the beginning represents the hexadecimal value.

Single precision floating point number (32 bits)

Double precision floating point number (64 bits)

The EXCESS system behaves in such a way that negative numbers do not need to be represented by a sign by setting the middle value of the range represented by the exponent part to 0.

There are 8 data signal pins, so it can represent 8 bits and 1 byte

There are 10 address signal pins, which can represent 1024 signals, which is 1K

Different data types, even the same value, occupy different memory sizes (therefore, in order not to waste the 8 bits of each layer when defining variable types in the program, you need to adjust the position of the types to be as compact as possible. using memory)

A pointer is also a variable. What it represents is not the value of the data, but the address of the memory where the data is stored. By using a pointer, you can read and write data at any specified address.

Stored at consecutive addresses in memory. Use index to indicate the address of each data.

Stacks and queues do not use indexes to access data, but they can divide a memory area in the form of an array with a certain number of elements to implement internal access.

Stack: first in, last out

Queue: first in, first out (using a ring buffer, which can be accessed repeatedly in a fixed size memory)

It can be more convenient to add, delete, modify and check

Easy to search

Share DLL files to reduce duplicate storage of functions

Reduce program file size by calling _stdcall

There are restrictions. If the proportion of repeated content in the file is not large, it will cause the file to expand.

The key to the Huffman algorithm is that "data that appears multiple times can be represented by a number of bytes less than 8 bits, and data that is rarely used can be represented by a number of bytes exceeding 8 bits."

Use a Huffman tree to arrange the codes of each character, with high frequency in the short bit and low frequency in the long bit, and each code is used as a leaf node of the binary tree

Source code->Native code->Run

Windows overcomes hardware differences other than CPU, allowing different models to be compatible with the same program

Different CPUs use different machine languages. Therefore, when the same program is migrated to other CPUs, a CPU-specific native code compiler is required to recompile it into the corresponding native code.

Use virtual machines to obtain other operating system environments

Java virtual machine

BIOS

The essence of native code is a sequence of hexadecimal values

The compiler is responsible for translating source code into native code

The .c file becomes an .obj file after being compiled by the compiler. At this time, the program still cannot run.

The connector splices multiple target files together to generate an EXE file. This process is called linking. Only after entering the link command can the .exe file be generated.

Library files are packaged from multiple object files. By specifying a library file when linking, the linker can extract the required object files from it and link them with other object files to generate an EXE file.

Windows API is a program application interface

A library file that contains the target file itself and can be directly linked to the EXE file is called a static link library.

In the EXE file, the memory addresses allocated to variables and functions are virtual. When the program runs, these virtual memory addresses will be converted into actual memory addresses. The linker will record various locations that require memory address translation at the beginning of the EXE file. This information is called relocation information.

The stack is used to store local variables in functions and parameters that need to be passed.

The heap is used to store arbitrary data

It is a monitoring program with the function of loading and running programs.

High-level programming languages ​​use a common language when editing source code, but after compiling native code in different operating systems, the program calls system functions within the system. This is portability.

Operating systems and high-level programming languages ​​abstract the hardware so that programmers no longer have to worry about system calls and hardware

Available in 32-bit and 64-bit versions

Provide system calls through a set of API functions

Using GUI

Ability to print output in WYSIWYG format

Provide multi-tasking capabilities

Provide network and database functions

Automatic device driver installation via Plug and Play

Assembly language uses mnemonics, which are instructions for native code

Source code written in assembly language must be converted into native machine code before it can be run.

The program that converts assembly language into native code is an assembler, and the conversion process is called assembly

You can also convert native language into assembly language. The conversion process is called disassembly.

The C language compiler can also convert C language source code into assembly language source code

There are two types of instructions in assembly language

In assembly language, comments starting with # sign are

grammar

When running the program, a stack space will be opened in the register. The function variables called will use this stack. The stack space will be cleared after the program ends.

Call functions

variable

cycle

conditional branch

Input and output instructions

I/O controller = port

Interrupt handling

DMA

PIO

Store the data in the video memory and display it on the monitor

The graphics card has independent video memory and image processor GPU

Programmers only write programs for learning. The content of this program is to let the computer read a large amount of data, then learn the characteristics of this data, and generate a recognition model

Supervised learning is to provide the computer with a large amount of data with correct answers.

step

Support Vector Machines

Python language

Cross-validation is a method of performing machine learning that continuously rotates training and test data

You can check whether the recognition rate of the learning model is biased due to the type of learning data.