Computing unit + controller = CPU, CUP + memory = host, I/O devices are external devices
The main memory consists of many storage units , each storage unit includes multiple storage cells , each storage cell stores a binary code (0 or 1)
A memory cell can store a string of binary codes, which are memory words
The number of bits of this code is called the storage word
Many storage units together form a storage body
Although the address register MAR and the data register MDR are part of the memory, they exist in the CPU in modern computers .
Byte addressable no relationship and data lines (only when word-address before considering the data lines, the data lines is determined by the word length), and only the address lines related
When encoding by byte, a word may occupy several memory cells, and the word address is the minimum value among the addresses of these consecutive memory cells.
Data register bits to and stored word length equal
The arithmetic unit includes general registers (ACC, MQ, X, LX, BR) for temporary storage of operands and intermediate results. Program status word register , which retains the status information of various instructions to prove the operating status of the system
The controller is composed of a program counter PC, an instruction register IR, and a control unit CU
The computer is composed of arithmetic unit, memory, controller, input device and output device (features of von Neumann computer)
Instructions and data are stored in the memory with the same status , and the memory can be accessed by address (Von Neumann computer characteristics)
Instructions and data are expressed in binary code (Von Neumann computer characteristics)
Instructions are composed of opcode and address code . Opcode: the nature of the operation, address code: the location of the operand in the memory (characteristics of von Neumann computers)
Instructions are stored in order in the memory , and specific conditions can be changed (Von Neumann computer characteristics)
The machine is centered on the arithmetic unit , and the data transmission between the input and output devices and the memory is completed through the arithmetic unit (characteristics of von Neumann computer)
The biggest difference between a compiler and an interpreter is that the former generates object code, while the latter does not.
The working process of the computer is to constantly fetch instructions from the memory one by one, and then send them to the controller . After analysis, the CPU issues various operating commands to direct each component to complete various operations until the execution of the instructions in the program ends.
2. Computer performance indicators
1. Summary of knowledge points
Throughput refers to the rate at which information flows into, processed and out of the system
The corresponding time refers to the time from when the job is submitted to when the job gets the CPU response
The main frequency is the frequency of the main clock inside the machine, and is an important parameter to measure the speed of the machine
The CPU cycle is also called the machine cycle. It is usually defined by the shortest time to read an instruction word from the memory. An instruction cycle usually consists of several CPU cycles.
The CPU clock cycle is the smallest unit in the CPU, the reciprocal of the main frequency
The number of clock cycles required for CPI to execute an instruction
MIPS can execute millions of instructions per second
The number of floating point operations that FLPOS can perform per second (MLPOS: million GLPOS: billion TLPOS: trillion PLPOS: peta billion)
IPC refers to the number of instructions executed in each clock cycle of the CPU
CPU execution time refers to the execution time of the CPU for a specific program