1. Describe the memory hierarchy in the computer system. Why configure hierarchical storage?
The storage hierarchy in the computer system can be divided into three levels: cache memory, main memory, and auxiliary memory.
Cache memory is used to improve the speed matching between main memory and central processing unit. Used to expand storage space, that is, hard disks, optical discs, etc., with large capacity but slow access to data. The computer first puts the things to be read in the auxiliary storage into the main storage for processing, and then writes it back according to the situation.
The main memory is the internal memory, and the power failure information is lost, but when accessing the data block, its capacity directly affects the computer’s operating speed. Due to storage speed, various types of storage cost problems, and storage capacity problems, computers have built-in high-speed Cache (the fastest and most expensive) in the CPU, memory (fast and expensive), and hard disk (cheap and large capacity). The main storage method, while optical discs and flash memory are convenient removable storage media
and the configuration of hierarchical storage is to improve the efficiency of the system. Because the speed of the CPU is extremely fast, but the CPU needs the data in the memory when executing, but the speed of the memory is far behind the speed of the CPU, causing the CPU to wait for the memory, which seriously affects the efficiency of the CPU, so we must add cache To solve this problem, the data access speed of the cache is much faster than that of the memory.
2. Briefly describe the different compiling, linking, loading and address positioning processes.
Compilation: The source program is processed by the compiler or assembler to generate the target module. A program can be composed of multiple source program modules written independently and with different functions. Each target module is accompanied by an internal symbol table and an external symbol table for reference.
Link: The link program is based on the target module The call and dependency relationship between the main calling module, the called module and the library functions used are assembled and linked into a complete loadable executable module, which can be divided into the following three modes: static link, dynamic link, and run Time linking
Loading: The loader is to load the executable program into the memory. There are three ways: absolute loading, relocatable loading, dynamic runtime loading
Address positioning: available The process of converting the logical address of the execution program into a physical address is called address relocation, address mapping, or address conversion. It can be divided into three types of address relocation: static address relocation, dynamic address relocation, and runtime link address relocation
3. What is a logical address and a physical address? What is static address relocation and dynamic address relocation?
Logical address: The so-called logical address refers to the location of the disk given by the logical block number of the data (l block = 512 words l word = 64 bits) and the physical address is determined by the cylinder, The address determined by the physical location of the header, segment, etc.
Physical address: In the physical transmission process at the bottom of the network, the host is identified by the physical address
4. What are the disadvantages of fixed partition management? ?
- Previously divide the user area in the memory into a number of fixed partitions.
- The partition size is fixed in advance.
- The number and location of partitions are predetermined.
- The remaining memory in the partition is vacant, causing waste.
5. Briefly describe the difference between fixed partition storage management and variable partition storage management
Variable partition storage management does not pre-divide the user area in the memory into several Fixed partition, but when the job is required to be loaded into the memory, it is determined whether to allocate a partition for the job according to the size of the user’s job and the current memory space usage. Therefore, the partition size is not fixed in advance, but is divided according to the job demand; the number and location of the partitions are not predetermined. It effectively overcomes the waste problem caused by the vacant remaining memory in the partition in the fixed partition mode.