Chapter II knows CPU
2.1 8-bit processor review Intel 8080 consists of more than 6,000 transistors, and approximately 600,000 operations can be performed per second. The addressing space reaches 64KB, and the directive is more than 60 or more. Apple II uses a 6502 chip, there is a fixed stack area of 256Byte, with some basic functions. Unfortunately, it has no subsequent compatibility products.
2.2 16-bit microprocessor 2.2.1 Composition Structure 8086/8088 and 6502 The largest difference between the instructions in the architecture. 8086 Introduces the concept of the pipeline when executed. 2.2.4 Terminal processing The terminal is considered to be a function of a function, but this function may be called at any time. The time to cause this operation is called the source. The interruption number is actually an entry address of the interrupt processing.
2.3 32 Bit Microprocessor 2.3.1 Register Composition In 80386, 8 32-bit universal registers can be used as a pointer register. In the protection mode, the memory logical address distribution is generally through the visible partial register points to an invisible memory portion. 2.3.2 Protection Mode Protection Modes The most important thing is to improve the multitasking mechanism. (1) There is no protection between tasks: By putting each different task in different virtual address spaces, isolation between unless the task is implemented. (2) Protection of the same task: 4 protection levels are defined within each task (0: Supreme Permissions, 3: Minimum Permissions). The general system uses only two levels (such as Windows) using ring 0 and ring 3. 2.3.3 80386 Addressing mode 80386 Continue to use segmented methods to manage the main memory. The logical address of the memory is represented by a segment base address (start address of the segment) and within the segment; the address of the memory cell is obtained by the segment base address plus segment offset. In the protection mode, the segment base address can be 32 bits, and there is no need to be a multiple of 16, which may be any start point in the memory, and the maximum length of the segment is up to 4GB. In the 8086/8088 and 80386 real mode, the segment register is used to represent the segment value. In the protection mode of 80386, the segment register becomes the selection. The role of the selector is to point to the corresponding descriptor (used to describe the attribute parameters of the segment). The external terminal is called "interrupt", and the internal interrupt is called "abnormal". Interrupt handler is divided into two: (1) When the program is interrupted, the interrupt itself is processed, and the program runs to the interrupt point and continue. (2) Interrupt procedures may be processed in the ring 1, and then the rip ring 2 performs some processing, and it is possible to skip the user layer (ring 3) for processing. However, there is no process of ring 1, ring 2 in Windows, so this is generally in an abnormality.
