What Is Immediate Mode?
real-time mode
Real-time mode
Right!
- Chinese name
- Real-time mode
- Foreign name
- real-time mode
- Addressing
- Segment address + offset address
- Offset space
- 2 ^ 16 = 64KB
- real-time mode
- 8086 and 8088 can only work in real mode, while 80286 and above processors can work in real mode or protected mode.
- Real-mode operation only allows the microprocessor to address the first 1MB of memory space, from 00000H to FFFFFH. Memory addressing in real mode is the segment address + offset address. For example, the content of the segment register is 1000H, then he addresses the segment starting at 10000H, and the offset size is from 0000H-FFFFH, that is, the space size of the offset is 2 ^ 16 = 64KB
- Protected mode allows access to the first 1MB and above. When accessing the memory space of the extended area in protected mode, the offset address is still used. But the segment address is no longer provided by the segment register as in real mode. The segment register that originally placed the segment address contained a selector for selecting a descriptor in the descriptor table. Descriptors describe the location, length, and access rights of memory segments. The selector can select one of the 8192 descriptors from the global descriptor or local descriptor table. So at any time, the application has at most 8192 × 2 descriptors available.