A character is a byte, which is eight.
Each process has the PCB, the program and data segments, the code is translated into the program instructions, CPU will find the corresponding physical address according to the request command, followed by calculation.
Logical addresses are compiled.
Relative address ----> logical address, the absolute address ----> physical address
Compile: compile into a number of object modules and then linked, form a complete load module, and then loaded into memory by the loader.
Links: static linking (to connect), dynamic link (when dynamic loading in turn link) is loaded, run-time dynamic linking (when the needs of the target module during program execution only link, easy to modify and update, to achieve module shared).
Load way:
Absolute load:
Procedure only applies to a single channel, only one program, the program can be determined loading position. Compile time to produce the final loading position.
: One-time into memory when the memory is not enough free address can not be loaded into memory. When the load can not be modified, nor can apply for space. The initial address is 80, agreed to +100 operation, so static relocation.
Fragmentation :( paging storage and there go into detail) using a relocation register is the address into the real time execution of the postponed until the transformation of the physical address. Dynamic relocation may allow movement program in memory.
-------------------------------------------------- ----- "memory space allocation" --------------------------------------- ----------
Memory space allocation and recovery
Virtuality, the operating system provides some kind of technology to expand the memory space logically.
The operating system provides the address conversion function, responsible for transforming the logical address and the physical address of the program.
The operating system provides memory protection, interfere with each other:
1. The design of the upper and lower limit on the register, storage process, to see if cross-border
2. Using the relocation register (base register), and a line address register (register indefinite length). Boundary address storage process maximum logical address, redirection register holds the starting address to see 80+ redirect the starting address is not more than the sector address register.
Covering technology: memory size exceeds the sum settlement procedures.
