8. 1 Background ●●● ●●●● ●●●●● ●●●● Binding of instructions and data to memory ●●0●● ●●●● ●●●● addresses can happen at three different stages ● Compile time If memory location known at compile time, absolute code can be generated must recompile code if starting location changes E.g. The MS-DOS. COM-format programs Load time +linkage time) If memory location is not known at com pile time Must generate re-locatable code if memory location is known at load time, absolute code can be generated at this time if starting location changes, only need reload the code12 8.1 Background ⚫ Binding of instructions and data to memory addresses can happen at three different stages ⚫ Compile time ▪ If memory location known at compile time, absolute code can be generated ▪ must recompile code if starting location changes ▪ E.g. The MS-DOS .COM-format programs ⚫ Load time （+linkage time） ▪ If memory location is not known at compile time, Must generate re-locatable code ▪ if memory location is known at load time, absolute code can be generated at this time ▪ if starting location changes, only need reload the code