Loader : Whenever we give the command to execute a particular program, the loader comes into work. The loader will load the. Skip to content. Change Language. Related Articles. Table of Contents. Improve Article. Save Article. Like Article. CPU Registers. We provide nothing but the best curated videos and practice problems for our students. Check out the C Foundation Course and master the C language from basic to advanced level. Wait no more, start learning today!
The instruction pointer is automatically incremented to contain the address of the next instruction in memory. Steps 3 , 4 , and 5 are called an instruction fetch. Notice that steps 3 — 7 make up a cycle, the instruction execution cycle. It is shown graphically in Figure 8. We will give a very brief look at interrupts in Chapter 17 , but the details are beyond the scope of this book. For now, it is sufficient to understand that the wfi instruction stops the program execution cycle.
Actually, the ARM fetches two instructions at a time. But this is an implementation detail that helps speed up program execution. The logical flow of a program follows the instruction execution cycle shown in Figure 8. How do we get the instructions into memory? The instructions for a program are stored in a file on a storage device; for example, a disk, device memory, or an SD card. The computer system is controlled by an operating system. When you indicate to the operating system that you wish to execute a program, e.
The contents in the file remain unchanged. How do we create a file on the disk that contains the instructions? This is a multi-step process using several programs. The programs and the files that each create are:. An editor is used to create source files. Contains the current instruction being executed by the CPU The CPU will perform the operation indicated by the instruction code contained in the instruction register E.
The program counter is a register memory cell! This register contains the address location in memory of the next instruction after the CPU finishes executing the current instruction in the instruction register The value in the program counter will be increased after the CPU finishes executing one instruction. After executing an instruction , the CPU obtains "fetches" the next instruction at the address location given in the program counter The fetched instruction is stored in the instruction register in the CPU and the program counter is increased to point to the next instruction in the memory The fetched instruction stored in the instruction register is the executed the CPU will do the operation indicated by the instruction code in the instruction register.
Supposed the CPU has just finished executing the instruction instruction code 0 in the instruction register :.
0コメント