8 chapter 1 introduction io write copy a byte or a

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: the contents of two registers to the ALU, which adds the two words together and stores the result in a register, overwriting the previous contents of that register. I/O Read: Copy a byte or a word from an I/O device into a register. PC is also a commonly-used acronym for “Personal Computer”. However, the distinction between the two is always clear from the context. 8 CHAPTER 1. INTRODUCTION ¯ ¯ I/O Write: Copy a byte or a word from a register to an I/O device. Jump: Extract a word from the instruction itself and copy that word into the program counter (PC), overwriting the previous value of the PC. Chapter 4 has much more to say about how processors work. 1.4.2 Running the hello Program Given this simple view of a system’s hardware organization and operation, we can begin to understand what happens when we run our example program. We must omit a lot of details here that will be filled in later, but for now we will be content with the big picture. Initially, the shell program is executing its instructions, waiting for us to type a command. As we type the char...
View Full Document

This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

Ask a homework question - tutors are online