Lecture 16: Processes Intro to IT COSC1078 Introduction to Information Technology Lecture 16 Processes James Harland

Lecture 15: BootingIntro to IT Introduction James Harland URL: Phone: Office: Consultation: Mon , Thu What colour is my office door? Carpet? Chair?

Lecture 16: ProcessesIntro to IT Introduction to IT 1 Introduction 2 Images 3 Audio 4 Video WebLearnTest 1 5 Binary Representation Assignment 1 6 Data Storage 7 Machine Processing 8 Operating Systems WebLearn Test 2 9 Processes Assignment 2 10 Internet 11 Internet Security WebLearn Test 3 12 Future of ITAssignment 3, Peer and Self Assessment

Lecture 16: ProcessesIntro to IT Overview  Questions?  Assignment 2  Assignment 3  Processes  Questions?

Lecture 16: ProcessesIntro to IT Processes

Lecture 16: ProcessesIntro to IT Processes A program is a static set of instructions A processes is the execution of a program, which changes state over time.

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register CC ROM RAM ProcessorMemory Disk 00 CC

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register DD ROM RAM ProcessorMemory Disk 00 CC DD

Lecture 16: ProcessesIntro to IT Processes Switching Ready Waiting Scheduler maintains process table

Lecture 16: ProcessesIntro to IT Processes Switching

Lecture 16: ProcessesIntro to IT Interrupts  Signals to the CPU  Often generated by timing circuits  CPU reacts by jumping to appropriate memory location  Dispatcher  selects a ready process  resets timing circuit  starts process  CPUs often designed to switch process states efficiently

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register 11 ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register FF ROM RAM Processor Memory Disk 00 FF

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register FF ROM RAM Processor Memory Disk 00 FF

Lecture 16: ProcessesIntro to IT Processes Executing in Context Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT ``Thomas, you wouldn’t! Naughty!’’ Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT ``Thomas, you wouldn’t! Naughty!’’ Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT ``Thomas, you wouldn’t! Naughty!’’ Program Counter Instruction Register BB ROM RAM Processor Memory Disk 00 BB

Lecture 16: ProcessesIntro to IT Software  `Programs should be able to do anything!’ (???)  Programs should be able to do anything reasonable  What is reasonable?  Not changing OS, not deleting other processes from memory, not playing with other people’s things, …

Lecture 16: ProcessesIntro to IT Interrupts  Provide mechanism to switch processes  CPU doesn’t have to wait for I/O transfers  Switching leads to faster throughput  `Save document’ means CPU does something else while the save takes place

Lecture 16: ProcessesIntro to IT Conclusion  Work on Assignment 2 (and 3?)  Web Quizzes and Web Test 2  Finish reading book!