What constitutes a system in terms of hardware?

1. What constitutes a system in terms of hardware? • Processor(s) • Memory (Cache, Main, Secondary) • I/O Devices • Network Interfaces

2. What is an Operating System? • Extended Machine (Virtual machine) –Top Down View • Machine Language to access devices • OS provides abstraction

3. What is an Operating System? cont. • Resource Manager – Bottom-Up View • Many resources to be shared – memory, processor, I/O • Resources shared – Time and Space • Time – CPU, Shared Devices • Space (Part of the whole) – Memory

4. Brief History of Operating Systems • Babbage Analytical Engine • First Generation – Strictly used machine language on plug-boards and later punch cards.

5. Brief History of Operating Systems cont. • Second Generation – Transistor was introduced along with batch systems • A collection of jobs (programs) were collected • Ran through card reader • Placed on tape • Another computer did the actual computations • Output tape generated • Output printed IBM 7094

6. Brief History of Operating Systems cont. • Third Generation – Integrated Circuits and Multiprogramming • IC – lots of transistors on a single chip, faster processors • Multiprogramming – reduction of idle CPU time • Timesharing – Everyone gets a time slice of the CPU pie. IBM 360

7. Brief History of Operating Systems cont. • Fourth Generation – Microcomputer aka PC • Evolution from DOS to Windows Vista • UNIX – Linux

8. Technology Trickle-Down Effect • High-Level Languages • Multitasking • Peripheral Devices Mainframes->Minicomputer->PC->Embedded Systems

9. Different OSs for different systems • Mainframe – processing many jobs at once where the OS must be able to handle a tremendous amount of I/O • Server – Serve multiple users at once over a network to share hardware and software resources. • Multiprocessor – Must efficiently and effectively coordinate the load among several processors.

10. Different OSs for different systems cont. • PC – Providing varying services to a single user. • Real-Time – Must provide responses to input within a guaranteed time. Often used in embedded systems. • Embedded Systems – Often use soft RTOSs and have resource limitations such as memory, size, and power consumption.

11. Review of Computer Hardware • Processors • Fetch->Decode->Execute->Memory • Registers – General, PC, SP, Status and Control • kernel and user mode – use of system calls • Kernel – execute any instruction/full access to hardware • User – restricted use involving I/O and memory instructions

12. Review of Computer Hardware cont. • Memory • Memory Hierarchy • Type of ROM memory (EEPROM, Flash) • Magnetic Disk (Platter, Cylinder, Track, Sector) • Holding Multiple programs in memory introduces two problems • How to protect the programs from one another and the kernel from them all. • How to handle relocation.

13. Review of Computer Hardware cont. • I/O Devices • Controllers and Devices • Device driver • Polled (Busy Waiting) • Interrupt • DMA – (Memory <-> Device) bypass CPU

14. Review of Computer Hardware cont. • Buses (Faster I/O and CPU to memory traffic) • Many buses: ISA, PCI, SCSI, IDE, Memory, Local • Plug and Play • BIOS • POST • Check how much Memory • Checks which devices are installed • Locates Boot device and loads OS into memory