operating system should be convenient to use, easy to learn, reliable, safe, and fast

operating system should be easy to design, implement, and maintain, as well as flexible, reliable, error-free, and efficient

The __________ is to run the entire operating system as a single program in kernel mode. The operating system is written as a collection of procedures, linked together into a single large executable binary program.

written to provide the most functionality in the least space. Although it has some structure, its interfaces and levels of functionality are not well separated

limited by hardware functionality, the original UNIX operating system had limited structuring.

The UNIX OS consists of two separable parts:

The operating system is divided into a number of layers (levels), each built on top of lower layers. The bottom layer (layer 0), is the hardware; the highest (layer N) is the user interface.

The basic idea behind the ____________ design is to achieve high reliability by splitting the operating system up into small, well-defined modules, only one of which—the microkernel—runs in kernel mode and the rest run as relatively powerless ordinary user processes.

Communication takes place between user modules using ___________

Many modern operating systems implement ________________

Overall, similar to layers but with more flexible. (Linux, Solaris)

Aqua UI plus Cocoa programming environment. Below is kernel consisting of Mach microkernel and BSD Unix parts, plus I/O kit and dynamically loadable modules (called kernel extensions)

Apple mobile OS for iPhone, iPad. Structured on Mac OS X, added functionality. Does not run OS X applications natively

Developed by Open Handset Alliance (mostly Google (Open Source). Similar stack to IOS and based on Linux kernel but modified

________ is finding and fixing errors, or bugs

___ generate log files containing error information

______________ can generate core dump file capturing memory of the process

_______________ can generate crash dump file containing kernel memory

Beyond crashes, ______________ can optimize system performance

“Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.”

Improve performance by removing bottlenecks

Programming interface to the services provided by the OS

If a process is running a user program in user mode and needs a system service, such as reading data from a file, it has to execute a ____________ to transfer control to the operating system.

The operating system then figures out what the calling process wants by inspecting the _________.

Then it carries out the system call and returns control to the instruction following the __________.

In a sense, making a system call is like making a special kind of ___________—only system calls enter the kernel and procedure calls do not.

Typically, a number associated with each system call ____________, which maintains a table indexed according to these numbers

_____________ methods do not limit the number or length of parameters being passed.

types of system calls

• end, abort  load, execute  get process attributes, set process attributes  wait for time  wait event, signal event  allocate and free memory  Dump memory if error  Debugger for determining bugs, single step execution  Locks for managing access to shared data between processes

 create file, delete file  open, close file  read, write, reposition  get and set file attributes

 request device, release device  read, write, reposition  get device attributes, set device attributes  logically attach or detach devices

 get time or date, set time or date  get system data, set system data  get and set process, file, or device attributes

 create, delete communication connection  send, receive messages if message passing model to host name or process name (From client to server)  Shared-memory model, create and gain access to memory regions  transfer status information  attach and detach remote devices

 Control access to resources  Get and set permissions  Allow and deny user access

___________ provide a convenient environment for program development and execution.

Provide a convenient environment for program development and execution

Create, delete, copy, rename, print, dump, list, and generally manipulate files and directories

Some ask the system for info - date, time, amount of available memory, disk space, number of users. Others provide detailed performance, logging, and debugging information

- used to store and retrieve configuration information

Text editors to create and modify files. Special commands to search contents of files or perform transformations of the text

Compilers, assemblers, debuggers and interpreters sometimes provided

Absolute loaders, relocatable loaders, linkage editors, and overlay-loaders, debugging systems for higher-level and machine language

Provide the mechanism for creating virtual connections among processes, users, and computer systems.

Launch at boot time (Some for system startup, then terminate and some from system boot to shutdown). Provide facilities like disk checking, process scheduling, error logging, printing

o Don’t pertain to system o Run by users o Not typically considered part of OS o Launched by command line, mouse click, finger poke