Ch 2 Flashcards
types of user interfaces
Command line interface - or command interpreter (a shell) Batch - commands are entered into files and those files are executed Grafical (GUI) -
system calls
interface to services generally write in C, C++, or assembly (a system of tasks)
API
the “menu” in the restaurant analogy Specifies a set of functions that are available to programers. An API invokes a System Call i.e. read(), fork(), open(), etc.
System Call Interface
link between System Calls and API (a set of functions built into libraries included with a compiler)
System Program or Program Utility pg 77
provides a convenient environment for program development and execution i.e. background services, language support, file modification
Operating-System Structure
Simple - written to provide the most functionality in the least space. Vulnerable to errant users. Layered - easy to debug. Not efficient, bottom layer only accessed by top. Microkernel - Unessential task taken away from kernel. optimizes comm. b/w client and services (message passing) . Mods are easy. Not efficient; system func overhead Module (best) - loadable kernel
policy vs mechanism
policies - what to do mechanisms - how to do it
important for flxibility, in best case scenario, when mechanisims are incensitive to policies, a change in policy only requires the redefinitont of a few parmeters.
monolithic kernel
when the entire OS is working in kernel space
crash (“blue screen,” not application crash)
failure in kernel
Typical microkernel architecture
Typical layered operating system
typical module os
Typical simple OS
Passing parameters to OS
may be done by passing in registers, address of parameter stored in a block, pushed into a stack and popped of by the OS
process control (system call examples)
end, abort, load, execute, create/terminate process, wait, allocate/free memory
