vault backup: 2022-09-21 13:39:30

content/notes/14-processes-and-system-calls.md

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+---
+title: "14-processes-and-system-calls"
+aliases: 
+tags: 
+- cosc204
+- lecture
+---
+
+- heirarchical structure in software systems
+- system calls and interrupts
+- representing process in OSs
+- overview of process scheduling
+
+# Heirarchical structure
+software systems have modularity
+- os kernel
+- system programs
+- applicatioin programs
+![Heirarchical structure diagram|400](https://i.imgur.com/Tf7QDTy.png)
+
+## application programs
+Defn: a program that ordinary usrers interact with, running in user space
+
+e.g.,
+- word processor
+- video player
+- web browser
+- games
+- etc
+
+## system programs/libraries
+Defn: a program which provides general purpose power level function, packeages in a way which is convenient for a user (e.g., sys admin or programmer) to employ
+
+system program types include.,
+- file manipulation progarms
+- status info programs
+- network and device management programs
+- compilers assemblers and interpreters
+- various library code
+- command shell programs (e.g., command interpreters)
+
+also runs in user space
+
+## system calls
+