vault backup: 2022-09-21 12:24:30

content/notes/13-OS-intro.md

@@ -4,9 +4,11 @@ aliases:
 tags: 
 - cosc204
 - lecture
+sr-due: 2022-09-24
+sr-interval: 3
+sr-ease: 250
 ---
 
-
 # why learn OS
 - security
 - optimisation
@@ -19,4 +21,78 @@ tags:
 # what is an OS
 ![big picture diagram|400](https://i.imgur.com/9O1YR0p.png)
 -  a program (also called OS kernel) loaded onto RAM first when pc is turned on
-- OS kernel (in kernel space)
+- OS kernel (in kernel space) has highest privilege and can access any hardware directly
+- user programs (in user space) cannot acces hardware unless permitted otherwise by the OS kernel via service request (sys call)
+
+> a program (OS kernel) that manages the different aspects of the opereration of the machine and runs with the highest privilege in a protected domain
+
+manages:
+	- processes
+	- data storage
+		- ram, file systems
+	- io devices
+		- network
+		- ui
+	- security and protection
+
+## kernel vs user space
+- cpu can check space of software via  flag in status word
+- when interrupt or sys call occurs, the flag is ser to kernel space
+- kernel
+	- protected space where software can access hardware
+	- OS kernel is run in kernel space
+- user
+	- other software is run in user space
+	- non privilege space where softwar cannot access hardware
+	- unless permitted by kernel
+
+## process management
+a process is a program in execution
+- a program is not a process
+
+process management involves
+- creating and deleting processes 
+- scheduling processes 
+- suspending and resuming processes 
+- process synchronisation 
+- process communication 
+- deadlock handling
+
+## storage manangement
+storage: 
+- primary (RAM)
+- secondary (hard drive)
+- tertiary (floppy disks, tapes, cd, etc)
+
+storage manangement involves:
+- Allocating and deallocating storage 
+- Keeping track of storage in use and free storage 
+- Transferring data between primary and secondary storage
+
+Defn: the file system is the mechanism by which the user accesses/manipulates sotred data in secndary storage like hard disk
+
+## io device managment
+- A computer system can include a very wide range of I/O devices: keyboards, mice, printers, hard disks, CD-roms, etc etc etc. 
+
+I/O device management includes tasks like: 
+- tracking the status of each device 
+- allocating devices to particular processes 
+- deallocating devices 
+- scheduling tasks for individual devices (e.g. disk scheduling) 
+- these functions are built into modules called device drivers; each device needs one device driver to manage the hardware and serve the requests from user applications via the OS kernel.
+
+### UI
+Defn: the shell is the program through which the user interactins with the operating system
+
+two types:
+- icon based point and click
+- keyboard commands e.g., UNIX
+	- harder to learn but more powerful and flexible
+
+# history
+- No OS
+- batch systems
+- spooling
+- time sharing
+- real time
+- 

content/notes/cosc-204.md

@@ -41,7 +41,7 @@ tags:
 - [08-intro-to-c](notes/08-intro-to-c.md)
 - [11-struct-and-union](notes/11-struct-and-union.md)
 - [12-pointers-to-routines](notes/12-pointers-to-routines.md)
-- 
+- [13-OS-intro](notes/13-OS-intro.md)
 
 # Archive