note update

os

content/DSA/Data Structure/Array/Array.md

@@ -6,7 +6,7 @@ Author Profile:
 tags:
   - dsa
 Creation Date: 2023-10-08T20:10:00
-Last Date: 2023-12-12T10:24:35+08:00
+Last Date: 2023-12-20T16:19:21+08:00
 References: 
 ---
 ## Abstract
@@ -34,8 +34,8 @@ References:
 >- However, it is Θ(1), Theta(1) to insert/delete
 
 >[!info] Performance comparison with [[Linked List]] when going through all elements
->- Array is much faster if there is [[Cache]], otherwise it will be slightly slower (Because Array has to calculate the address of the next element, while [[Linked List]] is already calculated)
->- Array faster with [[Cache]] is because it is stored in a [[Data Structure#Continuous Memory]] manner, and can take advantage of [[Cache Locality (Locality of Reference)]]
+>- Array is much faster if there is [[CPU Cache]], otherwise it will be slightly slower (Because Array has to calculate the address of the next element, while [[Linked List]] is already calculated)
+>- Array faster with CPU Cache is because it is stored in a [[Data Structure#Continuous Memory]] manner, and can take advantage of [[CPU Cache#Cache Locality]]
 
 
 ## Properties

content/DSA/Data Structure/Stack/Stack (FILO).md

@@ -6,15 +6,14 @@ Author Profile:
 tags:
   - dsa
 Creation Date: 2023-10-07T16:38:28+08:00
-Last Date: 2023-10-07T16:38:28+08:00
-References:
+Last Date: 2023-12-20T16:24:30+08:00
+References: 
 ---
-## Basics
+## Abstract
 ---
->[!abstract] Basic Properties
->![[stack.png]]
->- [[Linear Data Structure]]
->- Aka [[Array]]/[[Linked List]] with limitations
+![[stack.png]]
+- [[Linear Data Structure]]
+- Aka [[Array]]/[[Linked List]] with limitations
 
 
 >[!caution] Stack is more about the having the push(), pop() & peek() in O(1) on a particular data structure 
@@ -47,9 +46,9 @@ References:
 >- Both support without much difference
 
 >[!note] Time Efficiency
->- [[Array]] has [[Cache Locality]] to take advantage of [[Cache]] for extreme fast access. But [[Array]] has fixed size, if there isn't any space, that particular insertion operation will be O(n)
+>- [[Array]] has [[Cache Locality]] to take advantage of [[CPU Cache]] for extreme fast access. But Array has fixed size, if there isn't any space, that particular insertion operation will be O(n)
 >- [[Linked List]] has to use extra time to perform pointer operation 
->- Conclusion: [[Array]] has slightly better time efficiency, since expansion is a low frequency operation, while pointer operation occurs whenever there is an insertion operation. However, [[Linked List]] has more stable performance
+>- Conclusion: Array has slightly better time efficiency, since expansion is a low frequency operation, while pointer operation occurs whenever there is an insertion operation. However, [[Linked List]] has more stable performance
 
 >[!note] Space Efficiency
 >- [[Array]] get a pre-defined [[Main Memory]] size, and each expansion is usually double the original size which may exceed the actual demand
@@ -63,14 +62,3 @@ References:
 >[!success] O(1) to pop()
 
 >[!success] O(1) to peek()
-
-
-## Side Notes
----
->[!success]
-
->[!success] 
-
->[!success] 
-
->[!success] 

content/Networking/Application Layer/DNS/Features/DNS Caching.md

@@ -6,9 +6,10 @@ Author Profile:
 tags:
   - networking
 Creation Date: 2023-07-23T18:40:57+08:00
-Last Date: 2023-07-23T18:40:57+08:00
-References:
+Last Date: 2023-12-20T16:23:17+08:00
+References: 
 ---
->[!note]
->- [[Cache]] [[DNS]] mappings in the [[Main Memory]]
->- This allows us to bypass some or all the servers in [[DNS Servers]]
+## Abstract
+---
+- Cache [[DNS]] mappings in the [[Main Memory]]
+- This allows us to bypass some or all the servers in [[DNS Servers]]

content/OS/MISC/Booting/BIOS.md

@@ -6,9 +6,17 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-07-15T16:58:57+08:00
-Last Date: 2023-07-15T16:58:57+08:00
-References:
+Last Date: 2023-12-20T15:28:16+08:00
+References: 
 ---
-> [!note]
-> - Contains low-level IO software
-> - Nowadays, stored in [[Flash RAM]] - nonvolatile & can be updated
+## Abstract
+---
+- Contains low-level IO software
+- Nowadays, stored in **Flash RAM** - nonvolatile & can be updated
+
+## BIOS in Booting
+---
+1. Checks [[Main Memory]] capacity
+2. Check [[IO Device]]
+3. Scanning [[IO Bus#PCI Bus]] etc to detect all devices attached
+4. Determine the **Boot Device** by trying out a list of devices stored in the **CMOS**

content/OS/MISC/Booting/Boot Device.md

@@ -0,0 +1,30 @@
+---
+Author:
+  - Xinyang YU
+Author Profile:
+  - https://linkedin.com/in/xinyang-yu
+tags:
+  - OS
+Creation Date: 2023-12-20, 15:30
+Last Date: 2023-12-20T15:33:38+08:00
+References: 
+---
+## Abstract
+---
+- Physical or logical storage device that contains [[#Master Boot Record]]
+
+## Boot Device in Booting
+---
+1. [[#Master Boot Record]] is read into [[Main Memory]]
+2. [[#Secondary Boot Loader]] started
+
+## Terminologies
+---
+### Master Boot Record
+- Contains [[#Primary Boot Loader]]
+### Primary Boot Loader
+- Initiate the process of loading the [[OS]] into the computer's [[Main Memory]]
+- Examines the **partition table** at the end of **boot sector** to determine which **partition** is active. Providing a menu for user to select which OS to boot
+
+### Secondary Boot Loader
+- Loading the [[Kernel]] and initialising the [[OS]] environment from **active partition** and start it

content/OS/MISC/Booting/Booting Computer.md

@@ -6,21 +6,12 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-07-15T17:02:04+08:00
-Last Date: 2023-12-14T19:32:16+08:00
+Last Date: 2023-12-20T15:37:43+08:00
 References: 
 ---
->[!note]
->Booting sequence
->1. [[BIOS]] started
->	1. Checks [[Main Memory]] capacity
->	2. Check [[IO Device]]
->		1. Scanning [[Peripheral Component Interconnect Express (PCIe) bus]] etc to detect all devices attached
->	3. Determine the [[Boot Device]] by trying out a list of devies stored in the [[CMOS]]
->2. Boot Device started
->	1. [[First sector from the boot device]] is read into memory & executed
->3. [[Secondary Boot loader]] started
->4. [[OS]] started
->	1. Get configuration info from BIOS
->	2. Check missing [[Device Controller#Device Driver]]
->	3. [[Initialize table]]
->	4. Starts up a login program/GUI
+## Abstract
+---
+A 3-steps process
+1. [[BIOS#BIOS in Booting]]
+2. [[Boot Device#Boot Device in Booting]]
+3. [[OS#OS in Booting]]

content/OS/Main Components/IO/Hardware/IO Device.md → content/OS/Main Components/IO/Device Controller.md

@@ -5,19 +5,18 @@ Author Profile:
   - https://linkedin.com/in/xinyang-yu
 tags:
   - OS
-Creation Date: 2023-07-14T20:53:45+08:00
-Last Date: 2023-12-18T17:25:17+08:00
+Creation Date: 2023-10-29T20:13:44
+Last Date: 2023-12-20T15:46:50+08:00
 References: 
 ---
 ## Abstract
----
-* Controlled by [[Device Controller]]
-* Examples are like keyboard and monitor 
-
-
+* A small embedded computers that are programmed to tell [[IO Device]] what to do
+* Communicates with [[OS]] over [[#Device Driver]]
 
 ## Terminologies
 ---
+### Device Driver
+- A piece of software that allows [[OS]] to talk to the [[Device Controller]] over a standardised interface
 ### IO Device Register
 - Used to control [[IO Device]]
 - Act as *interfaces* between the [[CPU]] and external devices such as hard drives, keyboards, printers, and more

content/OS/Main Components/IO/Hardware/Direct Memory Access (DMA).md → content/OS/Main Components/IO/Direct Memory Access (DMA).md

@@ -6,7 +6,16 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-08-27T14:44:16+08:00
-Last Date: 2023-12-18T17:26:53+08:00
+Last Date: 2023-12-20T15:43:57+08:00
 References: 
 ---
-* Chip that control the flow of bits between [[Main Memory]] and some [[Device Controller]] without constant [[CPU]] intervention
+## Abstract
+---
+* Chip that control the flow of bits between [[Main Memory]] and some [[Device Controller]] without constant [[CPU]] intervention, solves [[#Busy Waiting]]
+
+
+
+## Terminologies
+---
+### Busy Waiting
+* Has a big disadvantage of involving [[CPU]] keep polling until [[Device Controller]] retrieves data from [[IO Device]]

content/OS/Main Components/IO/IO Bus.md

@@ -6,12 +6,14 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-07-14T21:06:58+08:00
-Last Date: 2023-12-18T17:31:36+08:00
+Last Date: 2023-12-20T15:48:07+08:00
 References: 
 ---
 ## Abstract
 ---
 - A *communication pathway* within a computer system that facilitates the exchange of *data* between the [[CPU]], [[Main Memory]], and [[IO Device]]
+- [[#Common Bus]]
+
 
 ## IO Bus Architecture
 ---
@@ -20,4 +22,13 @@ References:
 ### Parallel Bus Architecture
 * Send each [[Computer Data Representation#Word]] of data over multiple wires
 ### Serial Bus Architecture
-- Send all [[Computer Data Representation#Bit]] in a single connection/lane
+- Send all [[Computer Data Representation#Bit]] in a single connection/lane
+
+
+## Common Bus
+---
+### PCI Bus
+- Uses [[#Serial Bus Architecture]]
+### USA
+
+### SATA

content/OS/Main Components/IO/IO Device.md

@@ -0,0 +1,25 @@
+---
+Author:
+  - Xinyang YU
+Author Profile:
+  - https://linkedin.com/in/xinyang-yu
+tags:
+  - OS
+Creation Date: 2023-07-14T20:53:45+08:00
+Last Date: 2023-12-20T15:44:46+08:00
+References: 
+---
+## Abstract
+---
+* Controlled by [[Device Controller]]
+* Examples are like keyboard and monitor 
+
+
+
+ ## Terminologies
+---
+### Plug and Play
+- [[OS]] automatically collect information about the [[IO Device]]
+- Centrally assign **interrupt level** & **IO Addresses**
+- Tell each IO device what its numbers are
+- Works closely with [[Booting Computer]]