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crazylion lee

Xplain - 0 views

magcius.github.io/...article

Xorg x11 linux

shared by crazylion lee on 10 Jul 16 - No Cached
  • crazylion lee on 10 Jul 16
     
    "Last year, I wrote an article describing the free and open-source graphics stack, explaining all of the interconnected pieces: X11, graphics drivers, DRM, and DRI, and their roles in getting pixels placed on the screen. In the year since, I've answered a lot of really good questions from the Linux community about my post, about X11, and about Wayland. I've learned a lot. Several new technologies have appeared, and I have started to take a more active role in this myself, as part of our efforts to port GNOME to Wayland."
crazylion lee

Security Onion - 0 views

security-onion-solutions.github.io/security-onion

security onion linux distribution

shared by crazylion lee on 18 Nov 15 - No Cached
  • crazylion lee on 18 Nov 15
     
    "Security Onion is a Linux distro for intrusion detection, network security monitoring, and log management. It's based on Ubuntu and contains Snort, Suricata, Bro, OSSEC, Sguil, Squert, ELSA, Xplico, NetworkMiner, and many other security tools. The easy-to-use Setup wizard allows you to build an army of distributed sensors for your enterprise in minutes!"
張 旭

How To Use Bash's Job Control to Manage Foreground and Background Processes | DigitalOcean - 0 views

www.digitalocean.com/...round-and-background-processes

linux system server command

shared by 張 旭 on 06 Feb 18 - No Cached
  • Most processes that you start on a Linux machine will run in the foreground. The command will begin execution, blocking use of the shell for the duration of the process.
  • By default, processes are started in the foreground. Until the program exits or changes state, you will not be able to interact with the shell.
  • stop the process by sending it a signal
  • ...17 more annotations...
  • Linux terminals are usually configured to send the "SIGINT" signal (typically signal number 2) to current foreground process when the CTRL-C key combination is pressed.
  • Another signal that we can send is the "SIGTSTP" signal (typically signal number 20).
  • A background process is associated with the specific terminal that started it, but does not block access to the shell
  • start a background process by appending an ampersand character ("&") to the end of your commands.
  • type commands at the same time.
  • The [1] represents the command's "job spec" or job number. We can reference this with other job and process control commands, like kill, fg, and bg by preceding the job number with a percentage sign. In this case, we'd reference this job as %1.
  • Once the process is stopped, we can use the bg command to start it again in the background
  • By default, the bg command operates on the most recently stopped process.
  • Whether a process is in the background or in the foreground, it is rather tightly tied with the terminal instance that started it
  • When a terminal closes, it typically sends a SIGHUP signal to all of the processes (foreground, background, or stopped) that are tied to the terminal.
  • a terminal multiplexer
  • start it using the nohup command
  • appending output to ‘nohup.out’
  • pgrep -a
  • The disown command, in its default configuration, removes a job from the jobs queue of a terminal.
  • You can pass the -h flag to the disown process instead in order to mark the process to ignore SIGHUP signals, but to otherwise continue on as a regular job
  • The huponexit shell option controls whether bash will send its child processes the SIGHUP signal when it exits.
crazylion lee

GitHub - rancher/os: Tiny Linux distro that runs the entire OS as Docker containers - 0 views

github.com/os

docker os container

shared by crazylion lee on 14 May 17 - No Cached
  • crazylion lee on 14 May 17
     
    "Tiny Linux distro that runs the entire OS as Docker containers "
張 旭

鳥哥的 Linux 私房菜 -- 第二章、主機規劃與磁碟分割 - 0 views

linux.vbird.org/...0130designlinux.php

linux system

shared by 張 旭 on 23 Jun 21 - Cached
  • BIOS會依據使用者的設定去取得能夠開機的硬碟， 並且到該硬碟裡面去讀取第一個磁區的MBR位置。 MBR這個僅有446 bytes的硬碟容量裡面會放置最基本的開機管理程式， 此時BIOS就功成圓滿，而接下來就是MBR內的開機管理程式的工作了。
  • 開機管理程式的目的是在載入(load)核心檔案， 由於開機管理程式是作業系統在安裝的時候所提供的，所以他會認識硬碟內的檔案系統格式，因此就能夠讀取核心檔案， 然後接下來就是核心檔案的工作，開機管理程式與 BIOS 也功成圓滿
  • 開機管理程式除了可以安裝在MBR之外， 還可以安裝在每個分割槽的開機磁區(boot sector)
  • 張 旭 on 23 Jun 21
     
    "BIOS會依據使用者的設定去取得能夠開機的硬碟， 並且到該硬碟裡面去讀取第一個磁區的MBR位置。 MBR這個僅有446 bytes的硬碟容量裡面會放置最基本的開機管理程式， 此時BIOS就功成圓滿，而接下來就是MBR內的開機管理程式的工作了。"
張 旭

Memory inside Linux containers | Fabio Kung - 0 views

fabiokung.com/...memory-inside-linux-containers

linux docker system process

shared by 張 旭 on 05 Dec 19 - No Cached
  • /sys/fs/cgroup/ is the recommended location for cgroup hierarchies, but it is not a standard.
  • most container specific metrics are available at the cgroup filesystem via /path/to/cgroup/memory.stat, /path/to/cgroup/memory.usage_in_bytes, /path/to/cgroup/memory.limit_in_bytes and others.
  • cat /sys/fs/cgroup/memory/memory.stat
  • ...3 more annotations...
  • /sys/fs/cgroup is just an umbrella for all cgroup hierarchies, there is no recommendation or standard for my own cgroup location.
  • an userspace library that processes can use to query their memory usage and available memory.
  • we might need to encourage people to stop using those tools inside containers.
張 旭

Container Runtimes | Kubernetes - 0 views

kubernetes.io/...container-runtimes

kubernetes container docker devops

shared by 張 旭 on 25 Jan 23 - No Cached
  • Kubernetes releases before v1.24 included a direct integration with Docker Engine, using a component named dockershim. That special direct integration is no longer part of Kubernetes
  • You need to install a container runtime into each node in the cluster so that Pods can run there.
  • Kubernetes 1.26 requires that you use a runtime that conforms with the Container Runtime Interface (CRI).
  • ...9 more annotations...
  • On Linux, control groups are used to constrain resources that are allocated to processes.
  • Both kubelet and the underlying container runtime need to interface with control groups to enforce resource management for pods and containers and set resources such as cpu/memory requests and limits.
  • When the cgroupfs driver is used, the kubelet and the container runtime directly interface with the cgroup filesystem to configure cgroups.
  • The cgroupfs driver is not recommended when systemd is the init system
  • When systemd is chosen as the init system for a Linux distribution, the init process generates and consumes a root control group (cgroup) and acts as a cgroup manager.
  • Two cgroup managers result in two views of the available and in-use resources in the system.
  • Changing the cgroup driver of a Node that has joined a cluster is a sensitive operation. If the kubelet has created Pods using the semantics of one cgroup driver, changing the container runtime to another cgroup driver can cause errors when trying to re-create the Pod sandbox for such existing Pods. Restarting the kubelet may not solve such errors.
  • The approach to mitigate this instability is to use systemd as the cgroup driver for the kubelet and the container runtime when systemd is the selected init system.
  • Kubernetes 1.26 defaults to using v1 of the CRI API. If a container runtime does not support the v1 API, the kubelet falls back to using the (deprecated) v1alpha2 API instead.
crazylion lee

BearSSL - 0 views

bearssl.org

openssl ssl tls

shared by crazylion lee on 11 Nov 16 - No Cached
  • crazylion lee on 11 Nov 16
     
    "BearSSL is an implementation of the SSL/TLS protocol (RFC 5246) written in C. It aims at offering the following features: Be correct and secure. In particular, insecure protocol versions and choices of algorithms are not supported, by design; cryptographic algorithm implementations are constant-time by default. Be small, both in RAM and code footprint. For instance, a minimal server implementation may fit in about 20 kilobytes of compiled code and 25 kilobytes of RAM. Be highly portable. BearSSL targets not only "big" operating systems like Linux and Windows, but also small embedded systems and even special contexts like bootstrap code. Be feature-rich and extensible. SSL/TLS has many defined cipher suites and extensions; BearSSL should implement most of them, and allow extra algorithm implementations to be added afterwards, possibly from third parties."
crazylion lee

strongSwan - IPsec VPN for Linux, Android, FreeBSD, Mac OS X, Windows - 0 views

www.strongswan.org

vpn linux OpenSource ipsec

shared by crazylion lee on 01 Jan 17 - No Cached
  • Current Release: 5.5.1 Download - Changelog strongSwan   the OpenSource IPsec-based VPN Solution
crazylion lee

Nix: The Purely Functional Package Manager - 0 views

nixos.org/nix

nix homebrew package management

shared by crazylion lee on 28 May 16 - No Cached
  • crazylion lee on 28 May 16
     
    "Nix The Purely Functional Package Manager Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. It provides atomic upgrades and rollbacks, side-by-side installation of multiple versions of a package, multi-user package management and easy setup of build environments. Read more…"
crazylion lee

NATRON - 0 views

natron.fr

compositing opensource compose

shared by crazylion lee on 27 Jun 16 - No Cached
  • crazylion lee on 27 Jun 16
     
    "Free and open-source compositing software, available for MacOS X, Windows and Linux."
crazylion lee

BFH ImagePlay - Rapid Prototyping for Image Processing - 0 views

imageplay.io

processing image

shared by crazylion lee on 06 Aug 15 - No Cached
  • crazylion lee on 06 Aug 15
     
    "ImagePlay is a rapid prototyping tool for building and testing image processing algorithms. It comes with a variety of over 70 individual image processors which can be combined into complex process chains. ImagePlay is completely open source and can be built for Windows, Mac and Linux."
張 旭

How To Install and Use Docker: Getting Started | DigitalOcean - 0 views

www.digitalocean.com/...and-use-docker-getting-started

docker system deploy

shared by 張 旭 on 26 Oct 14 - No Cached
  • docker as a project offers you the complete set of higher-level tools to carry everything that forms an application across systems and machines - virtual or physical - and brings along loads more of great benefits with it
  • docker daemon: used to manage docker (LXC) containers on the host it runs
  • docker CLI: used to command and communicate with the docker daemon
  • ...20 more annotations...
  • containers: directories containing everything-your-application
  • images: snapshots of containers or base OS (e.g. Ubuntu) images
  • Dockerfiles: scripts automating the building process of images
  • Docker containers are basically directories which can be packed (e.g. tar-archived) like any other, then shared and run across various different machines and platforms (hosts).
  • Linux Containers can be defined as a combination various kernel-level features (i.e. things that Linux-kernel can do) which allow management of applications (and resources they use) contained within their own environment
  • Each container is layered like an onion and each action taken within a container consists of putting another block (which actually translates to a simple change within the file system) on top of the previous one.
  • Each docker container starts from a docker image which forms the base for other applications and layers to come.
  • Docker images constitute the base of docker containers from which everything starts to form
  • a solid, consistent and dependable base with everything that is needed to run the applications
  • As more layers (tools, applications etc.) are added on top of the base, new images can be formed by committing these changes.
  • a Dockerfile for automated image building
  • Dockerfiles are scripts containing a successive series of instructions, directions, and commands which are to be executed to form a new docker image.
  • As you work with a container and continue to perform actions on it (e.g. download and install software, configure files etc.), to have it keep its state, you need to “commit”.
  • Please remember to “commit” all your changes.
  • When you "run" any process using an image, in return, you will have a container.
  • When the process is not actively running, this container will be a non-running container. Nonetheless, all of them will reside on your system until you remove them via rm command.
  • To create a new container, you need to use a base image and specify a command to run.
  • you can not change the command you run after having created a container (hence specifying one during "creation")
  • If you would like to save the progress and changes you made with a container, you can use “commit”
  • turns your container to an image
crazylion lee

Nmap: the Network Mapper - Free Security Scanner - 1 views

nmap.org

security network

shared by crazylion lee on 22 Nov 15 - No Cached
  • crazylion lee on 22 Nov 15
     
    "Nmap ("Network Mapper") is a free and open source (license) utility for network discovery and security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. It was designed to rapidly scan large networks, but works fine against single hosts. Nmap runs on all major computer operating systems, and official binary packages are available for Linux, Windows, and Mac OS X. In addition to the classic command-line Nmap executable, the Nmap suite includes an advanced GUI and results viewer (Zenmap), a flexible data transfer, redirection, and debugging tool (Ncat), a utility for comparing scan results (Ndiff), and a packet generation and response analysis tool (Nping)."
張 旭

bbatsov/rails-style-guide: A community-driven Ruby on Rails 4 style guide - 0 views

github.com/...rails-style-guide

rails programming code style

shared by 張 旭 on 07 May 17 - No Cached
  • custom initialization code in config/initializers. The code in initializers executes on application startup
  • Keep initialization code for each gem in a separate file with the same name as the gem
  • Mark additional assets for precompilation
  • ...90 more annotations...
  • config/environments/production.rb
  • Create an additional staging environment that closely resembles the production one
  • Keep any additional configuration in YAML files under the config/ directory
  • Rails::Application.config_for(:yaml_file)
  • Use nested routes to express better the relationship between ActiveRecord models
  • nest routes more than 1 level deep then use the shallow: true option
  • namespaced routes to group related actions
  • Don't use match to define any routes unless there is need to map multiple request types among [:get, :post, :patch, :put, :delete] to a single action using :via option.
  • Keep the controllers skinny
  • all the business logic should naturally reside in the model
  • Share no more than two instance variables between a controller and a view.
  • using a template
  • Prefer render plain: over render text
  • Prefer corresponding symbols to numeric HTTP status codes
  • without abbreviations
  • Keep your models for business logic and data-persistence only
  • Avoid altering ActiveRecord defaults (table names, primary key, etc)
  • Group macro-style methods (has_many, validates, etc) in the beginning of the class definition
  • Prefer has_many :through to has_and_belongs_to_many
  • self[:attribute]
  • self[:attribute] = value
  • validates
  • Keep custom validators under app/validators
  • Consider extracting custom validators to a shared gem
  • preferable to make a class method instead which serves the same purpose of the named scope
  • returns an ActiveRecord::Relation object
  • .update_attributes
  • Override the to_param method of the model
  • Use the friendly_id gem. It allows creation of human-readable URLs by using some descriptive attribute of the model instead of its id
  • find_each to iterate over a collection of AR objects
  • .find_each
  • .find_each
  • Looping through a collection of records from the database (using the all method, for example) is very inefficient since it will try to instantiate all the objects at once
  • always call before_destroy callbacks that perform validation with prepend: true
  • Define the dependent option to the has_many and has_one associations
  • always use the exception raising bang! method or handle the method return value.
  • When persisting AR objects
  • Avoid string interpolation in queries
  • param will be properly escaped
  • Consider using named placeholders instead of positional placeholders
  • use of find over where when you need to retrieve a single record by id
  • use of find_by over where and find_by_attribute
  • use of where.not over SQL
  • use heredocs with squish
  • Keep the schema.rb (or structure.sql) under version control.
  • Use rake db:schema:load instead of rake db:migrate to initialize an empty database
  • Enforce default values in the migrations themselves instead of in the application layer
  • change_column_default
  • imposing data integrity from the Rails app is impossible
  • use the change method instead of up and down methods.
  • constructive migrations
  • use models in migrations, make sure you define them so that you don't end up with broken migrations in the future
  • Don't use non-reversible migration commands in the change method.
  • In this case, block will be used by create_table in rollback
  • Never call the model layer directly from a view
  • Never make complex formatting in the views, export the formatting to a method in the view helper or the model.
  • When the labels of an ActiveRecord model need to be translated, use the activerecord scope
  • Separate the texts used in the views from translations of ActiveRecord attributes
  • Place the locale files for the models in a folder locales/models
  • the texts used in the views in folder locales/views
  • config/application.rb config.i18n.load_path += Dir[Rails.root.join('config', 'locales', '**', '*.{rb,yml}')]
  • I18n.t
  • I18n.l
  • Use "lazy" lookup for the texts used in views.
  • Use the dot-separated keys in the controllers and models
  • Reserve app/assets for custom stylesheets, javascripts, or images
  • Third party code such as jQuery or bootstrap should be placed in vendor/assets
  • Provide both HTML and plain-text view templates
  • config.action_mailer.raise_delivery_errors = true
  • Use a local SMTP server like Mailcatcher in the development environment
  • Provide default settings for the host name
  • The _url methods include the host name and the _path methods don't
  • _url
  • Format the from and to addresses properly
  • default from:
  • sending html emails all styles should be inline
  • Sending emails while generating page response should be avoided. It causes delays in loading of the page and request can timeout if multiple email are sent.
  • .start_with?
  • .end_with?
  • &.
  • Config your timezone accordingly in application.rb
  • config.active_record.default_timezone = :local
  • it can be only :utc or :local
  • Don't use Time.parse
  • Time.zone.parse
  • Don't use Time.now
  • Time.zone.now
  • Put gems used only for development or testing in the appropriate group in the Gemfile
  • Add all OS X specific gems to a darwin group in the Gemfile, and all Linux specific gems to a linux group
  • Do not remove the Gemfile.lock from version control.
張 旭

鳥哥的 Linux 私房菜 -- 第零章、計算機概論 - 0 views

linux.vbird.org/...0105computers.php

system

shared by 張 旭 on 22 Jun 21 - No Cached
  • 但因為 CPU 的運算速度比其他的設備都要來的快，又為了要滿足 FSB 的頻率，因此廠商就在 CPU 內部再進行加速， 於是就有所謂的外頻與倍頻了。
  • 中央處理器 (Central Processing Unit, CPU)，CPU 為一個具有特定功能的晶片， 裡頭含有微指令集，如果你想要讓主機進行什麼特異的功能，就得要參考這顆 CPU 是否有相關內建的微指令集才可以。
  • CPU 內又可分為兩個主要的單元，分別是： 算數邏輯單元與控制單元。
  • ...63 more annotations...
  • CPU 讀取的資料都是從主記憶體來的！ 主記憶體內的資料則是從輸入單元所傳輸進來！而 CPU 處理完畢的資料也必須要先寫回主記憶體中，最後資料才從主記憶體傳輸到輸出單元。
  • 重點在於 CPU 與主記憶體。 特別要看的是實線部分的傳輸方向，基本上資料都是流經過主記憶體再轉出去的！
  • CPU 實際要處理的資料則完全來自於主記憶體 (不管是程式還是一般文件資料)！這是個很重要的概念喔！ 這也是為什麼當你的記憶體不足時，系統的效能就很糟糕！
  • 常見到的兩種主要 CPU 架構， 分別是：精簡指令集 (RISC) 與複雜指令集 (CISC) 系統。
  • 微指令集較為精簡，每個指令的執行時間都很短，完成的動作也很單純，指令的執行效能較佳； 但是若要做複雜的事情，就要由多個指令來完成。
  • CISC在微指令集的每個小指令可以執行一些較低階的硬體操作，指令數目多而且複雜， 每條指令的長度並不相同。因為指令執行較為複雜所以每條指令花費的時間較長， 但每條個別指令可以處理的工作較為豐富。
  • 多媒體微指令集：MMX, SSE, SSE2, SSE3, SSE4, AMD-3DNow! 虛擬化微指令集：Intel-VT, AMD-SVM 省電功能：Intel-SpeedStep, AMD-PowerNow! 64/32位元相容技術：AMD-AMD64, Intel-EM64T
  • 若光以效能來說，目前的個人電腦效能已經夠快了，甚至已經比工作站等級以上的電腦運算速度還要快！ 但是工作站電腦強調的是穩定不當機，並且運算過程要完全正確，因此工作站以上等級的電腦在設計時的考量與個人電腦並不相同啦
  • 1 Byte = 8 bits
  • 檔案容量使用的是二進位的方式，所以 1 GBytes 的檔案大小實際上為：1024x1024x1024 Bytes 這麼大！ 速度單位則常使用十進位，例如 1GHz 就是 1000x1000x1000 Hz 的意思。
  • CPU的運算速度常使用 MHz 或者是 GHz 之類的單位，這個 Hz 其實就是秒分之一
  • 在網路傳輸方面，由於網路使用的是 bit 為單位，因此網路常使用的單位為 Mbps 是 Mbits per second，亦即是每秒多少 Mbit
  • (1)北橋：負責連結速度較快的CPU、主記憶體與顯示卡界面等元件
  • (2)南橋：負責連接速度較慢的裝置介面， 包括硬碟、USB、網路卡等等
  • CPU內部含有微指令集，不同的微指令集會導致CPU工作效率的優劣
  • 時脈就是CPU每秒鐘可以進行的工作次數。 所以時脈越高表示這顆CPU單位時間內可以作更多的事情。
  • 早期的 CPU 架構主要透過北橋來連結系統最重要的 CPU、主記憶體與顯示卡裝置。因為所有的設備都得掉透過北橋來連結，因此每個設備的工作頻率應該要相同。
  • 前端匯流排 (FSB)
  • 外頻指的是CPU與外部元件進行資料傳輸時的速度
  • 倍頻則是 CPU 內部用來加速工作效能的一個倍數
  • 新的 CPU 設計中， 已經將記憶體控制器整合到 CPU 內部，而連結 CPU 與記憶體、顯示卡的控制器的設計，在Intel部份使用 QPI (Quick Path Interconnect) 與 DMI 技術，而 AMD 部份則使用 Hyper Transport 了，這些技術都可以讓 CPU 直接與主記憶體、顯示卡等設備分別進行溝通，而不需要透過外部的連結晶片了。
  • 如何知道主記憶體能提供的資料量呢？此時還是得要藉由 CPU 內的記憶體控制晶片與主記憶體間的傳輸速度『前端匯流排速度(Front Side Bus, FSB)
  • 主記憶體也是有其工作的時脈，這個時脈限制還是來自於 CPU 內的記憶體控制器所決定的。
  • CPU每次能夠處理的資料量稱為字組大小(word size)， 字組大小依據CPU的設計而有32位元與64位元。我們現在所稱的電腦是32或64位元主要是依據這個 CPU解析的字組大小而來的
  • 早期的32位元CPU中，因為CPU每次能夠解析的資料量有限， 因此由主記憶體傳來的資料量就有所限制了。這也導致32位元的CPU最多只能支援最大到4GBytes的記憶體。
  • 在每一個 CPU 內部將重要的暫存器 (register) 分成兩群， 而讓程序分別使用這兩群暫存器。
  • 可以有兩個程序『同時競爭 CPU 的運算單元』，而非透過作業系統的多工切換！
  • 大多發現 HT 雖然可以提昇效能，不過，有些情況下卻可能導致效能降低喔！因為，實際上明明就僅有一個運算單元
  • 個人電腦的主記憶體主要元件為動態隨機存取記憶體(Dynamic Random Access Memory, DRAM)， 隨機存取記憶體只有在通電時才能記錄與使用，斷電後資料就消失了。因此我們也稱這種RAM為揮發性記憶體。
  • 要啟用雙通道的功能你必須要安插兩支(或四支)主記憶體，這兩支記憶體最好連型號都一模一樣比較好， 這是因為啟動雙通道記憶體功能時，資料是同步寫入/讀出這一對主記憶體中，如此才能夠提升整體的頻寬啊！
  • 第二層快取(L2 cache)整合到CPU內部，因此這個L2記憶體的速度必須要CPU時脈相同。 使用DRAM是無法達到這個時脈速度的，此時就需要靜態隨機存取記憶體(Static Random Access Memory, SRAM)的幫忙了。
  • BIOS(Basic Input Output System)是一套程式，這套程式是寫死到主機板上面的一個記憶體晶片中， 這個記憶體晶片在沒有通電時也能夠將資料記錄下來，那就是唯讀記憶體(Read Only Memory, ROM)。
  • BIOS對於個人電腦來說是非常重要的， 因為他是系統在開機的時候首先會去讀取的一個小程式
  • 由於磁碟盤是圓的，並且透過機器手臂去讀寫資料，磁碟盤要轉動才能夠讓機器手臂讀寫。因此，通常資料寫入當然就是以圓圈轉圈的方式讀寫囉！ 所以，當初設計就是在類似磁碟盤同心圓上面切出一個一個的小區塊，這些小區塊整合成一個圓形，讓機器手臂上的讀寫頭去存取。 這個小區塊就是磁碟的最小物理儲存單位，稱之為磁區 (sector)，那同一個同心圓的磁區組合成的圓就是所謂的磁軌(track)。 由於磁碟裡面可能會有多個磁碟盤，因此在所有磁碟盤上面的同一個磁軌可以組合成所謂的磁柱 (cylinder)。
  • 原本硬碟的磁區都是設計成 512byte 的容量，但因為近期以來硬碟的容量越來越大，為了減少資料量的拆解，所以新的高容量硬碟已經有 4Kbyte 的磁區設計
  • 拿快閃記憶體去製作成高容量的設備，這些設備的連接界面也是透過 SATA 或 SAS，而且外型還做的跟傳統磁碟一樣
  • 固態硬碟最大的好處是，它沒有馬達不需要轉動，而是透過記憶體直接讀寫的特性，因此除了沒資料延遲且快速之外，還很省電
  • 硬碟主要是利用主軸馬達轉動磁碟盤來存取，因此轉速的快慢會影響到效能
  • 使用作業系統的正常關機方式，才能夠有比較好的硬碟保養啊！因為他會讓硬碟的機械手臂歸回原位啊！
  • I/O位址有點類似每個裝置的門牌號碼，每個裝置都有他自己的位址，一般來說，不能有兩個裝置使用同一個I/O位址， 否則系統就會不曉得該如何運作這兩個裝置了。
  • IRQ就可以想成是各個門牌連接到郵件中心(CPU)的專門路徑囉！ 各裝置可以透過IRQ中斷通道來告知CPU該裝置的工作情況，以方便CPU進行工作分配的任務。
  • BIOS為寫入到主機板上某一塊 flash 或 EEPROM 的程式，他可以在開機的時候執行，以載入CMOS當中的參數， 並嘗試呼叫儲存裝置中的開機程式，進一步進入作業系統當中。
  • 電腦都只有記錄0/1而已，甚至記錄的資料都是使用byte/bit等單位來記錄的
  • 常用的英文編碼表為ASCII系統，這個編碼系統中， 每個符號(英文、數字或符號等)都會佔用1bytes的記錄， 因此總共會有28=256種變化
  • 中文字當中的編碼系統早期最常用的就是big5這個編碼表了。 每個中文字會佔用2bytes，理論上最多可以有216=65536，亦即最多可達6萬多個中文字。
  • 國際組織ISO/IEC跳出來制訂了所謂的Unicode編碼系統， 我們常常稱呼的UTF8或萬國碼的編碼
  • CPU其實是具有微指令集的。因此，我們需要CPU幫忙工作時，就得要參考微指令集的內容， 然後撰寫讓CPU讀的懂的指令碼給CPU執行，這樣就能夠讓CPU運作了。
  • 編譯器』來將這些人類能夠寫的程式語言轉譯成為機器能看懂得機器碼
  • 當你需要將運作的資料寫入記憶體中，你就得要自行分配一個記憶體區塊出來讓自己的資料能夠填上去， 所以你還得要瞭解到記憶體的位址是如何定位的，啊！眼淚還是不知不覺的流了下來... 怎麼寫程式這麼麻煩啊！
  • 作業系統(Operating System, OS)其實也是一組程式， 這組程式的重點在於管理電腦的所有活動以及驅動系統中的所有硬體。
  • 作業系統的功能就是讓CPU可以開始判斷邏輯與運算數值、 讓主記憶體可以開始載入/讀出資料與程式碼、讓硬碟可以開始被存取、讓網路卡可以開始傳輸資料、 讓所有周邊可以開始運轉等等。
  • 只有核心有提供的功能，你的電腦系統才能幫你完成！舉例來說，你的核心並不支援TCP/IP的網路協定， 那麼無論你購買了什麼樣的網卡，這個核心都無法提供網路能力的！
  • 核心程式所放置到記憶體當中的區塊是受保護的！ 並且開機後就一直常駐在記憶體當中。
  • 作業系統通常會提供一整組的開發介面給工程師來開發軟體！ 工程師只要遵守該開發介面那就很容易開發軟體了！
  • 系統呼叫介面(System call interface)
  • 程序管理(Process control)
  • 記憶體管理(Memory management)
  • 檔案系統管理(Filesystem management)
  • 通常核心會提供虛擬記憶體的功能，當記憶體不足時可以提供記憶體置換(swap)的功能
  • 裝置的驅動(Device drivers)
  • 『可載入模組』功能，可以將驅動程式編輯成模組，就不需要重新的編譯核心
  • 驅動程式可以說是作業系統裡面相當重要的一環
  • 作業系統通常會提供一個開發介面給硬體開發商， 讓他們可以根據這個介面設計可以驅動他們硬體的『驅動程式』，如此一來，只要使用者安裝驅動程式後， 自然就可以在他們的作業系統上面驅動這塊顯示卡了。
  • 張 旭 on 22 Jun 21
     
    "但因為 CPU 的運算速度比其他的設備都要來的快，又為了要滿足 FSB 的頻率，因此廠商就在 CPU 內部再進行加速， 於是就有所謂的外頻與倍頻了。"
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