GPIO - General Purpose Input Output
"PI GPIO reference board on a Rasperry Pi Rev 1" by Low Voltage Labs is licensed under CC BY-SA 2.0
A powerful feature of the Raspberry Pi is the row of GPIO (general-purpose input/output) pins along the top edge of the board. A 40-pin GPIO header is found on all current Raspberry Pi boards (unpopulated on Pi Zero and Pi Zero W). Prior to the Pi 1 Model B+ (2014), boards comprised a shorter 26-pin header. Any of the GPIO pins can be designated (in software) as an input or output pin and used for a wide range of purposes.
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Holy Grail CSS Layout
"File:HolyGrail.svg" by David Lark is licensed under CC BY-SA 4.0
Holy Grail is a layout pattern that’s very common on the web. It consists of a header, a main content area with fixed-width navigation on the left, content in the middle and a fixed-width sidebar on the right and then a footer.
It is commonly desired and implemented, but for many years, the various ways in which it could be implemented with available technologies all had drawbacks. Because of this, finding an optimal implementation was likened to searching for the elusive Holy Grail.
Below example is taken from In Search of the Holy Grail
<div id="header"></div><div id="container">
<div id="center" class="column"></div>
<div id="left" class="column"></div>
<div id="right" class="column"></div></div><div id="footer"></div>body {
min-width: 550px; /* 2x LC width + RC width */
}
#container {
padding-left: 200px; /* LC width */
padding-right: 150px; /* RC width */
}
#container .column {
position: relative;
float: left;
}
#center {
width: 100%;
}
#left {
width: 200px; /* LC width */
right: 200px; /* LC width */
margin-left: -100%;
}
#right {
width: 150px; /* RC width */
margin-right: -150px; /* RC width */
}
#footer {
clear: both;
}
/*** IE6 Fix ***/
* html #left {
left: 150px; /* RC width */
}References:
Scratch on Raspberry Pi
"Design Challenge - Remix Jetpack Girl" by ScratchEdTeam is licensed under CC BY 2.0
Scratch is a visual programming tool which allows the user to create animations and games with a drag-and-drop interface. It allows you to create your own computer games, interactive stories, and animations using some programming techniques without actually having to write code. It’s a great way to get started programming on the Raspberry Pi with young people.
The version of Scratch included with the Raspberry Pi has a number of unique features; one of the most useful is its ability to communicate with the GPIO pins (General Purpose Input Output). These pins allow you to connect your Raspberry Pi to a range of devices, from lights and motors to buttons and sensors.
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Essential Raspberry Pi accessories
Essential accessories to get started with Raspberry Pi.
"Raspberry-Pi-Model-B-top-with-labels" by mariawebideas is licensed under CC BY 2.0
Power Supply
To connect to a power socket, all Raspberry Pi models have a USB port (the same found on many mobile phones): either USB-C for Raspberry Pi 4, or micro USB for Raspberry Pi 3, 2 and 1.
MicroSD card
Your Raspberry Pi needs an SD card to store all its files and the Raspbian operating system.
A keyboard and a mouse
To start using your Raspberry Pi, you need a USB keyboard and a USB mouse.
A TV or computer screen
To view the Raspbian desktop environment, you need a screen, and a cable to link the screen and the Pi.
HDMI
The Raspberry Pi has a HDMI output port that is compatible with the HDMI port of most modern TVs and computer monitors.
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What is Raspberry Pi?
The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. It’s capable of doing everything you’d expect a desktop computer to do, from browsing the internet and playing high-definition video, to making spreadsheets, word-processing, and playing games.
"P1230070" by macgyverapi is licensed under CC PDM 1.0
The Raspberry Pi operates in the open source ecosystem: it runs Linux (a variety of distributions), and its main supported operating system, Raspberry Pi OS (formerly Raspbian), is open source and runs a suite of open source software. The Raspberry Pi Foundation contributes to the Linux kernel and various other open source projects as well as releasing much of its own software as open source.