The Raspberry Pi is a small card size LINUX based computer board designed and intended for students, hobbyists, electronics and computer enthusiasts. It was first released in February 2012 and from then on undergone several developments. The RPi has the capability of most personal computers available in the market except that it has the primary advantage of being configurable for various purposes and applications. It has become very popular for Robotics and Automation experimenters and tinkerers because of its size and low power consumption. It can be customized according to the preference of the user and be operated using an ordinary and commonly available batteries. Power source for RPi is not a problem because it can be powered by regular smartphone charger or using Lithium-Ion or Ni-Cad batteries connected through 5 Volts DC regulator capable of delivering current of atleast 1.5 Amperes.  However, compare to Arduino microcontroller board and the like, Raspberry Pi does not support real time processing. Nevertheless, this limitation did not hinder to the success of RPi's popularity.

There are now ten Raspberry Pi models available in the market excluding the Compute Modules and they are as follows:

1. Model A

2. Model A+

3. Model B

4. Model B+

5. Model Raspberry Pi 2

6. Raspberry Pi Zero

7. Raspberry Pi 3 - with built-in Wi-Fi and Bluetooth

8. Raspberry Pi 3 - Model B

9. Raspberry Pi Zero W - with built-in W-Fi and Bluetooth

10. Raspberry Pi 4

THE OPERATING SYSTEM

There are many software developers and companies that supports the Raspberry Pi. Because of this, users can choose among several Operating Systems as listed here: 

1.  RASPBIAN (Debian)

2.  RISC OS 

3. UBUNTU CORE

4. UBUNTU MATE

5. UBUNTU SERVER

6. LIBREELEC

7. MOZILLA WEB THINGS

8. ICHIGO JAM RPI

9. WINDOWS 10 IOT CORE

10. OSMC

11. PINET

12. RPI ORACLE WEATHER STATION

PROGRAMMING LANGUAGE

Several programming languages exist for the RPi's and mostly included in the Operating System that can be downloaded. Currently, there are two types of GPIO P1 terminal configuration that can be programmed or accessed. The older version has 26 pins and the latest version has 40 pins which provided additional GPIOs.

Below is just some of the programming languages that can be use to control the GPIO terminals.

1. Phyton

2. BBC BASIC    -       RISCOS

3. BBC BASIC    -       Raspbian

4. Return to BASIC

5.  Scratch

6. HTML5

7. JQuery

8. Java

9. JavaScript

10. C Language

11. Perl

12. Erlang

INSTALLING AN OPERATING SYSTEM :

MODEL :   Raspberry Pi Zero W  - with WiFi and Bluetooth 

       I will be using my newly received  Raspberry Pi Zero W model for the purpose of showing the latest  model and explaining the difference between the old models and this latest one.

1. First, prepare a uSD card with atleast a capacity of 8GB or higher (4GB will be fine but i don't

    recommend) and the Standard SD adapter. Insert it on the SD slot  and format using FAT32 on

    your PC Windows Explorer.

2. Download Win32DiskImager.exe if you don't have it yet. This will be use to install a

    non-Windows program from your uSD card. In this case a Raspbian OS image.

3. Download the Raspbian Buster with desktop and recommended software Version July   

     2019 zip file from www.raspberrypi.org using your Android mobile phone (I will explain why

     instead of your PC). The filesize is about 1,945 MB but after the download you might see it

     as 2.26GB filesize on Android smartphone Download folder.

4. Copy the Raspbian Buster OS image from your Android smart phone to a USB Memory

    dongle then from that USB Memory dongle to your PC drive C: Root or just connect your

    Android smartphone to your PC using a USB to USB cable and copy the Raspbian Buster OS

    directly from your Android smartphone Download folder without the need of USB Memory

    dongle.

5. Now, the reason why you may need to download the Raspbian Buster OS using Android

    smartphone is because the Antivirus (Windows Defender) in your PC might drop or block your

   downloading process because it is not a file that will run on Windows and it cannot identify the

   file platform. Windows10 might be identifying it as some kind of virus or malware.  In my case I

   am unsuccessful despite several attempts.  Perhaps you  might be able to download it

   succesfully if  your PC is under Windows XP operating system which I did not try.

6. All set with the two files you need and a formatted uSD. Run Win32DiskImager and browse the

    location of your Raspbian Buster OS image. If Win32DiskImager did not found the Raspbian

    Buster image, then you need to bring-out the file from its folder because Win32DiskImager will

    not see the folder, only the image file. So, copy the image file  or put the image file on the root of

    Drive C:.

7. You should be able to see now the Raspbian Buster image file on the box of the

     Win32DiskImager.  Before pressing the WRITE button ensure that the drive location of your

     uSD card is correct. 

8. Press the WRITE button and wait while the copying is in progress. It may take a while to install

    or copy the Raspbian Buster OS to your uSD card so relax.

9. When the copying is completed, Insert the uSD card onto Raspberry Pi Zero W uSD slot.

10. Insert the HDMI and USB mouse/keyboard adaptors onto Raspberry Pi Zero W and connect

       to one of  the TV HDMI port using a standard HDMI cable.

11. Power your Raspberry Pi Zero W using any Android smartphone 5 Volts DC charger (not C

      Type plug)

12. You should see a steady GREEN light indicating that the Raspbian Buster OS is working and

       loading. Almost immediately, you should see the Raspbian OS Desktop graphics on your TV.

13. Note that your old RF Wireless Keyboard might not  work with this new Raspbian Buster

      Operating System. Luckily I have a  Bluetooth keyboard (as shown here) and a USB wire

      keyboard  that works fine. It is quite strange that the RF Wireless Keyboard did not work on

      this model but works well on other models such as Model A,  B and RPi 2 without any

      problem.

 14. Additionally, I also  I tried to run the Raspbian Wheezy and the old RISCOS on this model but 

       found some compatibility issues. Of course, you cannot connect to WiFi and interface with

       Bluetooth devices because these two Operating Systems  do not have the built-in

       features that will  enable you to connect to internet through WIFI and connect Bluetooth

       devices despite the presence of WiFi and Bluetooth component interface.

 15.  Lastly, don't forget to update the Raspbian Buster installed on your uSD card once you are

       able to connect to internet. Unfortunately, the Raspbian BBC BASIC won't run or open on this

       Raspberry Pi Zero W despite my several attempts to make it work. What surprised me was

       the Raspbian BBC BASIC worked  when I used the same uSD in Raspberry Pi Model 2.  I still

       don't know the reason why at the time of this writing.

NOTE:

       RISCOS BBC Basic and the latest GPIO Module from Tank will not work on Raspberry Pi 2 and higher models as of 12 January 2020 based on my latest attempts.

Use the BBC Basic SDL from Raspbian instead that comes with built-in GPIO interface. RISCOS BBC Basic and Raspbian BBC Basic files are not compatible.

Meaning, you may have to modify some if not all of the text commands or statements in RISCOS BBC Basic program in order to convert it to Raspbian BBC Basic  platform as of today 12 January 2020.

Example of Raspbian BBC Basic Program:

      REM Program to activate 8 relays to switch-ON 8 LEDs

 ACTUAL OPERATION:

GPIO TEST TO ACTIVATE 8 RELAYS TO SWITH-ON 8 LEDs