The Dell Venue 8 Pro is typical of a new class of tablets from Dell, Toshiba, Lenovo, Acer and others offering a full Windows 8.1 environment in an 8 inch form factor, available in the $200 range. This is a perfect size for portable computing and hacking. These devices include Bluetooth 4.0, 802.11n wifi, microSDXC card slot and microUSB OTG connection.
Note: This tutorial does not explain how to use the Arduino on the Windows RT operating system which is not supported software-wise by the Arduino Team. This tutorial discusses using a tablet with the full Intel-based Windows operating system.
You will need a microUSB male OTG to A female cable available from Adafruit and many mobile shops at a reasonable price. This will provide you a full A male connection to plug in a cable to fit your microcontroller. For our Uno example, you would want a standard USB A to B cable (Adafruit sells long and easy to pack short versions).
The good news: Drivers for nearly any Arduino are available for Windows. The bad news: Windows 8.1 really, really hates installing unsigned drivers like those supplied for the Uno by the Arduino team. Some tablets may provide provision to go into recovery and allow unsigned drivers. The procedure to do that is described here. Note this may be nearly impossible with the Dell Venue 8 Pro and other tablets enabling Bitlocker to protect the main drive.
If you cannot use the method above to load the unsigned driver included with the Arduino IDE and until there are signed drivers (which should install "normally"), there is a workaround. This blog post and the accompanying Youtube video go through the steps of loading a signed driver. It installs as a Richochet Wireless USB Modem which is compatible with the Uno.
If you use an Arduino device with FTDI such as Duemilanove or compatibles (NOT UNOs!), there are signed drivers for Windows 8.1 at http://www.ftdichip.com/Drivers/VCP.htm (check your version of Windows 32 or 64 bit in the Control Panel, System option). Yes, these are hacks but easy ones. If the Arduino team publishes a signed driver, the modem hack will no longer be needed. It is discussed in their forums at http://forum.arduino.cc/index.php?topic=205837.0.
You may download the Arduino software (integrated development environment or IDE) from the arduino.cc website. You can alternatively load version 1.05 from Adafruit with built-in support for Flora, Gemma, and Trinket. If you have SD card storage, you may want to install the software to the card to save flash on 32GB tablets.
Once the IDE is installed, click the desktop icon to get to the Windows desktop. Double-click the Arduino icon and you will be in the development environment. Load the included Blink sketch by clicking File then Examples then 01. Basics then Blink. A new window opens with the Blink software sketch.
Ensure your OTG to Uno cable from the previous section is connected from the tablet to the Uno. The Uno should have the power LED on, powered from the tablet. Use an external power supply for the Uno to save tablet battery life. Set the environment for download by clicking Tools, then Board, then select "Arduino Uno" from the list. Go back to the Tools Menu, then Serial Port, then you usually select the last port (COM7 in my case). You can look up which COM port the Arduino uses by opening Control Panel, then "Devices and Printers" then look for the Arduino Uno. If the communications port is not listed, you can right click the icon, select Properties then click the Hardware tab to see which COM port is listed.
Ensure your tablet is connected to the Arduino Uno with the cables noted above. The power light should be lit on the Uno.
To upload the Blink sketch to the Uno, select the right arrow icon. The yellow LED neat the Uno's Pin 13 should now be blinking. The process may take a few seconds longer near the end as the compiled code loads to the Uno.
You can load your own code via a network connection, downloaded from the local flash drive or from a microSD card. When you save programs, I suggest a microSD card as the 32GB flash on the Venue 8 Pro is not a huge amount for a Windows installation (Dell includes Office which bloats the device).