Raspberry pi zero
Bought some of the Raspberry Pi Zeros for five dollars. Was able to install the standard Raspian image on an mm card and boot up without problem. On the system I used I remotely logged into the Rpi via ssh so that I did not need a monitor. Changed the user password and shut down.
For the image you will need to to use a micro sd card for the image. The raspberry website has all the details how to do that. Used a regular sd card with a micro insert so that the usb to mmccard adapter would easily handle the image to the card.
There are two micro usb ports on the board so that one is for power and the other is for a regular usb connection. They are marked on the board. On the regular usb port, I hooked up an otg cable connected to a usb ethernet adapter. Raspian saw the ethernet adapter without any problem.
As for audio, you have to use the hdmi adapter, though to connect to a regular hdmi cable you will need a mini to standard adapter. So you might as well get hdmi monitor. The old analog and composite ports are no longer available on the rpi zero. Thought there are solder points on the board so you can use discrete parts for analog audio and video.
Try these circuits at your own risk:
Now, as for the bottom two pins, the square one is TX (signal) and the circular one is ground.
The specs say the RPI Zero 1ghz cpu speed. That is only if you overclock the board otherwise it is only 700 mhz, As for the gpio, you will have to do all the soldering your self as there is no header.
All in all for $5 it is a heck of a deal. Just like using most linux boxes. The sky is the limit as there is a tremendous amount of software in the repo.
Suggested circuit for adding a wifi dongle. Use at your own risk.
Also a good usb 2.0 hub and an otg cable makes it easy to add attachments without having to do any soldering. Sometimes nicad batteries can make excellent power sources for the RPi.
Old fashion connection. An otg cable is needed to interface the two.
Little 5 dollar computer hooked up to the tv. doing an update in the background. The rpizero is the new Commodore64
Could put the free Kodi software on it and have another appletv/roku like device for pennies. Need to make a case. An old game machine might work or just a cheap plastic case.