The Propeller is a microcontroller from Parallax Inc.
What makes it different is that it is based around eight 'cogs' - each capable of working independently but kept in synch by the 'hub' that clocks each in turn. Cogs can share information between them. The use of separate cogs means no interrupts and the dedication of resources to tasks on a continuous basis.
Each of the cogs is capable of generating TV / VGA video.
There are 32 I/O pins that are not allocated in any way (apart from those used to upload software). They can be used for whatever is required.
Need an RS232 connection? Get the object from the Obex library, allocate the pins and away you go.
Need four serial outputs? No problem.
Need to use SPI? Grab the SPI object, allocate the pins and away you go.
Need to drive LEDs? No problem.
Need to have a serial input, SPI interface and a video output? Easy.
Simple ADC? Easy.
The sub-pages detail some of the uses to which I have put the Prop - it really is very, very good.