Why doesn't anyone make a real PC with GPIOs? I am sure there are at least a few hackers out there who would be interested but if you want real high speed GPIOs you need either expensive hardware like a special card from National instruments or a low powered single board computer like Pi, Edison or a gumstix. I would love for Intel to breakout a nice 20 pin header on some of their boards.
On sufficiently old/industrial PCs, the parallel port is a pretty usable GPIO header, especially the more modern implementations with bi-directional pins.
It's easy to use one to switch a transistor[1], for instance, and there is a Python library to control the port[2]. An optoisolator is a good idea since computers are expensive and isolation is cheap.
The DonglePi looks nice since it will exposes I2C, SPI, and PWM. I could see it being handy to test out I2C and SPI parts before integrating them into custom boards.
