We’ve gotten used to the GPIO-available functions of Raspberry Pi computers remaining largely the same over the years, which is why it might have flown a little bit under the radar: the Raspb… ...

The Raspberry Pi 4, on the other hand, is the predecessor of the Raspberry Pi 5. It was released in 2019, just a few months before the world shut down due to COVID-19.

The Raspberry Pi 4-based Computer Module is now available for purchase from $25. ... Instead of the 40 GPIO pins on the Raspberry Pi 4, the Compute Module 4 features 28 GPIO pins, ...

The Raspberry Pi 4’s GPIO header also supports more connections, with UART, SPI, and I2C interfaces each supported on four additional pins, and with fixed support for clock stretching over I2C ...

The Raspberry Pi 400 does feature a horizontal 40-pin GPIO header on the rear of the keyboard, so it's possible to add physical HAT extensions, such as a camera.

With configurable memory amounts, gigabit Ethernet, and dual-display output, the Raspberry Pi 4 is an excellent tiny desktop computer for tinkerers and programming enthusiasts.

Famous in part for its small size, the Raspberry Pi line of inexpensive computers is famously no bigger than a deck of cards, and the Raspberry Pi 4 Model B measures just 3.4 x 2.2 x 0.4 inches.