MCUs

An MCU is basically a computer-on-a-chip. A ``typical'' MCU is the ATMega128 from Atmel. It is available in a TQFP-64 package, as well as a smaller MELF package that is difficult for hand soldering.

To get an MCU working, you just need VCC and ground. In most cases, you don't even need regulated VCC, just some voltage within a fairly wide range (3V to 5V, for example). The I/O pins of an MCU are usually not protected, but we'll talk about that later.

Most modern MCUs store programs in flash and are ISP (in system programmable). This means you only need a 5 to 6 pin connector left open for programming, and have the MCU soldered onto a PCB permanently. Most program flash memory are rated for at least 10,000 erase cycles.

As far as speed is concerned, modern MCUs can have 8 or 16 bit pipelined processors. This often translates to one clock per instruction for most instructions. The clock speed of MCUs ranges from sub-megahertz (for low-power applications) to 20+MHz for performance.

One major drawback of MCUs is the size of internal RAM. Most only come with 8kB or less internal RAM. This is more than sufficient for many applications, including Micromouse robots. However, there are some applications that require more RAM than MCUs can offer.