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A single board computer is a computer where all processing, memory and input output functionality is provided on one circuit board. This differs form a mother/daughter configuration by being specialized for a particular purpose. Random access memory, processing and input/output are all customized for a specific purpose. Mother boards, on the other hand are generally standardized and mass produced.

The first example of this type of computer was knows as the dyna-micro. It was powered by a c8080a processor and memory, called eprom made by Intel. This kind of read only memory was erasable with ultra-violet light. The eprom chip had a translucent pane over the memory so that it could be erased.

This original SBC was renamed the MMD-1. Such machines were pivotal in the development of the personal computer. The devices were central to the kinds of home computer clubs that Steve Jobs, Steve Wozniak and other early pioneers were involved with.

Single board computers can come with or without expansion slots. Typically, SBCs without slots are generally used in applications where the device has a single use. Examples are video poker, slot machines or machine control computers. Such SBCs are tailored specifically for the task the machine was designed for. Processing, input/output and memory are specific to the machine's needs. As such, these SBCs are more efficient and lighter than a comparable mother/daughter computer would be.

In some cases, SBCs can provide memory and processing for a back-plane. These devices have any number of ports connected in parallel, but no memory or processing. An SBC can be connected to the back-plane to provide the necessary horsepower. These arrangements can be more stable than a generic motherboard connected to its peripherals by cables.

In a mother/daughter configuration, the advantage is that they are universal and can be used for many different kinds of applications. As such, they can be produced in great numbers and therefore much more inexpensively. SBCs are customized and can be made to fit perfectly. They can also be made for obsolete standards such as ISA. Consequently, they are more expensive to produce, but may be more effective and efficient over time.

To summarize, single board computers are circuit boards with processors and memory, that are generally made for a specific purpose. They are tailored for a particular job and as such have the requisite memory, processing and input/output that the application demands. They can also be used to supply processing power for a back-plane.