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The History of Single Board Computers

October 29, 2009

So what is a single board computer and how did it come to be? A single board computer is any electronic system with at least a microprocessor, memory and I/O that fits on a single circuit board.

board

SOM - System on Module SBC

In the beginning computers were based on vacuum tubes, but they were hardly single board computers–in fact, they often took up entire rooms.

As technology progressed, single logic gates were small enough to put on a single board. (They were made of discrete components and transistors.)

Companies such as Digital Equipment Corporation and TI provided these logic functions on a board. These boards were in turn combined to create the basic functional units of computers such as the Arithmetic Logic Unit (ALU), Central Processing Unit (CPU) etc.

It was not until integrated circuits for memory and microprocessors were available that a true single board computer was possible. Early single board computers comprised systems like the original Mini-micro designer (based on the intel 8080)  and later the Apple computer (6502) and the TRS-80 (Z80 based).

Modern single board computers come in three types:

  1. Stand-alone systems – like ATX mother board based systems
  2. OEM single board computers – designed to be integrated into a product, including SOMs or Systems on Modules
  3. Evaluation systems – used as prototype systems that allow embedded systems engineers to develop software before their custom hardware is ready.

Single board computers can be used in bus and rack based systems. Typical busses include:

  • Advanced TCA
  • Multibus
  • Compact PCI, C PCI
  • PXI
  • Embedded Compact Extended (ECX)
  • Micro – Tca
  • Mini-ITX
  • VME Bus
  • PC/104
  • PICMG
  • STD Bus
  • VPX
  • VXI

In later posts we will cover these Bus structures in more detail.

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