Single board computers (SBC) serve as the motherboard for instrumentation systems including modern PCs. SBCs are composed of a microprocessor, memory chip, and serial and parallel interfaces to communicate with other devices.   Processor or CPU type, processor speed, I/O bus specifications, memory, I/O interfaces, and storage are important specifications to consider when searching for single board computers (SBC).  Additional specifications to consider include chipset type, features and environmental parameters.

Common Bus Choices

Common bus choices for single board computers include ISA or EISA, STD bus, PCI, PMC bus, VME bus, VXI or VMI bus, PXI bus, CompactPCI, Multibus (I&II), PCMCIA (PC card), and PC/104 (PC/104-Plus, EBX, ETX).  A bus is a pathway that is used to transfer data within a computer. This pathway can be established between two or more computer components. There are many types of buses: processor bus, memory bus, AGP bus, etc. The I/O Bus (also known as expansion slots) enables the CPU to communicate with peripheral devices. One important parameter used to measure the performance of a bus is the number of bits at which the bus operates. This is the number of paths (wires) that the bus uses to send data simultaneously. For instance, a 16-bit bus is capable of sending 16 bits of data simultaneously.

Memory Choices

Memory choices for single board computers (SBC) include RAM, cache memory (L1 & L2), flash memory, and CompactFlash^TM.  Random Access Memory (RAM) is the main memory of the computer. The cache contains the data that is accessed most often between the CPU and memory. Cache memory accounts for a small amount of high-speed RAM and is the memory that the processor most often utilizes. The cache runs almost as fast as the processor. Flash memory is a type of RAM that can electronically hold memory even when the power is off. CompactFlash™ is a small, removable mass storage device first introduced in 1994. CompactFlash cards are designed with flash technology; a non-volatile storage solution that retains data indefinitely without a battery even after the system is turned off. These cards are compatible with PCMCIA-ATA standards.

Ports Choices

Ports are physical connectors that allow a peripheral device such as a printer, a keyboard, or modem, to be attached to the computer.  Choices for ports for single board computers (SBC) include serial, parallel, USB and IEEE 1394 (FireWire®).  Communications networks have Local Area Network (LAN) specifications. LAN is a limited-distance high-speed network that supports many hosts (computers).  Choices for communications networks include GPIB (IEEE 488, HPIB), Ethernet, ARCNET, Token Ring, FDDI, ATM, AppleTalk®, AS-I, Interbus-S, Seriplex, CANbus, DeviceNet, PROFIBUS, Foundation Fieldbus (FF), P-Net, WorldFIP, Lon®, HART®, Beckhoff I/O, BITBUS, SDS, and SERCOS.  Additional storage for single board computers can be hard drive, floppy drive, CD-ROM, or tape support.