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As they are usually low-cost, and have an especially low capital cost for development, single-board microcontrollers have long been popular in education. They are also a popular means for developers to gain hands-on experience with a new [[processor family]].
== Origins ==
Single-board microcontrollers appeared in the late 1970s, when the appearance of early microprocessors, such as the [[MOS Technology 6502|6502]] and the [[Zilog Z80|Z80]],<ref name="ETI, Marvin" >{{Cite journal
|journal=[[Electronics Today International]]
|title='Marvin' - Z80 Control Computer
|author=Peter Grigson
|author2=David Harris
|date= August–October 1983
}}</ref> made it practical to build an entire controller on a single board, as well as affordable to dedicate a computer to a relatively minor task.
In March 1976, [[Intel]] announced a single-board computer product that integrated all of the support components required for their [[8080]] microprocessor, along with 1 [[kilobyte]] of RAM, 4 kilobytes of user-programmable ROM, and 48 lines of parallel digital I/O with line drivers. The board also offered expansion through a bus connector, but could be used without an expansion card cage when applications did not require additional hardware. Software development for this system was hosted on Intel's [[Intellec MDS]] microcomputer development system; this provided assembler and [[PL/M]] support, and permitted [[in-circuit emulation]] for debugging.<ref>[http://www.dvq.com/docs/brochures/intel_sbc_80_10.pdf Intel SBC 80/10 Single Board Computer brochure], 1976</ref>
Processors of this era required a number of support chips to be included outside of the processor. [[RAM]] and [[EPROM]] were separate, often requiring memory management or refresh circuitry for [[Dynamic random-access memory|dynamic memory]]. I/O processing might have been carried out by a single chip such as the [[Intel 8255|8255]], but frequently required several more chips.
A single-board microcontroller differs from a [[single-board computer]] in that it lacks the general-purpose user interface and mass storage interfaces that a more general-purpose computer would have. Compared to a [[microprocessor development board]], a microcontroller board would emphasize digital and analog control interconnections to some controlled system, whereas a development board might by have only a few or no discrete or analog input/output devices. The development board exists to showcase or train on some particular processor family and, therefore, internal implementation is more important than external function.
== Internal bus ==
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== External bus expansion ==
Some microcontroller boards using a general-purpose microprocessor can bring the address and data bus of the processor to an expansion connector, allowing additional memory or peripherals to be added. This provides resources not already present on the single board system. Since not every system will require expansion, the connector may be optional, with a mounting position provided for installation by
== Input and output ==
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