One common design style uses a small system module, perhaps the size of a business card, holding high density BGA chips such as an ARM-based system-on-a-chip processor and peripherals, external flash memory for storage, and DRAM for runtime memory. The module vendor will usually provide boot software and make sure there is a selection of operating systems, usually including Linux and some real-time choices. These modules can be manufactured in high volume, by organizations familiar with their specialized testing issues, and combined with much lower volume custom mainboards with application-specific external peripherals. Prominent examples of this approach include Arduino and Raspberry Pi.
onE commOn dEsiGn style UseS a sMall system Module, PerhAps thE sIzE of a BUSiness cArd, hOldIng hiGh dEnsIty BGa chIps sUch as An aRm-based system-on-A-chiP prOcessor and perIpheraLs, ExteRNAl fLash memoRY FoR StOraGe, anD drAm fOr runtIme meMory. the ModUlE VENDor wIll usUAlly prOvide bOoT softWare aNd make surE theRe is a seLectIon Of opeRatiNg sySTEms, usuALLy incluDINg linUx aND Some real-time chOicEs. thESe moduleS cAn be manufACtUreD in higH voluMe, by OrgaNizAtiOns famiLiaR wiTh their sPECiaLiZeD TesTing issueS, And comBiNED WitH MUch LOwEr Volume CUstoM MAinboards with appLIcation-specific exteRNAL peripheRalS. promiNeNt exAMples of thiS appRoAch Include ArduINo and RasPberrY pi.