larmdevicesAbasicfiredetectionsystemconsistsoftwoparts,detectionandannunciation.Anautomaticdetectiondevice,suchasaheat,smokeorflamedetector,ultravioletorinfrareddetectorsorflameflicker,isbasedondetectingthebyproductofacombustion.Smokedetectors,ofbothionizationandopticaltypes,arethemostcommonlyuseddetectordevices.Whenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreasesfromtheedtotakeadvantageofthesechanges.Inrecentyears,VLSItechnologyhasbeenadvancingatanexponentialrate.FirstNMOSand,inthelastyearortwo,CMOSchipshavebeenproducedwiththesamepackingdensitywithmoregatesperchipyetatalowerpowerconsumptionthanNMOS.Surelythischangeintechnologymustaffectourdesignofhardwareatboththechipandthesystemlevel.Atthechiplevel,singlechipsarenowbeingproducedwhichareequivalenttoboardlevelsofonlythepreviousyearortwo.Thesechipshavemicroprocessor,memoryinRAMandROM,IOPortsbothserialandparallel