意(yi)大利GEFRAN控(kong)制(zhi)器基本功(gong)能
數(shù)據(jù)(ju)緩(huan)沖：由於I/O設(shè)備(bei)的速(su)率(lv)較低(di)而(er)CPU和(he)內(nèi)存(cun)的速(su)率(lv)卻很高(gao)，故(gu)在控(kong)制(zhi)器中(zhong)必(bi)須(xu)設(shè)置(zhi)壹緩(huan)沖器。在輸(shu)出時(shí)(shi)，用此緩(huan)沖器暫存(cun)由主(zhu)機(jī)(ji)高速傳來(lai)的數(shù)據(jù)(ju)，然後才(cai)以I/O設(shè)備(bei)所具(ju)有(you)的速(su)率(lv)將(jiang)緩(huan)沖器中的數(shù)據(jù)(ju)傳送給I/O設(shè)備(bei)；在輸(shu)入(ru)時(shí)(shi)，緩(huan)沖器則用於暫存(cun)從I/O設(shè)備(bei)送來(lai)的數(shù)據(jù)(ju)，待接收到(dao)壹批數(shù)據(jù)(ju)後，再(zai)將(jiang)緩(huan)沖器中的數(shù)據(jù)(ju)高速(su)地(di)傳送給主(zhu)機(jī)(ji)。
差(cha)錯(cuò)(cuo)控(kong)制(zhi)：設(shè)備(bei)控(kong)制(zhi)器還(hai)兼(jian)管(guan)對由I/O設(shè)備(bei)傳送來(lai)的數(shù)據(jù)(ju)進(jìn)(jin)行差(cha)錯(cuò)(cuo)檢(jian)測。若發(fā)(fa)現(xiàn)(xian)傳送中(zhong)出現(xiàn)(xian)了錯(cuò)(cuo)誤(wu)，通(tong)常(chang)是(shi)將差(cha)錯(cuò)(cuo)檢(jian)測碼(ma)置(zhi)位，並(bing)向 CPU報(bào)告，於是CPU將本次傳送來(lai)的數(shù)據(jù)(ju)作(zuo)廢，並(bing)重新(xin)進(jìn)(jin)行壹(yi)次傳送。這(zhe)樣(yang)便(bian)可保(bao)證數(shù)據(jù)(ju)輸(shu)入(ru)的正確性。
數(shù)據(jù)(ju)交(jiao)換：這(zhe)是(shi)指(zhi)實(shí)(shi)現(xiàn)(xian)CPU與(yu)控(kong)制(zhi)器之間(jian)、控(kong)制(zhi)器與(yu)設(shè)備(bei)之間(jian)的數(shù)據(jù)(ju)交(jiao)換。對於前者(zhe)，是通(tong)過數(shù)據(jù)(ju)總線，由(you)CPU並(bing)行地(di)把(ba)數(shù)據(jù)(ju)寫入(ru)控(kong)制(zhi)器，或(huo)從(cong)控(kong)制(zhi)器中(zhong)並(bing)行地(di)讀出數(shù)據(jù)(ju)；對於後者(zhe)，是設(shè)備(bei)將數(shù)據(jù)(ju)輸(shu)入(ru)到(dao)控(kong)制(zhi)器，或(huo)從(cong)控(kong)制(zhi)器傳送給設(shè)備(bei)。為此(ci)，在控(kong)制(zhi)器中(zhong)須(xu)設(shè)置(zhi)數(shù)據(jù)(ju)寄存(cun)器。
狀態(tài)(tai)說明：標(biāo)(biao)識和(he)報(bào)告設(shè)備(bei)的狀態(tài)(tai)控(kong)制(zhi)器應(yīng)(ying)記(ji)下(xia)設(shè)備(bei)的狀態(tài)(tai)供(gong)CPU了解。例(li)如(ru)，僅當(dāng)(dang)該設(shè)備(bei)處(chu)於發(fā)(fa)送就緒(xu)狀態(tài)(tai)時(shí)(shi)，CPU才(cai)能(neng)啟(qi)動控(kong)制(zhi)器從(cong)設(shè)備(bei)中讀出數(shù)據(jù)(ju)。為此(ci)，在控(kong)制(zhi)器中(zhong)應(yīng)(ying)設(shè)置(zhi)壹狀態(tài)(tai)寄存(cun)器，用(yong)其中(zhong)的每(mei)壹(yi)位(wei)來(lai)反(fan)映(ying)設(shè)備(bei)的某(mou)壹(yi)種(zhong)狀態(tài)(tai)。當(dāng)(dang)CPU將該(gai)寄存(cun)器的內(nèi)容讀入(ru)後，便(bian)可了解該(gai)設(shè)備(bei)的狀態(tài)(tai)。
接收和(he)識別命(ming)令：CPU可(ke)以向控(kong)制(zhi)器發(fā)(fa)送多(duo)種(zhong)不同(tong)的命(ming)令，設(shè)備(bei)控(kong)制(zhi)器應(yīng)(ying)能(neng)接收並(bing)識別這(zhe)些(xie)命(ming)令。為(wei)此，在控(kong)制(zhi)器中(zhong)應(yīng)(ying)具(ju)有(you)相應(yīng)的控(kong)制(zhi)寄存(cun)器，用(yong)來(lai)存(cun)放接收的命(ming)令和(he)參數(shù)，並(bing)對所接收的命(ming)令進(jìn)(jin)行譯(yi)碼(ma)。例(li)如(ru)，磁盤(pan)控(kong)制(zhi)器可(ke)以接收CPU發(fā)(fa)來(lai)的Read、Write、Format等(deng)15條(tiao)不(bu)同(tong)的命(ming)令，而(er)且(qie)有(you)些(xie)命(ming)令還(hai)帶有(you)參數(shù)；相應(yīng)地，在磁盤(pan)控(kong)制(zhi)器中(zhong)有(you)多(duo)個(gè)寄存(cun)器和(he)命(ming)令譯(yi)碼(ma)器(qi)等。
地址識別：就(jiu)像內(nèi)存(cun)中的每(mei)壹(yi)個(gè)(ge)單(dan)元(yuan)都有(you)壹(yi)個(gè)(ge)地址壹(yi)樣(yang)，系統(tǒng)(tong)中(zhong)的每(mei)壹(yi)個(gè)(ge)設(shè)備(bei)也(ye)都有(you)壹(yi)個(gè)(ge)地址，而(er)設(shè)備(bei)控(kong)制(zhi)器又(you)必(bi)須(xu)能(neng)夠(gou)識別它所控(kong)制(zhi)的每(mei)個(gè)(ge)設(shè)備(bei)的地(di)址(zhi)。此(ci)外，為使CPU能向(xiang)(或(huo)從(cong))寄存(cun)器中(zhong)寫入(ru)(或(huo)讀出)數(shù)據(jù)(ju)，這些(xie)寄存(cun)器都應(yīng)(ying)具有(you)*的地(di)址(zhi)。
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