【正文】 l y d e v i c e w hi c h c a n o p e r a te i n a mi c r o p r oc ess or mo d e b y us i ng s o me o f the i np ut/ o utp ut l i ne s a s a n a d d r e ss a nd d a ta b us fo r a c c e ss ing e xte r na l me mo r y. T hi s typ e o f d e v i c e c a n b e ha ve func ti o nall y a s the si ngle c hi p mi cro co mp ute r fr o m w hic h i t is deri ve d al bei t w i th r e s tr icte d I/ O a nd a mo d i fi e d e xte r na l c i r c uit. T he us e o f the s e d e v i c es i s c o mmo n e v e n i n p r o d uc ti o n c i r c uits w he r e the v o l ume d o e s no t j us ti fy t he d ev elo p me nt c os ts o f c us to m o n c hi p R O M[ 2] 。 外文原文 A: Fundamentals of Singlechip Microputer T he s i ngl e chi p mi c r o c o mp ute r i s the c ul mi na ti o n o f b o th the d e v e l op me nt o f the d i gi ta l c o mp ute r a nd the i nte gr a te d c i r c uit a r gua b l y the to w mo s t s i gni fi c a nt i nv e nti o ns o f the 2 0 th c e ntur y [ 1 ] . T he s e to w typ e s o f a r c hi te ctur e a r e fo und i n s i ngl e chi p mi c r o c o mp ute r. S o me e mp l o y the s p l i t p r o gr a m/ d ata me mo r y o f the H a r vard a r c hi te ctur e, s ho w n i n F i g. 3 5A1 , o the r s fo l l o w the p hi l o s o phy, w i d e ly a d a p te d fo r ge ne r a l pur p ose c o mp ute r s a nd mi c r o p r o ces so r s, o f ma ki ng no l o gi c a l d i s tinc tio n b e tw e en p r o gr a m a nd d a ta me mo r y a s i n the P r i nc e to n a r c hi te ctur e, s ho w n i n F i g. 3 5A2. In ge ne r a l te r ms a s i ngl e c hip mi c r o c omp ute r i s c ha r a c te rize d b y the i nc o r p o ra tion o f a l l the uni ts o f a c o mp ute r i nto a s i ngl e d e v i c e, a s s ho w n i n F i g3 5A 3. A Harvard type . A conventional Princeton puter Program memory Data memory CPU Inputamp。 Output unit memory CPU Inputamp。ther e ca n s till b e a s i gni fi c ant s a v i ng i n I/ O a nd o the r c hi p s c o mp a r e d to a c o nv e nti o na l mi c r o p r oc ess or b a s e d c i r cui t. Mo r e e xa c t r e p l ac eme nt fo r R O M d e v i c es c a n External Timing ponents System clock Timer/ Counter Serial I/O Prarallel I/O RAM ROM CPU b e o b ta i ne d i n the fo r m o f v a r i ants w i th 39。 E P R O M( E ra sa ble p r o gr a mma b l e R O M ) s o c ke ts o r d e v i c es w i th E P R O M i ns te a d o f R O M 。 i t i s unne c e s s a r y to ma ke d i s ti nc tion b e tw e e n R A M a nd p r o c e sso r r e gi s ter a s i s d o ne i n the c a s e o f a mi c r o p ro ce sso r s ys te m s i nc e R A M a nd r e gi s te rs a r e no t us ua l l y p hys i c a ll y s e p a ra ted i n a mi c r o c o mp ute r . Central processing unit (CPU).T he C P U i s muc h l i ke tha t o f a ny mi c r o p r oc ess or. Ma ny a p p l i cati ons o f mi c r o c o mp ute r s a nd mi c r o c o ntro ller s i nv o l v e the ha nd l i ng o f b i na r y c od ed d e c i ma l ( B C D ) d a t a ( fo r nume r i c a l d i s p la ys , fo r e xa mp l e ) , he nc e i t i s c o mmo n to fi nd tha t the C P U i s w e l l a d a p te d to ha nd l i ng thi s typ e o f d a ta . It i s a l s o c o mmo n to fi nd go o d fa c i l itie s fo r te s ti ng, s e tti ng a nd r e s e tting i nd i v i d ual b i ts o f me mo r y o r I/ O s i nc e ma ny c o ntr o l le r a p p l icati ons i nv o l ve the tur ni ng o n a nd o ff o f s i ngl e o utp ut li nes or the re adi ng the si ngl e li ne. T hese l i ne s ar e rea dil y i nte r fac ed to tw os ta te devi ce s s uc h a s sw i tc hes , ther mo s ta ts , sol id s ta te r ela ys, val ves , mo to r, e tc . Parallel input/output. P a r a llel i np ut a nd o utp ut s c he me s v a r y s o mew ha t i n differ e nt micr oc o mp uter 。 s a nnua l P LC te c hno l o gy up d a te , w e q ue r i e d P LC ma ke r s o n the s e to p i c s a nd mo r e . Programming languages H i ghe r l e v e l P LC p r o gr a mmi ng l a ngua ge s ha v e b e e n a r o und fo r s o me ti me , b ut l a te l y the i r p o p ul a rity ha s mus hr o o mi ng. A s R a ymo nd Le v e i l le, v i c e p r e s id ent amp。A uto ma ti o n . i nc 。 s v e r y d i ffi c ult to w r i te a tr i go no me tr i c func ti o n us i ng l a d d e r l o gi c . La ngua ge s ga i ni ng a c c e p ta nc e i nc l ud e B o o l e an, c o ntr o l s ys te m fl o w c har ting, a nd s uc h func ti o n c ha r t l a ngua ge s a s G r a p hc e t a nd i ts v a r i atio n . A nd the r e 39。 ve go tte n , sa ys K e n Ja nno tta , ma nge r, p r o d uc t p l a nni ng, s e r i es O ne a nd S e r i e s S i x p r o d uc t , a t G E F a nuc N o r th A me r i c a , 39。 s i nc r e a sing us e s uc h i nd us tr i es a s fo o d , c he mi c a l s , a nd p e tr o l eum. Rya n fe e l s the r e a r e tw o typ e s o f a p p l i ca tions i n w hi c h the y39。 s b e i ng a uto ma te d d o e s n39。 v e he a r d a l o t a b o ut MA P i n the l a s t fe w ye a r s , a nd a l o t o f c o mp a ni e s ha v e j ump e d o n the b a nd w a go n. [2 ]Many, ho w e v e r, w e r e d i s a p po inte d w he n a ful l y d e fi ne d a nd c o mp l e te d MA P s p e c i fica tion d i d n39。[ 3 ]b ut F r a nk N e w b ur n, v i c e p r e s id ent o f O mr o n39。s P LCs d o n39。 s unl i ke l y tha t a n i nd i v i dua