Tom Barrett, David Lunnev. Alger D. sait; and Marc Walter East Carolina Universitv Greenville, North Carolina 27834
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A simple and instructive experiment in interfacing
Although a number of experiments have been described i n
this J o u r n a l involving t h e use of laboratory minicomputers ( 1 5 ) , a t the time of this writing n o articles have appeared here which describe exneriments w i n e microcomnuters. T h i s is unt'urtunate hecauw s w r r d inexpensive rnicruconiputers are now available which could 1,e adapted readily tt) the tearhinr of computer interfacing a t a n absolute minimum of cost. T h e recent proliferation of microcomputer systems is i n p a r t responsihle for t h e dearth of published experiments which utilize them. T h e r e are dozens of microprocessors now available which have been emhodied i n hundreds of different microcomputers; they vary widely in their input-output capabilities and they speak a veritable Babel of languages. Because of this some of t h e best instructional materials on microprocessors a r e tied so closelv t o narticular manufacturers' hardware t h a t t h e experimedts can h e adapted to other machines only with considerable difficultv ( 6 ) . However, there a r e simple a d d instructive interfacing experiments t h a t can h e performed on a n v microcomnuter possessing adequate memory a n d input-o"tput facilities; i t is our intention t o describe here such a n experiment, a n d to descrihe i t i n such a way a s t o make i t independent of t h e part,icular machine being used.
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Computer Requirements Thr m~nimumnrcr-qary requirements for perfmiming this rxpcrimtnt with n m r n n m p u r r r arc that the machinep
