2/15/2008 Pro g ra mming Anno unc e me nts FIT100 FIT100 FIT100 - PDF document

2/15/2008 Pro g ra mming Anno unc e me nts FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Why is pro g ra mming fun? • No c la sse s a t UW o n Mo nda y ∗ Pre side nt’ s Da y • F ina lly, the re is the de lig ht o f wo rking in suc h a tra c ta b le me dium. T he pro g ra mme r, like the • Se e the c o urse c a le nda r fo r upda te s • Se e the c o urse c a le nda r fo r upda te s po e t, wo rks o nly slig htly re -mo ve d fro m pure t k l li htl d f to re a ding s tho ug ht-stuff. He b uilds his c a stle s in the a ir, fro m a ir, c re a ting b y e xe rtio n o f the • Ne w e xtra -c re dit la b 9 ha s b e e n ima g ina tio n. F e w me dia o f c re a tio n a re so linke d fle xib le , so e a sy to po lish a nd re wo rk, so re a dily c a pa b le o f re a lizing g ra nd c o nc e ptua l • T W la b s fo r the ne xt two we e ks: struc ture s. wo rk o n pro je c ts, whic h a re due o n Source: Frederick P. Brooks, Jr. The Mythical Man-Month Essays on We dne sda ys a t 11pm. Software Engineering. I nstruc tio n E xe c utio n E ng ine s FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Wha t c o mpute rs c a n do ∗ Pe rfo rm o r e xe c ute instruc tio ns to pro c e ss F o llo wing I nstruc tio ns info rma tio n • T T he c o mpute r must ha ve instruc tio ns to fo llo w he c o mpute r must ha ve instruc tio ns to fo llo w Princ iple s o f Co mpute r Ope ratio n, o r H o w Co mpute rs Short list! Wo rk 9-4 I nstruc tio n E xe c utio n Ana to my o f a Co mpute r E ng ine s FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Wha t c o mpute rs c a n't do • Co mpute rs ha ve five b a sic pa rts o r sub syste ms ∗ Me mo ry, c o ntro l unit, a rithme tic / lo g ic unit ∗ Ha ve no ima g ina tio n o r c re a tivity (AL U), input unit, o utput unit ∗ Ha ve no intuitio n ∗ Ha ve no se nse o f iro ny, sub tle ty, pro po rtio n, de c o rum, o r humo r ∗ Are no t vindic tive o r c rue l ∗ Are no t purpo se ful Long list! ∗ Ha ve no fre e will ∗ Re c e nt mo vie s: T e rmina to r, Ma trix, AI 9-5 9-6 1

2/15/2008 Byte -Size Me mo ry Me mo ry L o c a tio n FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Me mo ry sto re s the pro g ra m running a nd the • A c o mmo nly use d dia g ra m o f c o mpute r da ta o n whic h the pro g ra m o pe ra te s me mo ry re pre se nts the disc re te lo c a tio ns a s b o xe s (1 b yte e a c h). • Pro pe rtie s o f me mo ry: • Addre ss o f lo c a tio n is displa ye d a b o ve ∗ Disc re te lo c a tio ns—1 b yte pe r lo c a tio n! the b o x. ∗ Addre sse s—F o r e ve ry me mo ry lo c a tio n (b yte ) • Va lue o r c o nte nts o f lo c a tio n is sho wn in • who le numb e rs sta rting with ze ro the b o x. ∗ Va lue s—Me mo ry lo c a tio ns sto re va lue s. ∗ F inite c a pa c ity—L imite d size —d a ta ma y no t "fit" in the me mo ry lo c a tio n. • Ove rflo w c o nditio ns, b uffe r o ve rruns 9-7 9-8 Ra ndo m Ac c e ss Me mo ry Me mo ry (c o nt'd) (RAM) FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • 1-b yte me mo ry lo c a tio ns c a n sto re • "Ra ndo m a c c e ss" me a ns the c o mpute r c a n re fe r to (a c c e ss) the me mo ry o ne ASCI I c ha ra c te r, o r a numb e r lo c a tio ns in a ny o rde r le ss tha n 256 (0 - 255) • Ofte n me a sure d in • Pro g ra mme rs use a se q ue nc e o f me g a b yte s (MB) – millio ns o f b yte s o r me mo ry lo c a tio ns to g e the r, ig no ring g ig a b yte s (GB) – b illio ns o f b yte s the fa c t tha t the y a ll ha ve diffe re nt • L a rg e me mo ry is pre fe ra b le b e c a use a ddre sse s the re is mo re spa c e fo r pro g ra ms a nd ∗ Blo c ks o f fo ur b yte s a re use d a s a unit da ta (whic h usua lly e q ua te s to le ss I / O) so fre q ue ntly tha t the y a re c a lle d 9-9 9-10 me mo ry "wo rds" Co ntro l Unit FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • I ts c irc uitry fe tc he s a n instruc tio n fro m me mo ry, de c o de s the instruc tio n, a nd fe tc he s the o pe ra nds use d in it ∗ A typic a l instruc tio n mig ht ha ve the fo rm yp g ADD 4000, 2000, 2080 op dest, sr c1, sr c2 ∗ T his instruc tio n a sks tha t the numb e rs sto re d in lo c a tio ns 2000 a nd 2080 b e a d d e d to g e the r, a nd the re sult sto re d in lo c a tio n 4000 [4000] = [2000] + [2080] ∗ Da ta / Ope ra nd F e tc h ste p must g e t the se two va lue s a nd a fte r the y a re a dde d, Re sult Re turn/ Sto re ste p will sto re the a nswe r in lo c a tio n 4000 9-11 9-12 2

2/15/2008 Arithme tic / L o g ic Unit I nput Unit a nd Output Unit (AL U) (I / O) FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Pe rfo rms the ma th • T he wire s a nd c irc uits thro ug h whic h ∗ A c irc uit in the AL info rma tio n mo ve s into a nd o ut o f a U c a n a d d two numb e rs c o mpute r ∗ Othe r c irc uits do multiplic a tio n, c o mpa riso ns, e tc . • I nstruc tio ns tha t just tra nsfe r da ta usua lly do n't i j f • Pe riphe rals use the AL U ∗ Co nne c t to the c o mpute r input/ o utput po rts. • Da ta / Ope ra nd F e tc h ste p o f the Cyc le g e ts the ∗ No t c o nside re d pa rt o f the c o mpute r, b ut va lue s tha t the AL U ne e ds to wo rk o n (o pe ra nd s) spe c ia lize d g a dg e ts tha t e nc o de o r de c o de • Afte r the AL U c o mple te s a n o pe ra tio n, the info rma tio n b e twe e n the c o mpute r a nd the a nswe r is mo ve d fro m the AL U to the de stina tio n physic a l wo rld. me mo ry a ddre ss spe c ifie d in the instruc tio n • Mo de ms, mo nito rs, sc a nne rs, printe rs, ke yb o a rd, ∗ ta xDue = ta xRa te [WA] * sub to ta l; mo use , dig itizing pa d, mic , spe a ke rs 9-13 9-14 A De vic e Drive r fo r T he Pe riphe ra ls E ve ry Pe riphe ra l FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • K e yb o a rd e nc o de s ke ystro ke s we type • "Dumb " de vic e s pro vide b a sic physic a l into b ina ry fo rm fo r the c o mpute r tra nsla tio n to o r fro m b ina ry sig na ls. • Mo nito r de c o de s info rma tio n fro m the • Additio na l info rma tio n fro m the c o mpute r c o mpute r's me mo ry a nd displa ys it o n a is ne e de d to ma ke it o pe ra te inte llig e ntly. lig hte d, c o lo re d sc re e n • e .g ., c o mpute r re c e ive s info rma tio n tha t • Disks drive s a re use d fo r b o th input a nd use r type d shift a nd w a t the sa me time . I t o utput—sto ra g e de vic e s whe re the c o nve rts to a c a pita l W. T he so ftwa re tha t c o mpute r puts a wa y info rma tio n whe n it c o nve rts is c a lle d the de vic e drive r. is no t ne e de d, a nd c a n re trie ve fro m whe n it is ne e de d a g a in 9-15 9-16 Bra nc h a nd T he Pro g ra m Co unte r: T he Pc 's PC Jump I nstruc tio ns FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Ho w do e s the c o mpute r de te rmine whic h ste p • T he instruc tio n ma y inc lude a n to e xe c ute ne xt? a ddre ss to g o to ne xt. T his c ha ng e s • Addre ss o f the ne xt instruc tio n is sto re d in the the PC, so inste a d o f g o ing to PC +4 Co ntro l Unit in the pro gram c o unte r (PC). Co ntro l Unit in the pro gram c o unte r (PC) a uto ma tic a lly, the c o mpute r "jumps" t ti ll th t "j " • Be c a use instruc tio ns use 4 b yte s o f me mo ry, the o r "b ra nc he s" to the spe c ifie d ne xt instruc tio n must b e a t PC + 4, 4 b yte s furthe r lo c a tio n. a lo ng in the se q ue nc e (in g e ne ra l). • Co mpute r a dds fo ur to the PC, so whe n the F / E Cyc le g e ts b a c k to I nstruc tio n F e tc h ste p , the PC is "po inting a t" the ne xt instruc tio n. 9-17 9-18 3

2/15/2008 I nstruc tio n I nte rpre ta tio n FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Pro c e ss o f e xe c uting a pro g ra m ∗ Co mpute r is inte rpre ting o ur c o mma nds, b ut in its o wn la ng ua g e • Be fo re the F / E Cyc le b e g ins, so me o f the me mo ry lo c a tio ns a nd the PC a re visib le in the c o ntro l unit 9-19 9-20 T he F e tc h/ E xe c ute Cyc le Anima tio n FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • A five -ste p c yc le : • F e tc h/ E xe c ute Cyc le 1. I nstruc tio n F e tc h (I F ) 2 2. I I nstruc tio n De c o de (I nstruc tio n De c o de (I D) D) 3. Da ta F e tc h (DF) / Ope ra nd F e tc h (OF ) 4. I nstruc tio n E xe c utio n (E X) 5. Re sult Re turn (RR) / Sto re (ST ) 9-21 Ho w I mpo rta nt is Clo c k Cyc ling the F / E Cyc le Spe e d? FIT100 FIT100 FIT100 FIT100 FIT100 FIT100 • Co mpute rs g e t the ir impre ssive • Mo de rn c o mpute rs try to sta rt a n instruc tio n o n e a c h c lo c k tic k c a pa b ilitie s b y e xe c uting ma ny o f • Pa ss o ff finishing instruc tio n to o the r c irc uitry the se simple instruc tio ns pe r se c o nd ( pipe lining ) ( pipe lining ) ∗ F ive instruc tio ns c a n b e in pro c e ss a t the sa me time • T he Co mpute r Clo c k: De te rmine s • Do e s a 1 GHz c lo c k re a lly e xe c ute a b illio n ra te o f F / E Cyc le instruc tio ns pe r se c o nd? ∗ Me a sure d in g ig a he rtz (GHz), o r b illio ns ∗ No t a pre c ise me a sure me nt. Co mpute r ma y no t b e a b le to sta rt a n instruc tio n o n e a c h tic k, b ut ma y o f c yc le s pe r se c o nd so me time s b e a b le to sta rt mo re tha n o ne instruc tio n a t a time 9-23 9-24 4