CU CHUYN V KHOA HC HIN I:
SUPER MICRO COMPUTER

HI SA
Hin nay, my in ton c nhn (Personal Computer, gi tt l PC) ang bnh trܧng v rt thng dng trong ǩi sng hng ngy ca chng ta. Khng nhng th, cng ngy cc loi "chp" vi tnh (micro processor chip) cng ܮc pht trin v thit k ti tn hn, nhanh hn, gn hn, i khi l tt hn xa. Hin nay, c th ni thng dng nht l chp vi tnh "Pentium" ca hng "Intel", v "POWER PC" do hng IBM thit k v phn kin trc v hng "Motorola" sn xut. Ngoi ra, cn nhng chp vi tnh khc nh RISC 700... Cng ngy mi cng vic NJu phi da vo b my in ton, do nng sut ca my cng i hi vo kh nng cung ng ca my. "Super Computer" (My in ton siu ǣng) ܮc thit k nhng s to ln cng knh, v i hi mt mi trܩng ǥc bit cho my hot Ƕng. Vi k thut tn tin, cc k thut gia p dng nhng kin trc thn k ca h thng "super computer" vo chp vi tnh. Tuy khng l bng "super computer" do s khc bit ca k thut mch in, nhng s nh nhn, gn gng khin vic p dng tnh cht "super" vo k nguyn in ton truyn thng, v nhng k thut mang tnh cht "real-time" (thi gian tc thc") ܮc d dng v hu hiu. HS tm gi l nhng h thng "Super Micro-Computer).

T xa, con ngܩi lun lun c khuynh hܧng pht trin Nj tng tin hn cho bt c mt vn NJ g. Trong thp nin 80 va qua, h thng in ton i t nhng b my in ton s qua nhng b my in ton nh nhn nhng li c kh nng khng km g my. Tuy vy, my PC ny vn cha hon ton thay th hn, v ng thi s pht trin k thut mi rt l khin chng ta t hi "vi tin trin ny tng lai h thng my in ton s i ti u?". Tht ra, kh nng ca nhng my in ton ln vn cn l hn nhng b my in ton hin i mi v nh (micro computer), khng nhng th qu trnh hot Ƕng trong mt thi gian di bo m s hu hiu v chnh xc.

Ngy xa, kh nng hot Ƕng ܮc o bng s lܮng thi hnh cc "instructions" (processor codes) trong mt giy ng h. Nhng my in ton ln trang b nhiu "memory", "hardware" c kh nng thi hnh "instruction" vi s lܮng cao, v nhiu "programs" kh khn v phc tp tht mau l ܮc coi nh l mt h thng in ton siu ǣng (super computer). Hai h thng in ton "IBM Stretch" v "Univac LARC" l hai h thng u tin ܮc coi nh "super computer". C hai h thng ܮc thit k v ch to vo cui thp nin 50. Nhng ngy nay c hai h thng ny NJu "v hu" v ܮc thay th bng nhng h thng mau l v hu hiu hn c chc ln.

Trong bn mi nm qua, kh nng thi hnh s lܮng "instructions" (thܩng ܮc o bng n v triu instructions, th d nh 100 Mips; 100 Mega instruction per second) cng gia tng, gn nh gp i mi nm. Ngy nay, my c th chy vi vn tc gn nh c t "instructions" (1000 Mips) trong mt giy ng h. t ljn kh nng , h thng in ton phi nh vo nhng kin trc ǥc bit v tn k trong ngnh in ton. S mau l v ln khng Nj ܮc mnh danh l "Super computer" nh xa na. N i hi h thng phi c kh nng v tc Ƕ hot Ƕng hn c tc Ƕ mch in ca chnh n. Mun ܮc nh vy, nhng kin trc "Parallel processing" (gii tnh song song), "Pipeline processing" (gii tnh dy chuyn) ܮc thit k vo h thng in ton. Nhng h thng ny mi ܮc gi l "super". Chc cc bn khng l g v h thng "Super Computer" mang tn "Cray" Ƕc chim ngi v "super" kh lu. Ngy nay, Nht Bn cng mun tung ra mt h thng "super computer" Nj cnh tranh vi "Cray". Nhng k thut p dng in ton vo cng vic gii tnh hnh nh, video, m thanh Nj nng cao phm cht v cung ng tnh cht "real time" (thi gian tc thc) cn phi c nhng h thng "super" ca my in ton. Nhng nhng h thng"super computer" qu ln, kng knh v cn nhng mi trܩng ǥc bit nh phng lnh vi nhng kin trc cu k Nj dng cho my, do rt bt tin cho vic dng h thng "super computer" ny. l cha k ljn gi c ca my rt cao, v tin ph tn cho my hot Ƕng. V th, nhng kin trc ǥc bit ny ܮc thu gn v p dng vo nhng h thng in ton nh, m chng ta s thy trong tng lai rt gn. l nhng h thng "Super Micro-Computer" s lan trn trong th trܩng in ton.

tm hiu thm v nhng ǥc im thit k "parallel processing" v "pipeline processing", chng ta hy xem qua th d sau. B my vi tnh nh mt th k gip vic s thi hnh mt cng tc do anh giao ph gm nhng li cn dn theo th t ca anh. Th d nh sau:

1) Ly t giy tnh u tin.

2) Bt u t hng th nht.

3) Cng con s ct A vi ct B.

4) Vit kt qu vo ct C, cng hng.

5) Qua hng k.

6) Nu cn hng th tr v li dn s 3 v tip tc.

7) t giy v hp c ghi thng 5.

8) Ly t giy k.

9) Nu cn ghi ngy trong thng 5, tr v li dn s hai v tip tc.

10) Vy l xong, ljn gp ti Nj nhn cng tc mi.

Cng vic trn tng t nh s hot Ƕng ca mt b my vi tnh. Nhng li dn l "instruction", nguyn nhng dn l mt "program". V b my vi tnh s tun t thi hnh t li dn 1 cho ljn 9 cho ti khi xong cng vic. Tc Ƕ thi hnh bnh thܩng do s lanh l ca b my nhng vn b gii hn. tng cܩng s mau l ny, chng ta c th dng hai my vi tnh cng lm vic song song th cng vic c th nhanh hn gp rܫi hoc gn gp i. C l bn rt ngc nhin, v t hi ti sao khng nhanh gp i m t s li thp hn phi khng? T s mau l khng th tnh nh vy ܮc v b ty thuc vo nhiu yu t khc nhau, ngoi cu trc ca h thng, tnh cht cng vic cng nh cch phn chia cng vic cho hai b my, s nh hܪng vo kh nng hot Ƕng ca ton h thng. Ly th d dng hai b my vi tnh Nj thi hnh 10 li dn trn, chng ta s phn chia cng vic ra sao? Gi d hai b my thay phin nhau thi hnh tng li dn. Li dn 1 v 2 khng k v tnh cht sa son (initialize). Nu my A thi hnh li 3 v my B thi hnh li 4, th my B phi ch my A thi hnh xong li 3 mi c kt qu Nj ghi vo ct C theo li 4. V tnh cht lin h ca li 3 v 4 nn my B b ty thuc vo A. l cha k lm th no my B c th nhn ܮc kt qu ca my A. Mun hai my chy song song cng mt lc, chng ta c th phn chia cng vic cho my A lm hng l v my B lm hng chn. Vi li phn vic ny, th hai my khng b ty thuc vo nhau v c th thi hnh cng vic song song vi nhau. Nhng mt tr ngi khc l hai my khng th džc hoc vit ln cng mt t giy cng mt lc ܮc, do ; mt my phi nhܩng cho my kia džc hoc vit trܧc mnh. Mt cch hu hiu khc l hai my ܮc xp dy chuyn (pipe line), tnh cht ny s to ra s xen k l mt my džc th my kia lm tnh. Nh vy, hai my s lm vic song song v lin tc khin t s lm vic s tng ln gn gp i. Bn thy , ch vi vn NJ trong mܩi hng n gin to ra nhng rc ri khng t, hung h mt program phc tp s gy rc ri v kh khn khng bit chng no.

S phn chia, thu gn (theo ngn ng in ton l "optimization") vo cng vic gii tnh song song v dy chuyn khng phi l d Nj t ܮc hu hiu ti a. Khi chuyn dch qua my in ton v dng cc h thng lun l ton hc Nj phn chia cng tc thܩng khng t ܮc s hu hiu ti a. Mun t ܮc s hu hiu ti a cho mi trܩng hp, bn phi t nghin cu v thit k t s bn. y l nhng kh nng ǥc bit ca mi c nhn trong ngnh thit k.

Tuy rng k thut tn k hin i cao nhng khng ܮc trng dng vo nhng cng vic i hi s bo m mt trm phn trm. L do k thut thit k ca nhng b my in ton ln v "software" ca nhng b my ny ܮc coi nh bo m, v khng c "bug" (ch lng cho li lm, lm sai) do qu trnh hot Ƕng lu di ca n. Trong khi , b my PC l v tin li cho c nhn nhng phn thit k c nhng li lm, th d lc chp vi tnh Pentium ca Intel mi ra c "bug" nh thnh thong lm tnh sai, b tnh ton ph (math co-processor) trong chp vi tnh 68040 ca Motorola khng ܮc dng ljn v b "bug". l cha k nhng "bug" b mt khc khng ܮc tit l ra hoc cha kim ra. Qua ljn "software" cng th, nhng "program" cng c th c "bug" phi hp vi h thng thit k "hardware" s b h ln h xung (crash). Nh vy, vic s sch ca h thng ngn hng cha th l thuc hn vo nhng b my micro mi ny. Nhng trong tng lai, s hon chnh nhng h thng micro s mang y nhng ha hn trong mi hot Ƕng hng ngy ca chng ta.

Bn cnh nhu cu ca kin trc gii tnh song song v dy chuyn cho h thng super micro computer, n cn ܮc ng dng vo nhng h thng tn k nh neuro-network, fuzzy logic, transputer... l nhng cu trc cho ngnh thng minh nhn to (artificial intelligent), cc bn s t hi liu h thng "super micro" c th t ܮc s thng minh nh loi ngܩi?

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