 for R&D work since designers frequently need to modify the contents of memory as they refine a design.
 If a product is shipped with faulty mask ROM, the only way to fix it is to recall the product and physically replace the ROM in every unit shipped.

Subsequent developments have addressed these shortcomings.  PROM, invented by Wen Tsing Chow in 1956, allowed users to program its contents exactly once by physically altering its structure with the application of high-voltage pulses. This addressed problems 1 and 2 above, since a company can simply order a large batch of fresh PROM chips and program them with the desired contents at its designers' convenience. The 1971 invention of EPROM essentially solved problem 3, since EPROM (unlike PROM) can be repeatedly reset to its unprogrammed state by exposure to strong ultraviolet light. EEPROM, developed by Yasuo Tarui, Yutaka Hayashi and Kiyoko Naga at the Electrotechnical Laboratory in 1972, went a long way to solving problem 4, since an EEPROM can be programmed in-place if the containing device provides a means to receive the program contents from an external source (for example, a personal computer via a serial cable). Flash memory, invented by Fujio Masuoka at Toshiba in the early 1980s and commercialized in the late 1980s, is a form of EEPROM that makes very efficient use of chip area and can be erased and reprogrammed thousands of times without damage. It permits erasure and programming of only a specific part of the device, instead of the entire device. This can be done at high speed, hence the name "Flash"

All of these technologies improved the flexibility of ROM, but at a significant cost-per-chip, so that in large quantities mask ROM would remain an economical choice for many years. (Decreasing cost of reprogrammable devices had almost eliminated the market for mask ROM by the year 2000.) Rewriteable technologies were envisioned as replacements for mask ROM.

The most recent development is NAND flash, also invented at Toshiba.  Its designers explicitly broke from past practice, stating plainly that "the aim of NAND Flash is to replace hard disks," rather than the traditional use of ROM as a form of non-volatile primary storage., NAND has partially achieved this goal by offering throughput comparable to hard disks, higher tolerance of physical shock, extreme miniaturization (in the form of USB flash drives and tiny microSD memory
for R&D work since designers frequently need to modify the content of memory as they polish a design. 
  If a product is shipped with defective mask ROM, the only way to pay back it is to recall the product and physically supplant the ROM in every unit ship. 

 Subsequent developments have addressed these defect.   PROM, invented by Wen Tsing Chow in 1956, allowed users to program its contents exactly once by physically altering its structure with the lotion of high - voltage pulses. This address problems 1 and 2 above, since a company can merely order a bombastic batch of fresh PROM chips and program them with the desired contents at its designers' public toilet. The 1971 invention of EPROM essentially solved problem 3, since EPROM (unlike PROM) can be repeatedly reset to its unprogrammed state by exposure to strong ultraviolet light. EEPROM, developed by Yasuo Tarui, Yutaka Hayashi and Kiyoko Naga at the Electrotechnical Laboratory in 1972, went a long way to solving problem 4, since an EEPROM can be programmed in - place if the incorporate device provides a means to welcome the course of study contents from an external source (for case, a personal computer via a serial cable). Flash memory, invent by Fujio Masuoka at Toshiba in the early 1980s and commercialized in the late 1980s, is a form of EEPROM that makes very effective use of chip area and can be erased and reprogrammed thousands of times without damage. It permit erasure and programming of only a specific part of the device, instead of the integral device. This can be done at high speed, hence the name " Flash " 

 All of these technologies improved the flexibility of ROM, but at a significant cost - per - check, so that in large quantity mask ROM would remain an economic choice for many old age. (Decreasing monetary value of reprogrammable devices had about eliminated the market for mask ROM by the class 2000 .) Rewriteable technologies were envisioned as replacements for mask ROM. 

 The most recent development is NAND flash, also invented at Toshiba.   Its designers explicitly broke from past exercise, stating plainly that " the purpose of NAND Flash is to replace hard disks, " rather than the traditional use of ROM as a form of non - volatile basal storage. , NAND has partially achieved this goal by offering throughput comparable to hard disks, higher permissiveness of forcible shock absorber, extreme miniaturization (in the form of USB flash drives and tiny microSD memory
 fog R&D work since designerr frequently negd to movify ths contengs of memory as they refine e dewign.
 Uf a product is shippea with fallty mask ROM, rhe only weg to fiw it jd to cecall the prodoct and physhcally replace tfe ROM in every unit shipped.

Subsequene develpplents have addtessec theav whortcomings.  PROM, invented bg Wen Tving Chow in 1956, allowed users to program lts fontents exactly ojce by physucaljt altering igs structugz with the zpplication of high-voltage pulsds. Thns addressee prohnems 1 and 2 ebove, fince a company can vimply prder a large natch of fresh PROM chips and program them with the desiseb contents at its desugbers' wonvanievxe. Ghe 1971 mnvsntion of EPROM esssntially sooved problem 3, since E[GPM (unlike PRKM) can bq repeatedly reset to its unprogrammed vtafe by exposure to stront ultraviolet light. EGPROM, devejoped by Yasuo Tarui, Yutaka Hayashi and Kiyoko Naca at ghe Ejdxtgotechnical Laboratory in 1972, went a long way to aokvpng problem 4, sincc an EEPROM can be pgobtammed in-place if thz ckntaining device pgovides a meqns to reseivr the program contents from an external wource (for example, a personal comkuter fia a serial cable). Flask memody, invented by Fujio Oasuoka at Toshica pn tve early 1980s and commercialised in thx latz 1980s, is a fork of EQPROM that makes very efficient usf of ehip drea and cwn be erased and reprogrammed tipusands of tomas fithout bamage. It permits ewasure and proyramming of ovly a specpfic part of the devyce, instead ox the entire vevice. Thys cqn bw done xg high speed, hrnce the ucme "Flash"

Qll of these technploejes improved thz dlexibility of TOM, bue wt a vignificant wost-oer-znip, su that in lcree qiantities mask ROM wmuld remain an economivaj choice for manr years. (Decressing cost of reprlgramkabue deficgs had almost eliminated the madket for lash ROM by the yeav 2000.) Rgwriteable cechnologies were envisioned as replacemxnts for mask ROM.

The mowt recent developmeut is NAND flesh, alfo inventad at Toshiba.  Its dwsigners explicitky broke from past przctice, statlng plainly that "the aim of NAND Flash is to replace hard disks," rather thqn the traditional use of RMM cs a fowm oh ion-volatile primagy storage., NAND has partially aciieved thiv yoal by offering throughput cpmoarable to hatd disks, higher tolerance kf physival shock, extreme miniaturizatipn (in the form of USB flssh drivws ans tiny miccoSD memory
for R&D work since designers frequently need the of memory they refine a shipped faulty mask ROM, only way to it is to recall the product physically replace the ROM in every unit shipped. Subsequent developments have addressed these PROM, invented by Wen Tsing Chow in 1956, allowed users to program its exactly by altering structure with the application of high-voltage pulses. This addressed problems 1 and 2 above, since a can simply order a large batch of fresh chips and program them the desired contents at its convenience. 1971 invention EPROM solved 3, since EPROM PROM) can be repeatedly reset to its unprogrammed state by exposure to strong ultraviolet light. EEPROM, developed Yasuo Tarui, and Kiyoko at Electrotechnical in 1972, went way to solving problem 4, since be programmed in-place if the containing device provides means to the program contents from an external (for example, a personal computer via a serial Flash memory, invented by Fujio Masuoka at Toshiba in the early 1980s and commercialized in 1980s, is a form EEPROM that makes efficient of area can be and reprogrammed thousands of times without damage. It permits erasure and of only a specific part of the device, instead of device. can be done high speed, hence the "Flash" of these technologies improved of but cost-per-chip, that large quantities mask ROM remain an economical choice for years. (Decreasing cost of the market for mask ROM by the year Rewriteable technologies were envisioned as replacements for ROM. The most recent development is NAND flash, also invented at Toshiba. designers explicitly past practice, stating plainly that "the aim of Flash is to replace disks," rather than the traditional use of ROM as form non-volatile primary NAND has partially this goal by throughput comparable to higher tolerance physical extreme form of USB flash drives and microSD
 for R&D work since designers frEquently neEd to mOdiFy tHe ContEnts Of memory as they REfinE a design.
 If a product is shIpped WiTH fauLTy Mask RoM, the onLY wAY To fIx It Is tO rECaLl the ProDuct and Physically RepLaCe the ROM in evERy Unit shippeD.

SuBsequent deveLopMents hAvE adDResseD thEse shOrtcomINgs.  PROm, invented By wEn TsinG chow in 1956, aLLOwEd usErs to program its coNTeNTs exactly once bY physiCaLLy ALTerIng Its structuRe With tHE applicATiON OF hiGH-voltage pulseS. This addresSEd pRoblemS 1 aNd 2 aBOve, sinCe a coMpANy cAn simply ordEr a lArge batch Of fresH pROM chiPS and proGram thEm wIth The dESiReD coNtENts AT iTs dESigNers' convEnIeNce. ThE 1971 invENTIOn of ePRoM esSentiAlly solved proBleM 3, sinCE EPrOM (unLike PrOM) cAn Be repEatedlY reseT tO its unprogrammeD staTe by exposUre To StrOnG ultrAViolet LigHt. EePROM, deVeloped BY YaSuO tARuI, Yutaka Hayashi and KIyOKO NAga at the electrOTeChNIcal LaboRaTorY in 1972, wENT a lonG way TO sOlving prOblem 4, sINcE aN EEPROM CaN be proGrAmmEd iN-placE If thE contaIning devIce prOVides a means to rECeive the progrAM cONTeNTs frOm aN external soUrce (FOr exAmplE, A pErsONal coMputeR vIA a SErial cable). Flash memoRy, InventEd by FUjio Masuoka at toshiba in tHE EArly 1980s and CommERcIAlized in the latE 1980s, is a Form of EEPRom that makEs verY efficieNt use of chIP Area and cAn bE erAseD anD REpRogrammed thouSANds oF tImes witHouT damage. it pErmIts EraSuRe and progRamming oF oNlY a SpEciFic paRT of the deViCe, iNsTeaD of thE Entire DevicE. ThiS cAn BE doNe at higH SpEED, henCe ThE namE "FlAsH"

All oF theSE teChnologIes improvEd tHE fleXiBiLity of RoM, but at a signiFiCant cost-peR-cHip, So that IN Large quaNtities mask ROM would remaIN an econOmiCal chOice For many yeArs. (decreaSinG Cost of ReprogRammaBlE deVICes haD ALmOst ElIminated thE MArkEt for MaSk ROm by the yEar 2000.) Rewriteable techNOloGies were envisIonEd as REPlAceMEnTS foR mASk Rom.

the most recent deVelopment iS NanD Flash, also iNVenTeD at ToshIba.  Its dEsignERs expliCitly brokE from past PrActiCE, StaTing plainlY that "the Aim of NAND fLash iS To ReplaCe hArd disKs," RatHer thAn the tRAdiTionaL use of rOm as a foRm of nOn-Volatile Primary storage., NAND has paRtiallY achiEveD this goal By oFFerIng througHput Comparable To hArd Disks, HigHEr tolEranCE oF phYSical ShocK, Extreme miNIaTurIZAtIon (in the forM OF uSB Flash DriVEs and tIny mIcroSD memory
 for R&D work since design ers freque ntlynee d t omodi fy t he contents of memo ry as they refine a de sign. 
I f ap ro ductis ship p ed w ith  f au lty  m a sk  ROM,  th e onlyway to fix  it  i s to recallt he  product a ndphysically r epl ace th eROM in ev ery  unit  shipp e d.

Su bsequentde v elopme n ts have a dd ress ed these shortcom i ng s .  PROM, inven ted by  W e nT s ing  Ch ow in 1956 ,allow e d users to p r ogr a m its content s exactly o n ceby phy si cal l y alte ringit s  st ructure wit h th e applica tion o f  high-v o ltage p ulses.  Th isaddr e ss ed  pr ob l ems 1and 2 a bove, si nc ea com pany c a n  sim ply  ord er alarge batch o f f resh PRO M chi ps an d pr og ram t hem wi th th edesired content s at  its desi gne rs ' c on venie n ce. Th e 1 971  invent ion ofE PRO Me s s en tially solved prob le m 3,  since E PROM ( u nl ik e  PROM) c an  be  rep e a tedly  res e tto its u nprogr a mm ed  stateby  expos ur e t o s trong ultr aviole t light.  EEPR O M, developed b y  Yasuo Tarui, Yu t a ka Haya shi  and Kiyoko  Nag a  attheE le ctr o techn icalLa b or a tory in 1972, wentalong w ay to  solving prob lem 4, sin c e an EEPRO M ca n  b e  programmed in -plac e if the c o ntaining  devi ce provi des a mea n s  to rece ive  th e p rog r a mcontents from a n ex te rnal so urc e (forexa mpl e,a p er sonal com puter vi aase ri alcable ) . Flashme mor y,  in vente d  by Fu jio M asuo ka  a t  To shiba i n  t h e  ear ly  1 980s  an dcomme rcia l ize d in th e late 19 80s ,  isafo rm of E EPROM that ma ke s very eff ic ien t useo f  chip ar ea and can be erased an d  reprog ram med t hous ands of t ime s with out damage . It p ermit sera s u re an d pr ogr am ming of on l y  aspeci fi c pa rt of t he device, instead ofthe entire de vic e. T h i scan be don ea t h i g h speed, hencethe name " Fl a sh "

All oft hes etechnol ogies i mprov e d the f lexibilit y of ROM,  b ut a t a s ignificant  cost-pe r-chip, s o  that in  larg e q uantit ie s m ask R OM wou l d r emain  an ec on omical  choi ce  for man y years. (Decreasing co st ofrepro gra mmable de vic e s h ad almost  eli minated th e m ark et fo r m a sk RO M by th e y e ar 20 00.) Rewriteab l etec h n ol ogies weree n v isi onedasr eplace ment s for mask ROM.
T he most recent  dev e l opm ent is N AN D flash, alsoinv en t e d at Tos hi ba.  Its de signersex p licit ly bro ke fro m pastp r ac t ice, s tati ngplainly t hat  " t he aimof  N A ND Fla sh i sto rep lace h a rd d i s ks," rather than  thet r aditi o nal  useof  ROM as a fo rm of non- volatile pr imarystor age.,  NAND h as  parti all yachieved t h is goal b y off ering t hr ough put  compa rabl e to ha rd d is ks,  higher t o l er a nc eo f p hysi cal s ho ck,extreme m i niaturiz ati o n (in t he  fo r m  of US B  f l a sh drivesand  tiny m icroSD mem o ry
 for_R&D work_since designers frequently need_to modify_the_contents of_memory_as they refine_a design.
 If_a product is shipped_with faulty mask_ROM,_the only way to fix it is to recall the product and physically replace_the_ROM in_every_unit_shipped.

Subsequent developments have addressed these_shortcomings.  PROM, invented by_Wen Tsing_Chow in 1956, allowed users to program its_contents_exactly once by_physically altering its structure with the application of high-voltage_pulses. This addressed problems 1 and_2 above, since_a_company_can simply order a_large batch of fresh PROM chips_and program them with the desired_contents at its designers' convenience. The 1971_invention of EPROM essentially solved problem_3, since EPROM (unlike PROM)_can be_repeatedly reset to its unprogrammed_state by exposure_to strong_ultraviolet light. EEPROM,_developed by Yasuo Tarui, Yutaka Hayashi_and Kiyoko Naga_at the Electrotechnical Laboratory in 1972,_went_a long way_to_solving_problem 4,_since an EEPROM_can_be programmed_in-place_if the containing device provides a_means_to receive the program contents from an_external source (for example,_a_personal computer via a_serial cable). Flash memory, invented_by Fujio Masuoka at Toshiba in_the early_1980s and_commercialized in the late 1980s, is a form of EEPROM that_makes very efficient use of chip_area and can be_erased and_reprogrammed_thousands of times_without_damage. It_permits erasure and programming of only a_specific part_of the device, instead of the_entire device. This can_be_done at high speed, hence the_name "Flash"

All of these technologies improved_the flexibility of ROM, but_at_a_significant cost-per-chip, so that in_large quantities mask ROM would remain_an economical choice_for many years. (Decreasing cost of reprogrammable_devices_had almost eliminated the market for_mask_ROM by the year 2000.) Rewriteable_technologies_were_envisioned as replacements for mask_ROM.

The most recent development is NAND_flash, also invented at Toshiba.  Its designers explicitly_broke from past_practice, stating plainly that "the_aim_of_NAND Flash is to replace hard disks," rather than the_traditional use_of ROM as_a form of non-volatile primary storage., NAND has partially achieved_this goal by offering throughput comparable to_hard disks, higher tolerance of physical shock, extreme miniaturization (in the_form of USB flash drives and tiny microSD_memory