计算机对主存的要求是速度快、容量大、价格低，但现实情况三者很难统一于一身，很难找到这种存储器件。为了能解决这一需求，在主存与CPU之间增加一级　cache，其主要目的是为解决(1)，每次CPU访问主存时，都先要查询该单元数据是否已调入cache。为了把主存地址变成cache地址，常常使用3种cache地址映像方式，其时全相联地址映像方式，使用起来最方便、最灵活但查找很困难，为了达到cache的要求，实现时常常采用(2)，按照cache字块标志的内容访问映像存储器，查找命中的cache字块地址。

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Soon,　more　of　the　information　we　receive　via　the　Internet　could　come(71)in　digital　wrappers.

Wrappers　are　made　up(72)software　code　that's　targeted　to　do　specific　things　with　the　data(73)within　them,　such　as　helping　to　define　queries　for　search　engines.　They　also　keep(74)from(75)access　to　that　code.

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Developing　reliable　software　on　time　and　within(66)represents　a　difficult　endeavor　for　many　organizations.

Usually　business　solutions　have　three　main　aspects:　people,(67),and　technology.　The　main　reason　for　failing　software　projects　has　little　to　do　with　technology　and　tools,　and　much　to　do　with　lack　of　process(68).　Experience　has　shown　that　introducing　new　technology　and　tools　in　an　immature　or　undisciplined　environment　is　likely　to　increase　the　chaos.　CASE　tools　are　not　enough.　"A　fool　with　a　tool　is　still　a　fool　!"

Structured　method　was　the　first　wave　of　the　software　industry.　This　was　the　beginning　of　transforming　software　development　from　a"(69)industry"　to　mass　production.　Software　process　movement　if　the　second　wave　in　the　software　industry.　The　process　maturity　movement　prepares　the　way　for　the　third　wave　of　the　software　industry　:"software　industrialization".　Software　development　will　become　like　an　assembly　and　manufacturing　process.　A　cfiticalenabling　factor　is　adisciplined　software　engineering　.　process　with　predictable　quality,(70)and　functionality.

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