英特尔Thunderbolt技术十大问答

英特尔(Intel)日前宣布推出全新高速个人计算机传输技术——Thunderbolt(先前代号为Light Peak)，号称通过一条传输线就能执行高速数据传输并传送HD影像，其速度达10Gbps，30秒内便能传送一部HD电影。该项英特尔研发的技术并与苹果计算机(Apple)进行技术合作，率先于苹果计算机全新的MacBook Pro笔记本电脑系列中采用。

根据英特尔新闻稿的说明，Thunderbolt技术采用两种通讯方式(或通讯协议)，包括用在数据传输的PCI Express，以及用在显示的DisplayPort。PCI Express具备充裕的弹性，能链接几乎任何装置，DisplayPort则能驱动超过1080p分辨率的屏幕，并同时支持8个声道的音效。Thunderbolt技术与目前的DisplayPort屏幕和接头兼容。所有Thunderbolt技术装置都共享一个接头，使用者可利用电线(electrical)或光纤(optical cable)轻易串接其装置。

Thunderbolt技术的设计是为了满足HD媒体创作者的需求。例如，摄影从业人员可运用高带宽音效与视讯撷取/混合装置，并以低延迟与高精准的时间同步设备来进行实时的处理后制，释放自己的创意。在10Gbps的超高传输速度下，超大容量的媒体档案能更快传输完毕，减少观看与编辑影片的等待时间，使用者能够更快备份与回存数据，内容建文件时的等待时间也更为缩短。

英特尔指出，对于行动式个人计算机用户而言，它意谓仅须用超轻薄笔记本电脑上的一个接头，就能连结至家中或办公室的高速媒体与HD显示功能。Thunderbolt技术能补足其他英特尔仍持续支持的I/O技术不足之处。

但光看以上的新闻稿内容，各位读者对这个新冒出头的、性能超越Firewire(IEEE1394)与USB 3.0的高阶接口技术Thunderbolt应该还是有不少疑问；以下是EETimes美国版编辑所整理出的十大问答集，希望有助于大家更认识这个新技术。

1. Thunderbolt的完整技术规格何时会公开？

到目前为止，英特尔仅对Thunderbolt产品开发伙伴(名单不公开)提供该技术规格详情，并打算在7月以前释出一套开发工具，包含Thunderbolt技术规格在内；但该公司并没有计划在网络上公布技术细节。

2. Thunderbolt是什么东东？

Thunderbolt是一个英特尔开发的新互连接口，苹果最新推出的MacBook Pro系列笔记本电脑将会是第一批采用该接口的产品；该技术能在一个共享的传输埠上支持10Gbps的双向通道，以达到40Gbps的最大总吞吐量；PCI Express与DisplayPort支持该传输埠的最上层。

点击进入第二页：Thunderbolt会取代USB吗？

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3. Thunderbolt适合那些应用？

根据英特尔的介绍，Thunderbolt能实现更具弹性的系统设计；例如笔记本电脑或精简型计算机，能通过该接口与高阶装置、显示器或外接设备连结，不需要将所有的功能都集中在同一个机箱里。也就是说，基本上该接口是一个在主机外部的PCI Express端口，能用来让PC与PC之间，或是数字摄影机、各种装置互传大型档案，也能当作DisplayPort接口链接显示器。

4. Thunderbolt会取代USB吗？

不会；英特尔会持续支持USB，也会在未来的PC芯片组整合新一代USB 3.0技术；英特尔将Thunderbolt视为USB的互补技术，两者是着重在不同的应用领域。不过英特尔也承认Thunderbolt与USB 3.0会有一些重迭的应用，特别是在储存领域。

目前已经有数家芯片业者针对外接式储存数组设备，推出了支持USB 3.0转接SATA接口的产品；对此英特尔的Thunderbolt计划暨营销总监Jason Ziller仅表示：“我们预期Thunderbolt与USB 3.0的并存，会为消费者提供个多样化的产品价格/性能选项。”

5. 谁会提供Thunderbolt芯片？

在短期看来只有英特尔一家厂商；目前该公司可供应一款Thunderbolt控制器芯片，而且并未决定何时将开放该技术规格给其他业者生产类似芯片。目前英特尔Thunderbolt控制器的技术细节也未公开，无论是价格、芯片尺寸、功耗，或是该芯片是否需要独立主机与外围控制器的设计，通通都是未知数。

6. Thunderbolt会支持光纤电缆吗？

根据英特尔的新闻稿，意思应该是“会”；但目前该技术仅提供采用铜缆、以及3公尺的最长传输距离；英特尔表示目前仍在进行光纤版Thunderbolt的研发工作，但实际问世恐怕还需要几年的时间。而目前Thunderbolt所使用的铜缆技术细节，也是未公开的机密。

点击进入第三页：谁会支持Thunderbolt技术？

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7. Thunderbolt本来不是就打算支持光纤电缆？

是这样没错；在2009年9月英特尔发表　Light Peak技术时(参考：挑战USB 3.0　Intel发布10Gb/s级Light Peak技术)，将之形容为“系统间的光学链接”，但后来在研发策略上似乎有所改变。

根据英特尔Thunderbolt工程总监Aviel Yogev的说法：“厂商伙伴告诉我们，在光学技术成本能大幅下降之前，其采用会有其困难度；我们会在某一天需要转向光学，但在接下来几年该技术仍会是采用电线(铜缆)。”Yogev强调，英特尔并未放弃开发光学链接：“光学是我们的未来目标，总有一天也会是需要它，所以我们目前仍在进行相关研发，评估最佳推出时机。”

8. Thunderbolt技术蓝图？

目前尚不清楚；英特尔曾透露该公司将在2013年支持每秒兆兆位(terabit)等级的传输，可能采用的方法一是增加10 Gbps线路的数量，二是提升单一线路的速率。英特尔也说过，该公司总有一天会支持能大幅增加带宽、并将传输距离拉长到数十公尺的光缆。

9. 谁会支持Thunderbolt技术？

苹果已经抢先成为在主机系统采用Thunderbolt的第一家厂商，但目前还不知道会不会有其他系统厂跟进；已经宣布将支持Thunderbolt的外围设备厂商则包括Aja、Apogee、Avid、Blackmagic、LaCie、Promise与Western Digital(WD)，其中只有两家厂商有实际展示相关产品，但价格、出货日期等细节也未定。(请参考：Inside Thunderbolt: Videos, photos, details)

至于半导体供货商则没有半家出现在Thunderbolt应援团名单中，缺席的还有硬盘机大厂希捷(Seagate)、日立(Hitachi GST)、东芝(Toshiba)与其他PC制造商。

10. Thunderbolt是否能避免重蹈Firewire覆辙？

几年前，Firewire俨然已成为高阶计算机与消费性电子产品专属的接口技术，获得了从芯片业者到系统厂商的广泛支持，其数据吞吐量与低延迟性能远胜于USB。当时苹果也是首先在系统产品采用Firewire的厂商，并积极拉拢出版与媒体界的用户。

但Firewire阵营所订定的技术蓝图却稍嫌冗长而混乱，让部分厂商不知道该马上支持该技术，还是要等下一代版本；在此同时，USB则是采取稳健步伐持续赢得设计案，并在速度上逐步缩小与Firewire之间的差距。现在最新的USB 3.0性能已经超越Firewire了，市场对后者的支持热度不再；后起之秀Thunderbolt该如何避免步上Firewire后尘？是个大问题。

翻译：Judith Cheng

点击进入参考原文：Ten things to know about Intel's Thunderbolt

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Ten things to know about Intel's Thunderbolt

Rick Merritt

Intel and Apple sent quite a shock wave through the PC and consumer electronics communities today with the launch of Thunderbolt, a high-end interconnect that leapfrogs both Firewire and USB 3.0.

Plenty of questions remain unanswered. But Intel has shed light on some of the major issues. Here's the EE Times FAQ on Thunderbolt.

1. When will a full spec be openly available?

Intel is so far only sharing full technical specs of Thunderbolt under non-disclosure with partners making Thunderbolt products. It plans to release a developer's kit before July that will include technical specifications for Thunderbolt. However, it currently has no plans to publish details of the spec online.

2. What is Thunderbolt?

Thunderbolt is new interconnect from Intel first available on new Apple MacBook Pro notebooks. It supports two 10 Gbits/s bi-directional channels on a common transport for 40 Gbits's max aggregate throughput. PCI Express and DisplayPort protocols are supported on top of that transport.

3. What are the applications for Thunderbolt?

Intel defines several of them.

Thunderbolt can be used to create flexible system designs. For instance, thin notebooks or clients can use Thunderbolt to link to high-end drives, displays and other external devices instead of building them all into one box. Essentially, it provides a PCI Express link outside the box.

The interface will be used to quickly send big files between PCs, cameras and drives. It will also be used with DisplayPort as a link to displays.

4. Will Thunderbolt kill USB?

No, Intel will continue to support USB and will integrate the next-generation USB 3.0 technology in its future PC chip sets. Intel sees Thunderbolt and USB as complementary, generally addressing different applications.

However, Intel does admit USB 3.0 and Thunderbolt will overlap in some applications, particularly in storage. Several chip makers have introduced products supporting USB 3.0 to SATA for external storage arrays.

"We expect [use of both USB 3.0 and Thunderbolt] will enable various price/performance models and choices for consumers," said Jason Ziller, director of Thunderbolt planning and marketing at Intel.

If Thunderbolt takes off it could blunt the growth trajectory for USB. But USB is used so broadly it will continue to be supported and grow for a very, very long time.

5. Who will supply silicon for Thunderbolt?

Only Intel for the foreseeable future.

Intel is supplying a Thunderbolt controller and is not commenting on whether it will open up the spec for others to make similar chips. Details of the controller are currently not available, leaving open questions about its price, size, power consumption and whether separate host and peripheral controller designs are required.

6. Will Thunderbolt support optical cables?

Currently it is only available for copper cables supporting distances up to three meters. Intel said it is still doing R&D work on an optical version which will be made available eventually, but that could be a few years away.

Like Thunderbolt itself, the full details are not available for the unique copper cable it uses.

7. Wasn't Thunderbolt supposed to support optical cables?

Yes, initially Intel announced the technology in September 2009 under the name Light Peak as an optical system-to-system link. However, that changed according to Aviel Yogev, director of Thunderbolt engineering at Intel.

"OEMs told us that until vendors can reduce the cost of optics significantly they have difficulties adopting that technology," Yogev said. "At some point we need to move to optical, but for the next few years it will be electrical [i.e. on copper cables]," he said.

"We haven't abandoned an optical connection," he added. "Optics is in our future and will be needed over time, so we are still doing R&D in that area and assessing when the time is right," he said.

8. What's the roadmap for Thunderbolt?

This too is unclear. Intel suggested it will support terabit/second throughput by 2013. It could do that by increasing the number of 10 Gbit/s lanes or increasing lane speed. Intel said it will eventually support optical cables which could bolster bandwidth and support distances of tens of meters.

9. Who is supporting Thunderbolt?

Apple struck a deal from Intel to be the first OEM to use it in a host system, the new MacBook Pro notebooks. It is not clear which OEMs, if any, will support the interface.

Several peripheral makers said they will support Thunderbolt. They include Aja, Apogee, Avid, Blackmagic, LaCie, Promise and Western Digital. So far only two of those companies are demonstrating working products and none have released details about what products they will ship, when and at what prices.

Missing from this list are any semiconductor vendors, top drive makers such as Seagate, Hitachi GST and Toshiba and any other PC makers.

10. How will Thunderbolt avoid the problems of Firewire?

This is perhaps the biggest unanswered question. Years ago, Firewire appeared to be a shoe-in as the high-end computer and consumer interface. It had broad backing from chip and systems companies and was way ahead of USB is throughput and latency.

Ironically, Apple was one of the companies that took the lead building Firewire into its systems, courting its users in publishing and media creation.

But Firewire proponents rolled out a somewhat long and confusing roadmap, leaving some to question whether they wanted to support the interface right away or wait for a future generation. Meanwhile, USB made steady progress getting design wins and regularly updating its speeds, closing the gap with Firewire.

USB 3.0 was poised to leapfrog Firewire which has lost broad backing until Thunderbolt struck.