A1.1.7 · Computer fundamentals
A1.1.7 · 计算机基础
Secondary Memory Storage
二级存储器
Primary memory (A1.1.4) holds only what is in use right now and forgets it all when the power goes. Secondary storage is the opposite: slower to reach, but large and non-volatile, so it keeps files, programs and backups for the long term.
主存储器(A1.1.4)只保存当前正在使用的东西,而且一断电就全部忘记。二级存储器正好相反:访问起来更慢,但容量大且非易失,所以它长期保存文件、程序和备份。
A1's guiding question asks what principles underpin how a computer works. The principle here is a spread of trade-offs, speed, cost per gigabyte, durability, portability, so no one storage type is best for every job.
A1 的引导性问题问的是支撑计算机运行的原理。这里的原理是一组取舍的分布:速度、每 GB 的成本、耐用性、便携性,所以没有哪一种存储器对每一项工作都最好。
Explainer
讲解
Secondary storage, and internal vs external
二级存储器,以及内部与外部
Secondary storage is memory the CPU cannot use directly. Data has to be loaded from it into primary memory first. It is non-volatile (keeps its contents with no power), large, and slower than primary memory.
二级存储器是 CPU 不能直接使用的存储器。数据必须先从它加载到主存储器里。它是非易失的(断电也保留内容),容量大,而且比主存储器慢。
Internal drives are built inside the machine and hold the operating system, programs and the user's files. External drives connect from outside (usually by USB or over a network) and are used for backups, transferring files, and extra capacity.
内部驱动器装在机器内部,保存操作系统、程序和用户的文件。外部驱动器从外面连接(通常通过 USB 或经过网络),用于备份、传输文件和扩展容量。
Explainer
讲解
HDD vs SSD
HDD 与 SSD
These are the two main drive technologies, used both internally and externally. Almost every other choice below is a variation on one of them.
这是两种主要的驱动器技术,内部和外部都在用。下面几乎所有其他选择,都是这两者之一的变体。
| Compared on | HDD (hard disk drive) | SSD (solid state drive) |
|---|---|---|
| How it stores data | A spinning magnetic disk, read and written by a moving head | Flash memory chips, with no moving parts |
| Speed | Slower to read and write | Several times faster |
| Durability & noise | Moving parts, so more easily damaged by a knock, and it makes a slight noise | No moving parts, so it survives shocks and is silent |
| Power & heat | Uses more power, runs warmer | Uses less power, runs cooler |
| Cost | Cheaper per gigabyte, so good value for large amounts | More expensive per gigabyte |
| 比较项 | HDD(硬盘驱动器) | SSD(固态硬盘) |
|---|---|---|
| 如何存储数据 | 一张旋转的磁盘,由一个移动的磁头读写 | 闪存芯片,没有活动部件 |
| 速度 | 读写更慢 | 快好几倍 |
| 耐用性与噪音 | 有活动部件,所以更容易被磕碰损坏,而且会发出轻微的噪音 | 没有活动部件,所以能承受震动,而且静音 |
| 功耗与发热 | 耗电更多,运行时更热 | 耗电更少,运行时更凉 |
| 成本 | 每 GB 更便宜,所以大容量时性价比高 | 每 GB 更贵 |
SSD for anything where speed and toughness matter (the operating system, apps, a laptop, a portable backup you carry around). HDD where you need a lot of space cheaply and speed is not critical (media libraries, large archives).
凡是看重速度和耐用性的地方,用 SSD(操作系统、应用程序、笔记本电脑、随身携带的便携备份)。凡是需要便宜的大容量、而速度不关键的地方,用 HDD(媒体库、大型归档)。
Explore
探索
Seven storage devices
七种存储设备
Click each device to see what it is and the scenario it fits.
点击每个设备,看看它是什么、以及它适合的场景。
Check your understanding
检验你的理解
A budget smartphone ships with eMMC storage rather than a separate SSD. What is the most likely reason?
为什么入门级智能手机可能使用 eMMC 存储而不是 SSD?
Common mistake
常见错误
RecurringWhen a question describes a situation and asks which storage to use, a weak answer just names a device ("use an SSD") with no reason tied to the scenario. Connect the choice to what the scenario actually needs: because the drive will be carried around and dropped, choose an SSD because it has no moving parts to damage; because the user stores a huge video library and rarely opens old files, an HDD gives the most space for the money.
反复出现当题目描述一个情境并问该用哪种存储器时,薄弱的答案只是说出一个设备名("用 SSD"),却没有把理由和情境联系起来。要把选择和情境实际的需求挂钩:因为这个驱动器会被随身携带、可能被摔,所以选 SSD,因为它没有会损坏的活动部件;因为用户存了一个巨大的视频库、很少打开旧文件,HDD 用同样的钱能给出最多的空间。
Device only: "The photographer should use an SD card." True, but with no link to why (compact, shock and temperature resistant, fits the camera, expandable).
只有设备名: "这位摄影师应该用 SD 卡。" 没错,但没有说明为什么(小巧、抗震抗温、适配相机、可扩展)。
Choice plus reason: "An SD card, because it is compact enough to fit the camera's slot, resistant to shock and temperature for outdoor shoots, and the photographer can swap in a larger card or a fresh one when it fills up."
选择加理由: "SD 卡,因为它小到能插进相机的卡槽,在户外拍摄时抗震抗温,而且卡满时摄影师可以换一张更大的卡或一张新卡。"
Revision questions
复习题
Specimen-paper style. Write an answer, then reveal the marking points and mark yourself.
采用样卷风格。写下答案,然后展开评分要点给自己打分。
[4]Describe two ways an SSD and an HDD differ, covering both read/write speed and physical robustness.
[4]从性能和耐用性两方面,描述 HDD 与 SSD 的两点区别。
Marking points
评分要点
- Read/write speed: an SSD is several times faster than an HDD, because it uses flash memory chips while an HDD must wait for a magnetic disk to spin and a head to move to the right place.
- Physical robustness: an HDD has moving parts, so a knock can damage it and it makes a slight noise; an SSD has no moving parts, so it survives shocks and is silent.
- 读写速度:SSD 比 HDD 快好几倍,因为它使用闪存芯片,而 HDD 必须等磁盘旋转、磁头移到正确位置。
- 物理坚固性:HDD 有活动部件,所以磕碰会损坏它,而且会有轻微噪音;SSD 没有活动部件,所以能承受震动,而且静音。
[3]A user keeps a large video collection that they rarely watch and wants the cheapest way to store it safely. Recommend a storage type and justify your choice.
[3]某用户有一大批很少观看的视频收藏,想用最便宜的方式安全地存放它们。推荐一种存储类型并为你的选择说明理由。
Marking points
评分要点
- Recommend an HDD (or an external HDD).
- It is the cheapest storage per gigabyte, so it suits a large collection.
- The collection is rarely watched, so the slower read speed of an HDD does not matter here.
- It is non-volatile, so the videos are kept safely with no power.
- 推荐 HDD(或外置 HDD)。
- 它每 GB 最便宜,所以适合大型收藏。
- 这些视频很少观看,所以 HDD 较慢的读取速度在这里无关紧要。
- 它是非易失的,所以断电也能安全保存视频。
[3]Describe what network attached storage (NAS) is and one advantage it offers a household with several devices.
[3]描述什么是网络附加存储(NAS),以及它对一个拥有多台设备的家庭带来的一个好处。
Marking points
评分要点
- NAS is a storage device connected to the home network rather than to one computer.
- One advantage for a multi-device household (any one): every device can reach the same files without copying them around; all the devices can back up to one place; media can be streamed to any device on the network.
- NAS 是一个连接到家庭网络、而不是连接到某一台电脑的存储设备。
- 对多设备家庭的一个优点(任选其一):每台设备都能访问同一批文件,不必到处复制;所有设备都能备份到一个地方;媒体可以流式传输到网络上的任何设备。
[3]Compare a memory card and an optical disc in terms of durability and typical use.
[3]从耐用性和典型用途两方面,比较存储卡与光盘。
Marking points
评分要点
- Memory card: compact flash storage with no moving parts, so it is fairly robust to knocks; used inside cameras, phones and small devices where size matters.
- Optical disc: data as pits on a plastic disc, read by a laser; the surface can be scratched and it is more fragile; used for distributing films, music and software, and for archive copies.
- 存储卡:没有活动部件的紧凑闪存,所以对磕碰相当坚固;用在相机、手机和小型设备内部,那里尺寸很重要。
- 光盘:数据是塑料盘上的凹坑,由激光读取;表面会被划伤,而且更易碎;用于发行电影、音乐和软件,以及归档副本。
[2]State one reason a manufacturer would fit eMMC storage rather than an SSD in a budget laptop.
[2]说出制造商在预算型笔记本电脑中装 eMMC 存储而不是 SSD 的一个原因。
Marking points
评分要点
- eMMC storage is cheaper than an SSD.
- It lets the manufacturer keep the price of a budget laptop down, accepting that eMMC is slower and usually smaller than an SSD.
- eMMC 存储比 SSD 便宜。
- 它让厂商能把入门级笔记本的价格压低,代价是 eMMC 比 SSD 更慢、通常也更小。
Flashcards
记忆卡片
Active recall for this statement’s key terms.
针对本条考纲陈述关键术语的主动回忆练习。
Keep this statement’s practice with you
把这条考纲陈述的练习保存下来
Free account: unlock every revision question and flashcard for A1.1.7, and every other IB CS 2027 statement.
免费账户:解锁 A1.1.7 以及所有其他 IB CS 2027 考纲陈述的全部复习题和记忆卡片。