📚 Year 10 WJEC Computer Science: Unit Test Mock Exam Walkthrough | Year 10 WJEC 计算机：单元测试模拟卷解析
Mock exams are a vital checkpoint for Year 10 students studying WJEC Computer Science. This walkthrough breaks down a typical unit test paper, explaining the concepts and techniques needed to answer each question correctly. By reviewing common question types and model answers, you can boost your confidence and highlight areas for further revision.
模拟考试是Year 10学生学习WJEC计算机科学的重要检验。本文解析一份典型的单元测试卷，解释正确回答每道题所需的概念和技巧。通过复习常见题型和标准答案，你可以增强信心，并发现需要进一步复习的领域。
1. Binary and Hexadecimal Conversions | 二进制与十六进制转换
In binary, each bit represents a power of 2, starting from 2⁰ on the right. For the number 11010110₂, place the bits under the place values: 128, 64, 32, 16, 8, 4, 2, 1.
在二进制中，每位代表2的幂，从右边的2⁰开始。对于数字11010110₂，将各位放在位值：128、64、32、16、8、4、2、1下。
11010110₂ = 128 + 64 + 0 + 16 + 0 + 4 + 2 + 0 = 214₁₀
ary, convert each hex digit separately: 5₁₆ = 0101₂, F₁₆ = 1111₂. Thus, 5F₁₆ = 0101 1111₂.
十六进制使用基数为16，数字为0-9及A-F（A=10, B=11, ..., F=15）。将5F₁₆转换为二进制，分别转换每个十六进制位：5₁₆ = 0101₂，F₁₆ = 1111₂。因此5F₁₆ = 0101 1111₂。
Always show your working in the exam – you may earn marks even if the final answer is slightly wrong. For denary to binary, repeatedly divide by 2 and record the remainders.
考试中务必展示解题过程——即使最终答案略有错误，也可能获得步骤分。将十进制转二进制，反复除以2并记录余数。
2. Logic Gates and Truth Tables | 逻辑门与真值表
AND B) OR (NOT C), list all combinations of inputs A, B, C (0 or 1). Then evaluate the combined expression step by step: first compute A AND B, then NOT C, and finally OR the results.
要构造Q = (A AND B) OR (NOT C)的真值表，列出输入A、B、C的所有组合（0或1）。然后逐步求值：先计算A AND B，再计算NOT C，最后将结果进行OR运算。
| A | B | C | A AND B | NOT C | Q |
|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 1 | 1 |
| 0 | 0 | 1 | 0 | 0 | 0 |
| 0 | 1 | 0 | 0 | 1 | 1 |
| 0 | 1 | 1 | 0 | 0 | 0 |
| 1 | 0 | 0 | 0 | 1 | 1 |
| 1 | 0 | 1 | 0 | 0 | 0 |
| 1 | 1 | 0 | 1 | 1 | 1 |
| 1 | 1 | 1 | 1 | 0 | 1 |
Notice how the OR operation yields 1 if at least one input is 1. Common exam questions ask you to draw the logic circuit or complete the truth table. Always double-check NOT gates.
注意OR运算在至少一个输入为1时结果为1。常见考题要求画出逻辑电路或补全真值表。务必仔细检查非门。
3. Computer Hardware Components | 计算机硬件组件
The Central Processing Unit (CPU) executes instructions and processes data. It consists of the Control Unit (CU) that directs operations and the Arithmetic Logic Unit (ALU) that performs calculations and logical comparisons.
中央处理器（CPU）执行指令并处理数据。它由控制单元（CU）和算术逻辑单元（ALU）组成，前者指挥操作，后者执行计算和逻辑比较。
RAM (Random Access Memory) holds data and instructions currently in use by the CPU. It is volatile – data is lost when power is off. Secondary storage (e.g., HDD, SSD) provides permanent storage for files and software. ROM (Read Only Memory) is non-volatile and stores the BIOS to boot the computer.
随机存取存储器（RAM）保存CPU当前使用的数据和指令，属于易失性存储器——断电数据丢失。辅助存储器（如HDD、SSD）为文件和软件提供永久存储。只读存储器（ROM）是非易失性的，存放用于启动计算机的BIOS。
In a unit test, you might be asked to identify components that affect performance, such as clock speed, number of cores, and cache size.
单元测试中，可能会问影响性能的组件，例如时钟频率、核心数和缓存容量。
4. The Fetch-Decode-Execute Cycle | 取指-解码-执行周期
The CPU continuously repeats the fetch-decode-execute cycle to process instructions. Fetch: the address in the Program Counter (PC) is copied to the Memory Address Register (MAR). The instruction is fetched from RAM into the Memory Data Register (MDR) and
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