Computer Science - H046 考试技巧

计算器程序

常见错误

1. 1high涉及分数: 2Operating Systems

   Inability to clearly distinguish paging from segmentation.

   如何避免: Remember that paging divides memory into fixed-size physical blocks (partitions), whereas segmentation divides memory into logical, variable-sized blocks based on semantics/program structure.
2. 2high涉及分数: 9Ethical, moral and cultural issues

   Providing generic, superficial arguments in 9-mark essay questions without tying them to the scenario context.

   如何避免: Always apply the technical definitions directly to the given scenario (e.g., using terms like 'pupils', 'bandwidth', or 'school server' when discussing thin clients for a school system).
3. 3medium涉及分数: 2Algorithms

   Losing track of array boundary limits in loops (e.g. looping from 0 to length - 1 in bubble sort and getting a crash).

   如何避免: If accessing elements with 'index + 1' inside your loop, always ensure your loop terminates at length - 2 or check that the upper boundary does not cause an out-of-bounds error.
4. 4medium涉及分数: 3Programming techniques

   Confusing byVal and byRef parameter passing mechanisms, assuming byVal alters the original variable.

   如何避免: Recognize that byVal parameters receive a local copy of data, so changes remain local to the subroutine. Use byRef when you need the changes to persist and update the caller's argument.
5. 5medium涉及分数: 1Data Types

   Omitting intermediate calculations/workings in two's complement and sign/magnitude conversions.

   如何避免: Always write down the intermediate steps (such as listing place values, or showing the bitwise inversion step) to guarantee partial/method marks.
6. 6medium涉及分数: 2Databases

   In ER diagrams, incorrectly connecting entities directly (e.g. Customer to Product) when there is a many-to-many relationship.

   如何避免: Decompose many-to-many relationships by introducing an intermediary junction entity (like Order or OrderLine) with correct one-to-many crow's foot links.
7. 7low涉及分数: 2Web Technologies

   Writing syntax slips in client-side JavaScript password or field validation, such as using incorrect camelCase capitalization.

   如何避免: Always check exact case-sensitivity. Write camelCase correctly: document.getElementById("id") and label.innerHTML. Do not mix cases.
8. 8medium涉及分数: 6Structure and function of the processor

   Using illegal mnemonics or mixing memory address styles in Little Man Computer (LMC) assembly code.

   如何避免: Strictly stick to official OCR LMC instructions (ADD, SUB, STA, LDA, BRZ, BRP, BRA, INP, OUT, HLT, DAT) and always declare data labels at the bottom.
9. 9high涉及分数: 8Algorithms

   Failing to check 'fizz buzz' (modulo 3 AND 5) condition first in a fizz-buzz game loop.

   如何避免: In multi-condition branches, always evaluate the most restrictive combined condition (MOD 3 == 0 and MOD 5 == 0) first, before testing individual cases.