Title MOCK AS - P1 Variant D (Sir Aaqib).pdf ✅

1 hour 30 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use an HB pencil for any diagrams, graphs or rough working. ● Calculators must not be used in this paper. INFORMATION ● The total mark for this paper is 75. ● The number of marks for each question or part question is shown in brackets [ ]. ● No marks will be awarded for using brand names of software packages or hardware. COMPUTER SCIENCE _____________________________________________________________________________________ ______________________________________________________________________________________ PAGE | 1 Compiled by Sir Aaqib Khan - AKI By: SIR AAQIB KHAN - Aki This document has 14 pages. Any blank pages are indicated. AS - Level - Computer Science CAIE Practice Paper Variant C By: Aaqib Khan - AKI Paper 1 Theory Fundamentals CAIE Practice Paper - 2024 CAIE PRACTICE PAPER SESSION - 24 AS - Level PAPER - 1 VARIANT D COMPUTER SCIENCE Variant - D 9618/12
1 (a) Each of the following bytes represents an integer in two’s complement form. State the denary value. (i) 0111 0111 Denary .................................................. [1] (ii) 1000 1000 Denary .................................................. [1] (iii) Express the following integer in two’s complement form. -17 [1] (iv) State in denary, the range of integer values that it is possible to represent in two’s complement integers using a single byte. Lowest value .................................................. Highest value .................................................. [1] (b) (i) Convert the following denary integer into Binary Coded Decimal (BCD). 653 .......................................................................................................................................[1] (ii) A 3-digit BCD representation has been incorrectly copied. It is shown as: 0 1 0 0 1 1 1 0 0 0 1 0 State how you can recognise that this is not a valid BCD representation. ........................................................................................................................................... .......................................................................................................................................[1] (iii) Describe a practical application where BCD is used. ........................................................................................................................................... .......................................................................................................................................[1]
(PC). General purpose registers A B C Arithmetic Logic Unit (ALU) E F D Some components and buses only have labels A to F to identify them. For each label, choose the appropriate title from the following list. The title for label D is already given. • Control bus • System clock • Data bus • Control unit • Main memory • Secondary storage A ........................................................................................................................................... B ........................................................................................................................................... C ........................................................................................................................................... D Address bus E ........................................................................................................................................... F ........................................................................................................................................... [4] 2 (a) The diagram shows the components and buses found inside a typical Personal Computer
(b) The following table shows part of the instruction set for a processor. The processor has one general purpose register, the Accumulator (ACC), and an Index Register (IX). Instruction Op code Explanation (mnemonic) Operand Op code (binary) LDM #n 1100 0001 Immediate addressing. Load number n to ACC. LDD

1100 0010 Direct addressing. Load the contents of the given address to ACC. LDV #n 1100 0011 Relative addressing. Move to the address n locations from the address of the current instruction. Load the contents of this address to ACC. STO

1100 0100 Store the contents of ACC at the given address. DEC 1100 0101 Decrement the contents of ACC. OUTCH 1100 0111 Output the character corresponding to the ASCII character code in ACC. JNE

1110 0110 Following a compare instruction, jump to

if the compare was False. JMP

1110 0011 (Unconditionally) jump to the given address. CMP #n 1110 0100 Compare the contents of ACC with number n.