Subject: Computer Organization (CS401)
Exam Type: Theory
Semester: 4th
Time: 3 Hours
Maximum Marks: 100
Section A – Short Answer Questions (10 × 2 = 20 Marks)
This section tests your conceptual knowledge of digital logic, control units, memory, and I/O systems through short definitions or explanations.
Topics covered:
Multiplexer: Function and applications in data selection.
24-bit register representation: Converting decimal 195 into BCD.
Self-complementing BCD codes: Meaning and examples.
Microcode: Concept and purpose in control unit design.
Wide branch addressing: Explanation and use.
RISC architecture: Key features and advantages.
Indirect addressing: Explanation with an example.
Write-back method: Function in cache memory operations.
Flash memory: Definition and characteristics.
Asynchronous data transfer: Concept and use in communication between mismatched systems.
Section B – Descriptive & Problem-Based Questions (5 × 10 = 50 Marks)
This section focuses on numerical problems, logic design, and hardware implementation concepts.
Key questions include:
Performing logic micro-operations on registers (e.g., converting binary 11011001 using selective set/complement operations).
Hardware implementation of selective set and complement operations.
Writing assembly-style programs to evaluate arithmetic expressions like
X=(A−B+C×(D×E−F))/(G+H×K)X = (A - B + C \times (D \times E - F)) / (G + H \times K)X=(A−B+C×(D×E−F))/(G+H×K)
for both general register and accumulator type computers.
Explanation of I/O bus architectures.
Hardwired control and DMA (Direct Memory Access) working.
Serial communication and Input/Output Processor (IOP) short notes.
Virtual memory management problem: Given page and block table, identify virtual addresses that cause page faults.
Decoder circuit design: 2-to-4 line decoder using NAND gates with truth table and block diagram.
Section C – Long Analytical Questions (2 × 15 = 30 Marks)
These are detailed questions on computer control mechanisms, I/O systems, and number system conversions.
DMA Controller: Draw its block diagram.
Explain the bidirectional nature of read/write control lines.
Discuss the working of an I/O Processor.
Asynchronous Data Transfer:
Explain the strobe control and handshaking mechanisms.
Perform number system conversions:
(100100)2=(?)10(100100)_2 = (?)_{10}(100100)2=(?)10
(235.41)7=(?)13(235.41)_7 = (?)_{13}(235.41)7=(?)13
Microinstruction Format & Processor Organization:
Show how a 9-bit microoperation field can be divided to specify 46 different actions.
Explain how a processor executes instructions, defining internal functional units and their interconnections.
Major Topics Covered
Logic circuits (multiplexer, decoder, microoperations)
Control unit design (hardwired, microprogrammed)
Memory systems (cache, flash, virtual memory, DMA)
Addressing modes and instruction execution
Asynchronous data transfer methods
I/O architecture and processor organization
Microinstruction formats and control sequencing
Purpose of the Paper
This exam tests your understanding of how a computer’s hardware components interact, how instructions are executed, and how data transfers occur between the CPU, memory, and peripherals.
It blends theoretical concepts (like control unit design) with practical logic design problems (like decoder construction and register operations).
