Ch 17: Secondary Storage and Device Drivers

Comprehensive capstone module covering cylinder-head-sector addressing, low-level disk sector reading/writing via INT 13h, boot sector layout, and assembling character device drivers.

183 Questions183 MCQs0 Short Questions0 Long Questions

🎯 Exam Practice Papers

CS401 - Computer Architecture and Assembly Language Programming Examination Practice

Timed practice exam simulation for CS401 - Computer Architecture and Assembly Language Programming.

Showing 21 – 30 of 183 Questions

Page 3 of 19

Q21

❓ MCQ📘 CS401📑 Lec 17🏷️ Byte vs Word String Variants (STOSB vs STOSW)Easy🔁⭐💡📄🎓VU🏛️VU

How do string instruction variants (such as STOSB vs STOSW) differ in operand data size and index register pointer adjustments when the Direction Flag (DF) is cleared (CLD)?

💻 assembly Snippet

stosb
stosw

A.STOSB transfers 1 byte and increments index registers by 1; STOSW transfers 1 word (2 bytes) and increments index registers by 2
B.STOSB transfers 1 word and decrements index registers by 1; STOSW transfers 1 byte and decrements index registers by 2
C.STOSB transfers 1 byte and decrements index registers by 2; STOSW transfers 1 word and increments index registers by 1
D.STOSB and STOSW both transfer 2 bytes but adjust SP instead of DI

Q22

📝 Short Q📘 CS401📑 Lec 17🏷️ Direction Flag (DF) and Auto-Increment/Auto-Decrement ModesEasy🔁⭐💡📄🎓VU🏛️VU

Explain how the Direction Flag (DF) controls the execution direction of string processing instructions in 8088 assembly language. Contrast auto-increment mode ('CLD') with auto-decrement mode ('STD').

💻 assembly Snippet

cld
std

Q23

❓ MCQ📘 CS401📑 Lec 17🏷️ String Instruction Destination Memory Addressing RulesEasy🔁⭐💡📄🎓VU🏛️VU

Which segment-offset register pair is used as the implicit memory destination pointer in 8088 string instructions, and can its segment register be overridden?

A.DS:SI, and segment override is allowed
B.ES:DI, and segment override is NOT allowed
C.DS:DI, and segment override is allowed
D.ES:SI, and segment override is NOT allowed

Q24

📝 Short Q📘 CS401📑 Lec 17🏷️ STOS Instruction and REP Prefix MechanicsMedium🔁⭐💡📄🎓VU🏛️VU

Describe the operation of the STOS (Store String) instruction when combined with the REP hardware prefix, specifying source operands, destination registers, counter registers, and index pointer updates.

💻 assembly Snippet

mov ax, 0xb800
mov es, ax
mov di, 0
mov ax, 0x0720
mov cx, 2000
cld
rep stosw

Q25

📝 Short Q📘 CS401📑 Lec 17🏷️ LODS Instruction Mechanics and Inapplicability of REP PrefixMedium🔁⭐💡📄🎓VU🏛️VU

Explain the mechanics of the LODS (Load String) instruction in 8088 assembly language. Why is the hardware REP prefix generally NOT used with LODS?

💻 assembly Snippet

lodsb
lodsw

Q26

📝 Short Q📘 CS401📑 Lec 17🏷️ SCAS Instruction and String Length Calculation using REPNEHard🔁⭐💡🌟📄🎓VU🏛️VU

Explain the operation of the SCAS (Scan String) instruction and describe how combining SCAS with the REPNE (Repeat While Not Equal) prefix allows programmers to find characters or calculate string lengths.

💻 assembly Snippet

mov al, 0
mov cx, 0xffff
repne scasb

Q27

❓ MCQ📘 CS401📑 Lec 17🏷️ REP Prefix Counter Decrement BehaviorEasy🔁⭐💡📄🎓VU🏛️VU

How does the hardware REP prefix decrement the counter register (CX) during the execution of string instructions for word-sized operands compared to byte-sized operands?

💻 assembly Snippet

rep stosw

A.REP always decrements CX by 1 per repetition loop regardless of byte or word operand size
B.REP decrements CX by 1 for byte string instructions and by 2 for word string instructions
C.REP decrements CX by 2 for byte string instructions and by 1 for word string instructions
D.REP decrements CX based on the value stored in the Direction Flag (DF)

Q28

📝 Short Q📘 CS401📑 Lec 17🏷️ Overlapping Memory Block Copying and Direction Flag ControlHard🔁⭐💡📄🎓VU🏛️VU

Explain the overlapping memory block problem during block copy operations (MOVS) in 8088 assembly language, and describe how the Direction Flag (DF) is utilized to prevent data corruption.

💻 assembly Snippet

std
rep movsb

Q29

📝 Short Q📘 CS401📑 Lec 17🏷️ CMPS Instruction Mechanics and Block ComparisonMedium🔁⭐💡📄🎓VU🏛️VU

Explain the operation of the CMPS (Compare String) instruction in 8088 assembly language, specifying register roles, flag modifications, and usage with conditional repeat prefixes REPE and REPNE.

💻 assembly Snippet

repe cmpsb

Q30

❓ MCQ📘 CS401📑 Lec 17🏷️ Conditional Repeat Prefixes (REPE vs REPNE) Termination ConditionsEasy🔁⭐💡📄🎓VU🏛️VU

Which combination of conditions causes the 'REPE CMPSB' instruction to terminate execution loop in 8088 assembly language?

💻 assembly Snippet

repe cmpsb

A.When a mismatch is found (Zero Flag ZF = 0) OR when CX decrements to 0
B.When a match is found (Zero Flag ZF = 1) OR when CX decrements to 0
C.Only when the Direction Flag (DF) is set to 1
D.When an overflow interrupt occurs during subtraction

Ch 17: Secondary Storage and Device Drivers

CS401 - Computer Architecture and Assembly Language Programming Examination Practice

Mid Term Examination

Final Term Examination

CS401 - Computer Architecture and Assembly Language Programming Examination Practice

Mid Term Examination

Final Term Examination

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