Ch 09: Software Interrupts and DOS/BIOS Services

Covers IVT structure (256 vectors x 4 bytes each = 1KB), pushing flags and CS:IP during interrupt invocation, hooking existing software interrupts, and invoking DOS function calls for disk and character I/O.

174 Questions174 MCQs0 Short Questions0 Long Questions

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CS401 - Computer Architecture and Assembly Language Programming Examination Practice

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

Showing 171 – 174 of 174 Questions

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Q171

❓ MCQ📘 CS401📑 Lec 9🏷️ 9.2. DOS File Management ServicesMedium🔁⭐💡📄🎓VU🏛️VU

When executing MS-DOS system call INT 0x21 with AH = 0x3D (Open Existing File), how does the operating system indicate that the file could not be opened?

💻 assembly Snippet

mov ah, 0x3d  ; Open file
mov al, 0     ; Read access
mov dx, filename
int 0x21
jc file_error  ; Jumps if CF = 1

A.Carry Flag is set (CF = 1) and an error code is returned in AX
B.Zero Flag is set (ZF = 1) and AX = 0
C.Interrupt 0x24 is generated immediately
D.AX is set to 0xFFFF without changing flags

Q172

❓ MCQ📘 CS401📑 Lec 9🏷️ 9.2. DOS File Management ServicesMedium🔁⭐💡📄🎓VU🏛️VU

When executing MS-DOS system call INT 0x21 with AH = 0x3D (Open File), if the file cannot be opened, which status flag is set?

💻 assembly Snippet

mov ah, 0x3d
int 0x21
jc file_error  ; Jumps if CF = 1

A.Carry Flag is set (CF = 1)
B.Carry Flag is cleared (CF = 0)
C.Zero Flag is set (ZF = 1)
D.Zero Flag is cleared (ZF = 0)

Q173

❓ MCQ📘 CS401📑 Lec 9🏷️ 9.1. Program Segment PrefixMedium🔁⭐💡📄🎓VU🏛️VU

When executing a COM file, at which offset within the Program Segment Prefix (PSP) does the text of the first command-line parameter begin?

A.0x80
B.0x82
C.0x84
D.0x86

Q174

❓ MCQ📘 CS401📑 Lec 9🏷️ 9.3. BIOS Disk Services (INT 13h)Easy🔁⭐💡📄🎓VU🏛️VU

In BIOS disk interrupt service INT 0x13, subservice AH = 0x03 is used to:

💻 assembly Snippet

mov ah, 0x03  ; Write disk sectors
int 0x13

A.Read disk sectors
B.Write disk sectors
C.Reset disk system
D.Get drive parameters

Ch 09: Software Interrupts and DOS/BIOS Services

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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