CS609 — System Programming — Midterm Past Papers & Solved MCQs

Q1. stores the base address for LPT1

• A.40:00H✓ Correct
• B.40:04H
• C.200H
• D.40:1AH

Q2. In interrupt 17H, if DX register contains zero, then I/O will be performed on .

• A.LPT1✓ Correct
• B.LPT0
• C.LPT3
• D.LPT4

Q3. The speed of Microprocessor depends upon

• A.Memory
• B.Frequency of Clock signal✓ Correct
• C.BIOS
• D.Operating system

Q4. Interrupt _____ is empty: we can use its vector as a flag.

• A.13H
• B.15H
• C.65H✓ Correct
• D.21H

Q5. The Interrupt no. 65H is used

• A.by DOS
• B.by BIOS
• C.neither by DOS nor by BIOS✓ Correct
• D.both by DOS and BIOS

Q6. Timer interrupt is invoked by means of .

• A.Hardware✓ Correct
• B.Software
• C.Hardware and Software
• D.Operating System Call

Q7. In Real Time Clock, the Status is used to specify the date time formats.

• A.Register B✓ Correct
• B.Register C
• C.Register D
• D.Register E

Q8. The UART device uses for error detection.

• A.Checksum
• B.CRC Check
• C.Parity Bit✓ Correct
• D.LRC Check

Q9. BIOS data area starts from .

• A.40:00H✓ Correct
• B.40:1EH
• C.40:3DH
• D.40:FFH

Q10. The registers Flags, are pushed on stack after execution of INT instruction and execution branches to the interrupt procedure.

• A.CS and IP✓ Correct
• B.CS and SP
• C.IP and DS
• D.DS and SP

Q11. What is output of the following program; #include<DOS.H> union REGS regs; void main(void) { regs.h.al = 0x99; }

• A.0
• B.0099✓ Correct
• C.00
• D.99

Q12. Parameters in interrupts are passed through

• A.stack
• B.registers✓ Correct
• C.array
• D.link lists

Q13. The printer interface uses the .

• A.IRQ 6✓ Correct
• B.IRQ 1
• C.IRQ 2
• D.IRQ 7

Q14. While performing programmed I/O on the printer using BIOS service, we must check _____ of Status Byte to see if printer is busy or not.

• A.Most Significant Bit✓ Correct
• B.Least Significant Bit
• C.Fourth Bit
• D.Tenth Bit

Q15. If printer is then printer sends back the ACK signal to the printer interface

• A.idle✓ Correct
• B.busy
• C.Out-of-paper
• D.in paper jam error

Q16. REGS is a

• A.Union✓ Correct
• B.Struct
• C.Interrupt
• D.Service

Q17. Every ISR (Interrupt Service Routine) should check service number in _____ register and then perform the function accordingly

• A.AH✓ Correct
• B.AL
• C.BH
• D.BL

Q18. The register which is not available in the UART device is

• A.Receiver Buffer Register
• B.Interrupt Focus Register✓ Correct
• C.Line Status Register
• D.Interrupt ID Register

Q19. DCE is

• A.Data Communication Equipment✓ Correct
• B.Dual Communication Equipment
• C.Data Clearing Equipment
• D.Data Control Equipment

Q20. In the Counter Register of Interval Timer, bit number 3 changes its value between 0 and 1 within ____clock cycles

• A.1
• B.2✓ Correct
• C.3
• D.4

Q21. Operating system information is in a special block on disk which is called

• A.Interrupt Block
• B.OS Block
• C.Secondary Block
• D.Boot Block✓ Correct

Q22. The PPI acts as an interface between the CPU and a parallel .

• A.I/O device✓ Correct
• B.Controller
• C.Control bus
• D.Data bus

Q23. All Interval Timer channels are _____ bits wide.

• A.8
• B.16✓ Correct
• C.32
• D.64

Q24. In interrupt interception with software interrupts, the original interrupt can be invoked ____

• A.At the start of ISR
• B.At the end of ISR
• C.In the middle of ISR
• D.Anywhere in ISR✓ Correct

Q25. _____ is used to set date.

• A.1A/02H
• B.1A/03H✓ Correct
• C.1A/04H
• D.1A/05H

Q26. Frequency of clock signal measures the speed of the

• A.BIOS
• B.CPU✓ Correct
• C.Address Bus
• D.System Clock

Q27. To store each character in keyboard buffer ____ bytes are required.

• A.1
• B.2✓ Correct
• C.3
• D.4

Q28. In the context of COM ports. AH register is treated as a .

• A.Line Status Register
• B.Modem Status Register
• C.Control Register✓ Correct
• D.Command Register

Q29. How many Interrupts can be addressed via Interrupt Vector Table?

• A.256✓ Correct
• B.512
• C.1024
• D.2048