PREVIOUS YEAR SOLVED PAPERS - November 2017 Paper 3
- Option : D
- Explanation : AC is auxiliary-Carry flag, CY is Carry flag and Z is Zero flag. All these flags will be affected during arithmetic operation. So, option (D) is correct.
2. In 8085 microprocessor the address bus is of __________ bits.
- Option : C
- Explanation : In 8085 microprocessor 16 bits are used for address bus and 65,536(216 = 65,536) different memory location are possible. So, option (C) is correct.
3. In the architecture of 8085 microprocessor match the following:
| (a) Processing Unit   |  (i) Interrupt |
| (b) Instruction unit  |  (ii) General Purpose Register |
| (c) Storage and Interface unit |  (iii) ALU |
| Â | Â (iv) Timing and Control |
| Â | (a) | (b) | (c) |
| (1) | (iv) | (i) | (ii) |
| (2) | (iii) | (iv) | (ii) |
| (3) | (ii) | (iii) | (i) |
| (4) | (i) | (ii) | (iv) |
- Option : B
- Explanation :
- ALU is the arithmetic logic unit and it involves processing of input into desired output.
- Timing and control instruction are covered in instruction unit of microprocessor.
- There are some general purpose register in storage and interface unit.
- While an interrupt is a signal to the processor which required attention from processor, an interrupt is serviced on the basis of priorty and need.
So, option (B) is correct.
- Option : A
- Explanation : Indexed addressing mode is best suited for accessing an array in contiguous memory location. For detailed information on addressing modes Refer:Addressing_Modes. So, option (A) is correct.
5. Which of the following is correct statement ?
- A
In memory - mapped I/O, the CPU can manipulate I/O data residing in interface registers that are not used to manipulate memory words.
- B
The isolated I/O method isolates memory and I/O addresses so that memory address range is not affected by interface address assignment.
- C
In asynchronous serial transfer of data the two units share a common clock.
- D
In synchronous serial transmission of data the two units have different clocks.
- Option : B
- Explanation :
- The isolated I/O method isolates memory and I/O addresses so that memory address range is not affected by interface address assignment.
- Memory based I/O uses same address space for memory and I/O devices.
- In asynchronous serial transfer of data the two units do not share a common clock.
- In synchronous serial transfer of data the two units share a common clock.
Refer:I/O interface Option (B) is correct.
