In 8085 microprocessor with memory-mapped I/O which of the following is true?

This question was previously asked in
ESE Electrical 2015 Paper 2: Official Paper
View all UPSC IES Papers >
  1. I/O devices have 16 bit addresses
  2. I/O devices are accessed during IN and OUT instructions
  3. There can be a maximum of 256 input and 256 output devices
  4. Logic operations cannot be performed

Answer (Detailed Solution Below)

Option 1 : I/O devices have 16 bit addresses
Free
ST 1: UPSC ESE (IES) Civil - Building Materials
6.5 K Users
20 Questions 40 Marks 24 Mins

Detailed Solution

Download Solution PDF

Microprocessors normally use two methods to connect external devices:

  • Memory-mapped I/O
  • Port/Peripheral Mapped I/O

Memory-Mapped I/O:

  • 16-bit device address
  • Data transfer between any general-purpose register and I/O port
  • The memory map (64K) is shared between the I/O device and system memory
  • More hardware is required to decode 16-bit address
  • Arithmetic or logic operation can be directly performed with I/O data

Memory-mapped I/O is mapped into the same address space as program memory and/or user memory and is accessed in the same way. Port mapped I/O uses a separate, dedicated address space and is accessed via a dedicated set of microprocessor instructions.

26 June 1

Peripheral Mapped I/O:

  • 8-bit device address
  • Data is transferred only between the accumulator and I.O port
  • The I/O map is independent of the memory map; 256 input device and 256; The output device can be connected
  • Less hardware is required to decode 8-bit address
  • Arithmetic or logical operation cannot be directly performed with I/O data
Latest UPSC IES Updates

Last updated on Jul 2, 2025

-> ESE Mains 2025 exam date has been released. As per the schedule, UPSC IES Mains exam 2025 will be conducted on August 10. 

-> UPSC ESE result 2025 has been released. Candidates can download the ESE prelims result PDF from here.

->  UPSC ESE admit card 2025 for the prelims exam has been released. 

-> The UPSC IES Prelims 2025 will be held on 8th June 2025.

-> The selection process includes a Prelims and a Mains Examination, followed by a Personality Test/Interview.

-> Candidates should attempt the UPSC IES mock tests to increase their efficiency. The UPSC IES previous year papers can be downloaded here.

More Microprocessors Questions

Get Free Access Now
Hot Links: teen patti 500 bonus teen patti tiger teen patti joy mod apk teen patti club apk teen patti apk