Viva Solutions for COA subject

coa-viva.md

COA

Practicals on LOGISIM and TASM.

• Details and Features of 8086 microprocessor

  • enhanced v of 8085 developed by Intek in 1976
  • 16-bit microPro
  • 20 address lines
  • 16 data lines
  • 1mb storage and powerful set of instructions(multiply , divide)
  • 40pin IC
  • Operating Voltage is +5v
  • Operating Frequency 5MHz
  • Instruction Queue stores 6 instruction bytes , for faster processing
  • 29,000 transistors
  • 256 vector interepts
  • Support up to 64K I/O ports

• Architecture

  • Divided intro 2 Parts for Faster Processing
    • BIU : Bus Interface Unit
      • Fetch instructions/data from memory
      • Write Data to Memory and Ports
      • Handles all transfers of data and addresses on the buses for the EU
    • EU : Execution Unit
      • decodes and execute instrutions
      • tells BUI where to fetch instructions from

• Pin Functions

  • AD0 - AD15 : Address Data Bus, Low Order Addr Bus
  • A16 - AD19 : High Order Addr Bus
  • S0 , S1 , S2 : Status Pins

• Memory segmentation

  • Has 4 16-bit special purpose registers
    • Code Segment: addressing memory location in the code segment of the memory, where the executable program is stored
    • Data Segment: points to the data segment of the memory where the data is stored
    • Stack Segment: used to store Stack Segment
    • Extra Segment: refers to a segment in the memory which is another data segment in the memory

• Memory banking

  • used to access two consecutive memory locations in one cycle divided in 2 parts Even Bank and Odd Bank
    • Even Bank: contains even address , gives lower bytes
    • Odd Bank: contains odd address , gives higher bytes

• Minimum Mode Operation

  • In a minimum mode 8086 system, the microprocessor 8086 is operated in minimum mode by strapping its MN/MX' pin to logic1
  • All the control signals are given out by the microprocessor chip itself.

• Maximum Mode Operation

  • In maximum mode, the 8086 is operated by strapping the MN/MX’ pin to ground
  • There may be more than one microprocessor in the system configuration

• 8288 bus controller

  • generate relevant signals for interfacing memory / IO devices in Max. Mode
  • Necesary control signals are generated by 8288

• Demultimplexing of AD0-A19/S6

  • Process of Seperating Address and data pins AD0-AD15 , A16/S3 - A19/S6
  • ALE (Address Latch Enable) is used for this process

• 8284 clock generator

  • provides a stable clock to the processor
  • syncZn of mutiple clock signals
  • resetting to the processor along with clock signals

• Assembler directives

  • instruct the assembler to perform instructions
  • define symbol values
  • reserve and initialize storage spaces
  • ASSUME: segment name to the assembler , ASSUME CS:code
  • DB (Define Byte): define a 1byte variable , SUM DB 0
  • DW (Define Word) : allocate 2bytes
  • DD (Double Word) : store 4bytes
  • DQ (Quad Word): stores 8bytes
  • DT (Ten Bytes) : 10 bytes

• Registers

  • Are temporary Data Storage build for CPU

  1. General Data Registers

     • AX : accumulator, and preferred for most operations.
     • BX : base register, typically used to hold the address of a procedure or variable.
     • CX : count register, typically used for looping.
     • DX : data register, typically used for multiplication and division.

  2. Segment Registers

     • Code Segment: addressing memory location in the code segment of the memory, where the executable program is stored
     • Data Segment: points to the data segment of the memory where the data is stored
     • Stack Segment: used to store Stack Segment
     • Extra Segment: refers to a segment in the memory which is another data segment in the memory

  3. Pointers and Index Registers

     • IP : Instruction pointer
     • BP : Base pointer
     • SP: Stack pointer
     • SI : Source index
     • DI : Destination index

  4. Flag Register

     • results of the computations in the ALU
     1. SF (Sign Flag): This flag is set, when the result of any computation is negative
     2. ZF (Zero Flag)
     3. Parity Flag
     4. Carry Flag
     5. Auxliary Carry Flag

• DOS interrupt and its functions for AH= 21h/09h/01h

COA Video: https://youtu.be/afQGZNh8hE4