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    8085 Microprocessor Architecture

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    Hritwik Ghosh
    The document describes the architecture of the 8085 microprocessor. It discusses the main components which include the ALU, control logic, registers, memory, and I/O interfaces. It then focuses on the registers within the 8085 including the general purpose registers (B, C, D, E, H, L), accumulator, program counter, stack pointer, and flag register. It provides details on the purpose and functionality of each register.

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    8085 Microprocessor Architecture

    Uploaded by

    Hritwik Ghosh
    21 views13 pages
    The document describes the architecture of the 8085 microprocessor. It discusses the main components which include the ALU, control logic, registers, memory, and I/O interfaces. It then focuses on the registers within the 8085 including the general purpose registers (B, C, D, E, H, L), accumulator, program counter, stack pointer, and flag register. It provides details on the purpose and functionality of each register.

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    REGISTER

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    The document describes the architecture of the 8085 microprocessor. It discusses the main components which include the ALU, control logic, registers, memory, and I/O interfaces. It then focuses on the registers within the 8085 including the general purpose registers (B, C, D, E, H, L), accumulator, program counter, stack pointer, and flag register. It provides details on the purpose and functionality of each register.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    21 views13 pages

    8085 Microprocessor Architecture

    Uploaded by

    Hritwik Ghosh
    The document describes the architecture of the 8085 microprocessor. It discusses the main components which include the ALU, control logic, registers, memory, and I/O interfaces. It then focuses on the registers within the 8085 including the general purpose registers (B, C, D, E, H, L), accumulator, program counter, stack pointer, and flag register. It provides details on the purpose and functionality of each register.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 13

    8085 Microprocessor Architecture

    1
    System Architecture
    The typical processor system consists of:

     CPU (central processing unit)


     ALU (arithmetic-logic unit)
     Control Logic
     Registers, etc…
     Memory
     Input / Output interfaces

    Interconnections between these units:

     Address Bus
     Data Bus
     Control Bus

    2
    3
    Register Section

    4
    The 8085: Registers

    5
    The 8085: Registers
    General Purpose Registers

     Six general purpose 8-bit registers: B, C, D, E, H, L

     They can also be combined as register pairs to


    perform 16-bit operations: BC, DE, HL

     Registers are programmable (data load, move, etc.)

    Special Purpose Registers

     Accumulator, Program Counter, Stack Pointer, Flag Register

    6
    ACCUMULATOR(ACC)

     The accumulator is an 8-bit register :Used for


    arithmetic / logic operations – the result is always
    stored in the accumulator.
     ACC holds one of the source of the operand and also
    destination of the result.

    7
    PROGRAM COUNTER (PC)
    a 16 bit register, used to store the next
    address of the operation code to be fetched
    by the CPU.
     Purpose of PC in a Microprocessor
     to store address of next instruction to be
    executed.

    8
    STACK POINTER (SP)
     Stack Pointer(SP)(16) – Points to a
    memory location in R/W memory, called
    the stack
     The stack is configured as a data
    structure that grows downward from high
    memory to low memory.
     At any given time, the SP holds the 16-bit
    address of the next free location in the
    stack.

    9
    FLAG REGISTER(F)

     The ALU includes five flip-flops, which are set or reset


    after an operation according to data conditions of the
    result in the accumulator and other registers
     They are called Zero (Z), Carry (CY), Sign (S), Parity
    (P), and Auxiliary Carry (AC) flags

     If the sum in the accumulator is larger than eight bits,


    the flip-flop uses to indicate a carry -- called the Carry
    flag (CY) – is set to one
     When an arithmetic operation results in zero, the flip-
    flop called the Zero (Z) flag is set to one
    10
    FLAG REGISTER

     If the result in the accumulator is negative, then Sign


    flag (S) – is set to one
     If the result in the accumulator holds even no. of 1’s,
    then Parity flag (P) – is set to one
     If carry is occurred in D3 (lower nibble ) and passed to
    D4 bit , then Auxiliary Carry (AC) flag is set to one.

    11
    FLAGS

    12
    INSTRUCTION REGISTER/DECODER

     The instruction register and the decoder are


    considered as a part of the ALU
     The instruction register is a temporary storage for the
    current instruction of a program
     The decoder decodes the instruction and establishes
    the sequence of events to follow

    13

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