Transcript intel 8085
created by :Gaurav Shrivastava contact:[email protected] INTEL 8085 created by :Gaurav Shrivastava contact:[email protected] ORGANIZATION OF A MICROPROCESSOR-BASED SYSTEM (COMPUTER) CPU – Central Processing Unit Memory I/O ROM – Read Only Memory RAM – Random Access Memory Keyboard Display Device Clock – Square Wave Oscillator (Timing) System Bus created by :Gaurav Shrivastava contact:[email protected] Microprocessor (CPU) Programmable integrated device (silicon chip) that has computing & decision making capabilities Communicates & operates in binary numbers 0 & 1, called bits Has a fixed set of instructions in the form of binary patterns – machine language Difficult for humans to remember machine language – each instruction is represented using abbreviated names (mnemonics) created by :Gaurav Shrivastava contact:[email protected] Memory Symbolic representation Word length 8 bit FFFF FFFE Instruction 1 Instruction 2 Instruction 2 1 word instruction 2 word instruction 64KByte 0001 0000 address Word: no. of bits micro-P recognizes and processes at a time ( 4 - 64bit ). Instruction: combination of bit patterns with specific meaning known to micro-P. Program: Set of all instructions. created by :Gaurav Shrivastava contact:[email protected] I/O Microprocessor’s connection to the outside world Input: Keyboard, mouse Output: Monitor, printer created by :Gaurav Shrivastava contact:[email protected] System Bus – wires connecting memory & I/O to microprocessor Address Bus Unidirectional Identifying peripheral or memory location Data Bus Bidirectional Transferring data Control Bus Synchronization signals Timing signals Control signal created by :Gaurav Shrivastava contact:[email protected] Actions performed by microprocessor: CPU – Memory CPU – I/O Data Processing Arithmetic operations Logical operations Control Jump Interrupts created by :Gaurav Shrivastava contact:[email protected] BASIC CONCEPTS OF MICROPROCESSORS Differences between: Microcomputer – a computer with a microprocessor as its CPU. Includes memory, I/O etc. Microprocessor – silicon chip which includes ALU, register circuits & control circuits Microcontroller – silicon chip which includes microprocessor, memory & I/O in a single package. created by :Gaurav Shrivastava contact:[email protected] Differences between: High level language Assembly language Machine language swap (int v[], int k) {int temp; temp = v[k]; v[k] = v[k+1]; v[k+1] = temp; } swap; muli $2, $5,4 add $2, $4,$2 lw $15, 0($2) lw $16, 4($2) C compiler High Level Languange (in C) 00011100011100 01111000011100 11110000111001 01101011001001 Assembler Assembly Languange Machine Language created by :Gaurav Shrivastava contact:[email protected] ARCHITECTURE OF INTEL 8085 MICROPROCESSOR created by :Gaurav Shrivastava contact:[email protected] INTEL 8085 MICROPROCESSOR Microprocessor consists of: Control unit: control microprocessor operations. ALU: performs data processing function. Registers: provide storage internal to CPU. Interrupts Internal data bus created by :Gaurav Shrivastava contact:[email protected] Registers General Purpose Registers B, C, D, E, H & L (8 bit registers) Can be used singly Or can be used as 16 bit register pairs BC, DE, HL H & L can be used as a data pointer (holds memory address) Special Purpose Registers Accumulator (8 bit register) Store 8 bit data Store the result of an operation Store 8 bit data during I/O transfer created by :Gaurav Shrivastava contact:[email protected] Flag Register 8 bit register – shows the status of the microprocessor before/after an operation S (sign flag), Z (zero flag), AC (auxillary carry flag), P (parity flag) & CY (carry flag) D7 D6 D5 D4 D3 D2 D1 D0 S Z X AC X P X CY Sign Flag Used for indicating the sign of the data in the accumulator The sign flag is set if negative (1 – negative) The sign flag is reset if positive (0 – positive) created by :Gaurav Shrivastava contact:[email protected] Zero Flag Is set if result obtained after an operation is 0 Is set following an increment or decrement operation of that register Carry Flag 10110011 + 01001101 --------------1 00000000 Is set if there is a carry or borrow from arithmetic operation 1011 0101 + 0110 1100 --------------Carry 1 0010 0001 1011 0101 - 1100 1100 --------------Borrow 1 1110 1001 created by :Gaurav Shrivastava contact:[email protected] Auxillary Carry Flag Is set if there is a carry out of bit 3 1011 0101 + 0110 1100 --------------1 0010 0001 Parity Flag Is set if parity is even Is cleared if parity is odd created by :Gaurav Shrivastava contact:[email protected] 16 – Bit Registers Program Counter A pointer to the next instruction to be executed Contains the 16-bit memory address of the next instruction Updated after processor has fetched the instruction Stack Pointer Stack – an area in memory in which temporary info is stored Stack – FILO (First In Last Out) basis Holds the address of the top of the stack created by :Gaurav Shrivastava contact:[email protected] NON PROGRAMMABLE REGISTERS Instruction Register & Decoder Instruction is stored in IR after fetched by processor Decoder decodes instruction in IR Internal Clock generator 3.125 MHz internally 6.25 MHz externally created by :Gaurav Shrivastava contact:[email protected] BASIC WORKING OF A MICROPROCESSOR Instructions are stored sequentially in memory Microprocessor Fetches instruction from memory Decodes instruction Executes instruction created by :Gaurav Shrivastava contact:[email protected] INTERRUPTS OF 8085 MICROPROCESSOR Maskable Interrupts Microprocessor can ignore or delay interrupt request INTR – General purpose interrupt RST 5.5, RST 6.5, RST 7.5 – Restart interrupts, higher priorities Nonmaskable Interrupts Enabled by default Cannot be disabled Microprocessor must respond to it immediately TRAP – highest priority created by :Gaurav Shrivastava contact:[email protected] GROUPING OF SIGNALS OF 8085 MICROPROCESSOR Power supply and frequency signals Address bus signals Data bus signals Control and status signals Externally initiated signals & external signal acknowledgement Serial I/O port signals created by :Gaurav Shrivastava contact:[email protected] ADDRESS BUS SIGNALS, DATA BUS SIGNALS AD0-AD7, A8-A15 16 address lines – 2 sets Most significant bits (A8-A15) – single directional Least significant bits (AD0-AD7) – bidirectional Multiplexed with the bits of bi-directional data bus It is used as both address and data bus created by :Gaurav Shrivastava contact:[email protected] CONTROL AND STATUS SIGNALS Status_lines: IO/M Differentiate I/O and memory applications High – I/O Low – Memory S1, S0 – status signals, to indicate the type of machine cycle in progress Control lines: _ _ __ RD, WR & INTA RD – data on the data bus to be read into processor WR – data on the data bus to be written to processor INTA – acknowledge an INTR interrupt created by :Gaurav Shrivastava contact:[email protected] EXTERNALLY INITIATED SIGNALS & SIGNAL ACKNOWLEDGEMENT Initiated signals Reset In – reset CPU Hold – suspend CPU operation Ready – CPU go into wait state, to sync with slower devices Signal acknowledgement Reset out – high once CPU is rest HLDA – acknowledges hold signal created by :Gaurav Shrivastava contact:[email protected] created by :Gaurav Shrivastava contact:[email protected]