The Intel (“eighty-eighty-five”) is an 8-bit microprocessor produced by Intel and introduced in It is a software-binary compatible with the more-famous. Microprocessor: It is a programmable electronics chip (Integrated Circuit ( IC)). A single IC has computing and decision making capabilities similar to. In addition to the microprocessor, a personal computer has a keyboard for The AS/ uses the PowerPC microprocessor with its reduced instruction set.

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These instructions are used to perform arithmetic operations such as addition, subtraction, increment or decrement of the content of a register or memory.

The architecture of consists of three main sections, ALU Arithmetic and Logical Unittiming and control unit and Registers shown in the following figure. Rd, data M, data. The Addressing Modes: The 8-bit data is stored in the destination register or memory.

Week 7 Aug 20 35 upvotes. Like larger processors, it has CALL and RET instructions for multi-level procedure calls and returns which can be conditionally executed, like jumps and instructions to save and restore any bit register-pair on the machine stack. INTR can be micropocessor or disabled by using software. Comments Write a comment. All buses are tri-stated and a Hold Acknowledge signal is sent out.

The DMA controller takes control of the buses and transfers data directly between source and destination, thus bypassing the microprocessor. Load H and L registers direct. The contents of the H register provide the high-order address and the contents of the L register microrpocessor the low-order address. It controls micrprocessor serial data communication by using these two instructions: A 1-byte instruction includes the opcode and operand in the same byte.

The zero flag is set if the result of the operation was 0. A bit binary micgoprocessor is called a word in a bit processor. Intel produced a series of development systems for the andknown as the MDS Microprocessor System. The contents of the L register are exchanged with the stack location pointed out by the contents of the stack pointer register.


In a three byte instruction, the first byte specifies the opcode and the following two bytes specify the bit address.

During these transfers, the processor monitors the addresses on the bus and checks if any location modified during DMA operations is cached in the processor. A peripheral micrroprocessor be a LCD display or analog to digital converter or any other.

8085 Microprocessor Study notes for Electronics and Communication

The CPU is held in reset condition until this pin is high. An improvement over the is that the can itself drive a piezoelectric crystal directly connected to it, and a built-in clock generator generates the internal high amplitude two-phase clock signals at half the crystal frequency a 6.

Data bus also carries instructions from memory to the microprocessor. Which exam are you preparing for? Writes data or instruction into memory.

Although the data is still transferred 1 memory microprocesslr at a time from the device, the transfer to main memory now circumvents the CPU because the DMA controller can directly access the memory unit. However, an circuit requires an 8-bit address latch, so Intel manufactured several support chips with an address latch built in. The microprocessor uses this register to sequence the execution of the instructions.

Effective address is calculated by the processor and the contents of the address is used to form a second address. The device then asserts the bus grant ack signal.

MVI A,00 ; Load immediate data into accumulator. The other six registers can be used as independent byte-registers or as three bit register pairs, BC, DE, and Mlcroprocessor or B, D, H, as referred to in Intel documentsdepending on the particular instruction. The size of the address bus determines the size of memory, which can be used.


Microprocessor Study notes for Electronics and Communication

All 2-operand 8-bit arithmetic and logical ALU operations work on the 8-bit accumulator the A register. The stack pointer is also a 16 bit register used as a memory pointer. The contents of register H are exchanged with the contents of register D, and the contents of register L are exchanged with the contents of register E. The parity flag is set according to the parity odd or even of the accumulator. The uses approximately 6, transistors.

Such signals come under this category. The various formats for specifying operands are called the addressing modes. The accumulator stores the results of arithmetic and logical operations, and the flags register bits sign, zero, auxiliary carry, parity, and carry flags are set or cleared according to the results of these operations.

Decoder then takes instruction and decodes or interprets the instruction.

The function of the program counter is to point to the memory address from which the next byte is to be fetched. State signals are provided by dedicated bus control signal pins and two dedicated bus state ID pins named S0 and S1. Size of the microprocedsor bus determines what arithmetic can be done.

The is supplied in a pin DIP package. The Instruction Format: In a two-byte instruction, the first byte specifies the operation code and the second byte specifies the operand. It can be used to store additional data during a program.