8085 Microprocessor: Foundation of Microprocessor by Intel

Trace Intel's microprocessor evolution from 4004 to core i3–i9, highlighting transistors, clock speeds, and memory addressing. See why studying 8085 and 8086 builds essential fundamentals for understanding today's complex processors.

Discover how a computer centers on a single-chip processor with an ALU, resistor array, and control unit that executes instructions via fetch-decode-execute, and interfaces memory with input and output devices.

Differentiate microprocessor and microcontroller: microprocessors are CPUs with memory and I/O for general tasks, while microcontrollers integrate CPU, memory, I/O, and timers on one chip for specific, low-cost applications.

Interface external memory with the 8085 microprocessor to load and execute programs stored in rom or ram, and show how compiler and assembler convert code into machine code.

Learn how the 8085 microprocessor executes programs from external memory, using program counter and the three-phase instruction cycle: fetch, decode, and execute.

Learn to count memory in 8085 by identifying address lines and data lines for memory sizes, and understanding how bytes and words map to hex and binary.

Explore how higher level languages like C and C++ are compiled into machine language, while assembly uses mnemonics and an assembler translates to 8085 machine code.

Explore the architecture of the 8085 microprocessor, detailing its programming model, registers and accumulator, program counter, memory interfacing with multiplexed address/data lines, and timing, control, and the ALU.

Explore the 8085 pin diagram, detailing power and clock pins, 50% duty cycle, 16-bit address/data buses, ALE and multiplexed AD lines, control signals, reset, ready, serial I/O, interrupts, and DMA.

Understand buses in the 8085 microprocessor: 16 address lines, 8 data lines, and control lines, with unidirectional address/control and bidirectional data for memory, input, and output.

Understand the 8085 flag register and how its five active bits: sign, zero, auxiliary carry, parity, and carry update after each instruction, illustrated with an add example.

Learn the 8085 programming model by examining the accumulator as the ALU's default operand, the flag and general purpose registers, and how the program counter and stack pointer drive execution.

Generate memory read, memory write, IO read, and IO write control signals for the 8085 using IO memory bar, read bar, and write bar, with active-low operation and decoder-based options.

Demonstrate address data demultiplexing in the 8085 by using time multiplexing, an address latch enable, and a 74373 latch to separate ad0–ad7 into address and data.

Explore the 8085 microprocessor operation types, including microprocessor initiated, internal, and peripheral initiated operations, with memory read/write, input/output read/write, and related timing, decoding, and DMA concepts.

Memory mapped io treats io devices as memory using 16 address lines for 64k addresses. Io mapped io uses 8 address lines for up to 256 devices with simpler hardware.

Learn the five 8085 machine cycles—opcode fetch, memory read, memory write, I/O read, and I/O write—and how each transfers one byte with defined t-states and timing.

Explain the opcode fetch timing diagram for a one-byte move instruction in the 8085 microprocessor, covering the four t states, address/data multiplexing, and the decode operation in t4.

Demonstrate memory read and memory write operations in the 8085 through three t-state timing (t1–t3), using a 1000 hex address with upper/lower byte addressing, ALE, and data on AD0–AD7.

Explore the timing diagram of the Mvi instruction in the 8085 microprocessor by stepping through opcode fetch and memory read cycles, showing how the accumulator updates to 32 hex.

Learn how the STA store accumulator instruction uses opcode fetch, two memory reads, and a memory write to transfer the accumulator to a specified address, illustrated by timing diagrams.

Examine the 8085 in instruction timing diagram for io mapped io using an eight-bit port 0x05, detailing opcode fetch, memory read, and io read cycles to load the accumulator.

Explore the 8085 out instruction timing diagram, covering opcode fetch, memory read, and I/O write within an I/O mapped I/O setup using port address 05 hex.

Learn how 8085 uses a 16-bit stack pointer to manage stack memory with push and pop, saving the program counter and flags for subroutines and data storage.

learn how 8085 subroutines enable code reuse via call and return, with push and pop of the program counter on the stack, and conditional calls and returns.

Learn how to pass parameters to an 8085 subroutine using the stack, by pushing registers before a call and popping them after.

Learn how the 8085 microprocessor responds to interrupts with a structured interrupt service routine, including executing the current instruction, pushing PC, DI, then jumping to ISR and returning.

Explore software and hardware interrupts in the 8085; software interrupts are instruction-driven and vectored, while hardware interrupts rely on external pins with defined priority and h-trigger or level-trigger.

Explore the 8085 hardware interrupts, including trap, rst7.5, rst6.5, rst5.5, and intr, and learn their priority, edge- and level-triggered behavior, plus masking.

Explore the 8085 interrupt structure, detailing five inputs (trap, 7.5, 6.5, 5.5, intr), their trigger types and priorities, and how EI/DI and masking govern ISR addresses.

Explore sim and rim instructions in the 8085 microprocessor to set and read interrupt masks, enable serial communication, and transmit or receive data.

Learn to generate a 1 kHz square wave on the 8085 microprocessor using the SIM command, transmitting 1010 serial data with precise 0.5 ms high and low delays.

Explore 8085 serial communication using the uart standard, transmitting a byte from memory location 1000 hex, at baud rate 1000, detailing start and stop bits and timing.

Explore the I2C protocol, a two-wire serial bus (SDA and SCL) connecting up to 128 devices with pull-up resistors, addressing, start/stop bits, clock stretching, and multi master slave support.

Explore the SPI protocol, a four-wire serial interface enabling master-slave communication with clocked MOSI and MISO data, using CPOL and CPHA to define the four modes.

Compare I2C and SPI for on-board communication. I2C uses two wires (SDA, SCL) and supports multi-master; SPI uses four wires (MOSI, MISO, SCLK, CS) for higher speed and full duplex.

Explore the uart protocol for serial communication, universal asynchronous receiver transmitter using two wires, no clock, with configurable baud rate, data length, start/stop bits, optional parity, and nrzi coding.

Explore the usb protocol for serial communication, covering versions and connectors, host-slave topology, self-configuring and hot-swappable design, power delivery, plug-and-play, and key limitations.

Explore Rs-232 protocol for serial communication between dte and dce, covering db9 and db25 connectors, handshaking, voltage levels, and the data frame format.

Explore 8085 addressing modes: immediate, resistor, direct, indirect, and implied, with examples showing how operands are specified and transferred.

Explore how the 8085 microprocessor executes one-byte, two-byte, and three-byte instructions through opcode fetch and memory read machine cycles, with examples like dcr, mvi, adi, lda, and lhld.

Master 8085 data transfer instructions, including mov, mvi, lda, sta, lxi, and shld, and understand register, immediate, direct, and indirect addressing using the hl pair and memory.

Explore arithmetic and data-transfer instructions for the 8085 microprocessor, including add, adc, adi, sub, dad, da, inr, inr m, inx, dcr, and dcx, with addressing modes and carry flags.

Master 8085 logical instructions, including and, or, xor, rotate, and compare, applied to the accumulator and memory data. Cover addressing modes, flag effects, machine cycles, and t-states.

Explore branch control in the 8085 microprocessor, including unconditional and conditional jumps, calls, rest instructions, and the role of program counter and interrupts in subroutines.

Learn how the 8085 daa decimal adjustment instruction, after addition, converts binary results to decimal by adjusting the accumulator via nibble checks and adding 0x06 or 0x60.

Compare call and jump in the 8085 microprocessor, explaining how jump transfers control to a label, while call pushes the return address on the stack and enters a subroutine.

Learn to generate delays in 8085 microprocessor by loading count into c, decrementing with dcr c, and looping with jnz, then calculating delay from t-states.

Generates a 0.1 second delay on the 8085 using nested loops and counting, and explains why timers are absent and how to estimate delay with resistor values and t-states.

Design a counter in 8085 that displays 0-9 on port one with a one-second delay, using an hl pair loop and reset after nine.

Learn how to generate a 5 hertz square wave on the 8085 microprocessor using a non-timer approach, with a 0.1 second delay via nested loops and the accumulator out operation.