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Contents

Microprocessors

8085 Architecture

8085 Architecture Overview 8085 Pin Description Timing Diagrams Control Signals Demultiplexing Bus

8085 Instructions

Addressing Modes Instruction Set Groups Stack Instructions Rotate Instructions 16-bit Arithmetic

8085 Programming

Assembly Language Basics Arithmetic Programs Looping and Indexing Stack and Subroutines BCD Arithmetic Time Delay Loops Code Conversion

8086 Architecture

8086 Architecture Memory Segmentation 8086 Pin Diagram Flag Register 8086 Instruction Queue

8086 Programming

8086 Addressing Modes 8086 Instruction Set String Instructions Interrupts DOS Function Calls BIOS Interrupts Macros vs Procedures Assembler Directives

Peripheral Interfacing

Memory Interfacing IO Interfacing 8255 PPI 8259 PIC 8253/54 Timer 8237 DMA 8251 USART 7 Segment Display Interface Stepper Motor Interface Keyboard Interfacing

Modern Processors

Evolution to Pentium Protected Mode Pipelining Cache Memory Virtual Memory Branch Prediction Multi-core Processors Hyper-Threading SIMD Instructions

Other Topics

RISC vs CISC Microcontroller Difference Bus Standards

Other Subjects

Analog Electronics Digital Electronics Signals & Systems Control Systems Electromagnetic Theory Digital Communication Analog Communication Network Analysis VLSI Design Verilog HDL Power Electronics Embedded Systems DSP Electronic Devices

Section Progress70%

7 of 10 articles

8251 USART

Universal Synchronous Asynchronous Receiver Transmitter.

Updated: 19 March 2026

11 min read

#Microprocessors

8251 USART Quiz

Test your understanding of 8251 USART synchronous and asynchronous modes, baud rate, and control words.

Question 1 of 3

Q1.In asynchronous mode, the 8251 is programmed with a baud rate factor of 16. If the transmitter clock (TxC) frequency is 153.6 kHz, what is the actual baud rate for transmission?

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Programmable Peripheral Interface, modes.

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8259 PIC

Priority Interrupt Controller, cascading.

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