Search Results for – "Direct Memory Access"

Memory Interfacing in 8085

Memory Interfacing in 8085: Memory is an integral part of a microprocessor system, and in this section, we will discuss how to interface a memory device with the microprocessor. The Memory Interfacing in 8085 is used to access memory quite frequently to read instruction codes and data stored in memory. This read/write operations are monitored […]

Features of Microprocessor 8257 DMA Controller

Features of Microprocessor 8257 DMA Controller: The Features of Microprocessor 8257 DMA Controller are follows, 1. It is a programmable; 4-channel, direct memory access controller. Each channel can be programmed individually. Therefore, we can interface 4 input/output devices with 8257. 2. Each channel includes a 16-bit DMA address register and a 14-bit counter. DMA address […]

8257 DMA Controller

8257 DMA Controller: In microprocessor based systems data transfer can be controlled by either software or hardware. Upto this point we have used program instructions to transfer data from I/O device to memory or from memory to I/O device. To transfer data by 8257 DMA Controller method microprocessor has to do following tasks : To […]

Input Output Transfer Techniques

Input Output Transfer Techniques: In Input Output Transfer Techniques, the system requires the transfer of data between external circuitry and the microprocessor. In this section, we will discuss different ways of I/O transfer. Program controlled I/O or Polling control . Interrupt program controlled I/O or interrupt driven I/O. Hardware controlled I/O. I/O controlled by Handshake […]

Features of 8085 Microprocessor

Features of 8085 Microprocessor: The Features of 8085 Microprocessor include : 1.It is an 8-bit microprocessor i.e. it can accept, process, or provide 8-bit data simultaneously. 2.It operates on a single +5V power supply connected at Vcc; power supply ground is connected to Vss. 3.It operates on clock cycle with 50% duty cycle. 4.It has […]

Types of LCD Displays

Types of LCD Displays: The Types of LCD Displays are one of the most fascinating material systems in nature, having properties of liquids as well as of a solid crystal. The terms liquid crystal refers to the fact that these compounds have a crystalline arrangement of molecules, yet they flow like a liquid. Liquid crystal […]

8279 Block Diagram

8279 Block Diagram: Fig. 14.84 shows the 8279 Block Diagram. It consists of four main sections CPU interface and control section Scan section 8279 Keyboard section Display section 1.CPU Interface and Control Section: This section consists of data buffers, I/O control, control and timing registers, and timing and control logic. Data Buffers The data buffers […]

8257 Pin Diagram

8257 Pin Diagram: Fig. 14.61 shows 8257 Pin Diagram. Data Bus (D0-D7) : These are bi-directional tri-state signals connected to the system data bus. When CPU is having control of system bus it can access contents of address register, status register, mode set register, and a terminal count register and it can also program, control […]

8255 Interfacing with 8086

8255 Interfacing with 8086: Fig. 14.17 shows the 8255 Interfacing with 8086 Microprocessor and Interfacing 8255 with 8085 Microprocessor in I/O mapped I/O technique. Here RD and WR signals are activated when IO/M signal is high, indicating I/O bus cycle. Reset out signal from 8085 is connected to the RESET signal of the 8255. Interfacing […]

Microcontroller 8031 and 8051

Microcontroller 8031 and 8051: 8051 Addressing Modes : The 8051 Addressing Modes architecture supports several distinct physical address spaces. On – chip program memory On – chip data memory External program memory External data memory On-chip special function registers The most of the instructions can operate with variables from these physical address spaces.. Now we […]