In this module we have explained the complete interface of four numbers segmented into seven parts having the Light Emitting Diode which uses a serial data transfer scheme. The portion which is displayed of the interface has 4 LEDS comprises of 7-segments LEDs as we can see from the physical layout of the interface. The connection to the interface is done by the ALS-8085 kit which uses a flat table of 26 crores. We connect the connector C1 to the interface to the Input Output connector P3 on the ALS kit. There is a power supply of of +5 V ... Read More

In mode 0 or mode 1, a port works as an input port or an output port. It is dependent if an input device or an output device gets connected to the port. Moreover, this, mode 2 is often called as bi-directional handshake Input Output. It is beneficial for us when the microprocessor receives information, and sometimes sends information to the Input Output device which is connected to 8255. An example to be cited as for the communication process with a floppy disk controller card. Since mode 2 is bi-directional handshake Input Output, it needs more number of handshake lines ... Read More

 An output device which is very common is, especially in the kit of 8085 microprocessor and it is the Light Emitting Diode consisting of seven segments. Moreover, we have eight segments in a LED display consisting of 7 segments which includes ‘.’, consisting of character 8 and having a decimal point just next to it. We denote the segments as ‘a, b, c, d, e, f, g, and dp’ where dp signifies ‘.’ which is the decimal point. Moreover, these are LEDs or together a series of Light Emitting Diodes. We have shown the internal circuit comprising of a display ... Read More

We call mode 1 as the strobed Input Output or handshake Input Output. We use this mode when the data is supplied by the input device to the microprocessor at irregular interval of time. A port which is functioned to program in mode uses three handshake signals. These handshake signals are provided by Port C. Only port A and B works in mode 1. The pins PC2, PC1, and PC0 provides handshake signals for port B when we configure it for Input port or Output port. Moreover, the pins PC7, PC6, and PC3 provides handshake signals for port A. The ... Read More

We interface the I/O device in a very segmented manner and is carried systematically. In the interfacing of seven segment display to 8085 microcontroller it is found that An output device which is very common is, especially in the kit of 8085 microprocessor and it is the Light Emitting Diode consisting of seven segments. Moreover, we have eight segments in a LED display consisting of 7 segments which includes ‘.’, consisting of character 8 and having a decimal point just next to it. We denote the segments as ‘a, b, c, d, e, f, g, and dp’ where dp signifies ... Read More

We write an 8085 assembly language program for the addition of 4 hex digits of a 16-bit number whose input is given from the keyboard and the result is displayed in the data field.FILE NAME ADDHEX.ASM ORG C000H CURDT: EQU FFF9H UPDDT: EQU 06D3H GTHEX: EQU 052FH HXDSP: EQU 05A1H OBUFF: EQU FFFAH MVI A, 0EH SIM EI ; Unmask RST5.5 and enable interrupts MVI B, 00 CALL GTHEX ; Input a 4 digit number and display in address field CALL HXDSP ; Store the 4 hex digits in 4 locations starting from OBUFF LXI H, OBUUF MOV A, M ... Read More

We write an 8085 assembly language program of two input using two 2-digit hexadecimal numbers from the keyboard and then we add and the output results in the address field.FILE NAME ADD2NUM.ASM ORG C000H CURAD: EQU FFF7H UPDAD: EQU 06BCH CLEAR: EQU 044AH GTHEX: EQU 052FH MVI A, 0EH SIM EI ; Unmask RST5.5 and enable interrupts MVI B, 01 CALL GTHEX ; Input a 2 digit number and display in data field MOV A, E STA C100H ; Store the 2-digit hex number in C100H MVI B, 01 CALL GTHEX ; Input a 2 digit number and display in ... Read More

We write a program in 8085 assembly language for implementing a decimal down counter (from 99 to 00). The program must be working in the following conditions.We load the accumulator with 99.Displaying the count value in the accumulator which is present in the accumulator. RST5.5 is in unmasked condition and the interrupt system gets enabled.The program is as follows:FILE NAME DOWNCNTR.ASM ORG C000H CURDT: EQU FFF9H UPDDT: EQU 06D3H RDKBD: EQU 0634H MVI A, 99H ; Initialize A with 99. REP: STA CURDT ; Store A value in CURDT. CALL UPDDT ; Display contents of CURDT in data field. MVI ... Read More

In 8255, there are two types of command words or control word are available. And they are −Mode definition control word andPort C bit set/reset control word.Both these are written to the control port only. From the point of view of the microprocessor there is a single 8-bit control port, which is selected when CS* = 0, WR* = 0, A1 = 1 and A0 = 1. But if we consider the architecture of 8255, internally there are two control ports, one for mode definition control and another for Port C bit set/reset control. The contents of the control port ... Read More

We write an 8085 assembly language program for finding the square of a single digit (0 to 9) using a look-up table for displaying a number and its square in the address field.FILE NAME MYSQR.ASM ORG C100H X: DB 00H, 01H, 04H, 09H, 16H, 25H, 36H, 49H, 64H, 81H ORG C000H CURAD: EQU FFF7H UPDAD: EQU 06BCH IBUFF: EQU FFFFH MVI A, 0EH ; Load A with 0000 1110B SIM ; Unmask RST5.5 i.e. enable keyboard interrupt. ; The next 4 instructions check if a key is pressed. If a key is ; pressed, ... Read More