Found 558 Articles for Microprocessor

Here we will see how to change the state of LEDs with the input switches using 8085.Problem StatementAccording to the ON/OFF states of input switches connected at port A change the states of output LEDs to ON/OFF states connected to port B.DiscussionTo solve this problem, we have to use the IN and OUT instructions. The IN instruction is used to take the input from the input port to the accumulator, and OUT instruction is used to send output from Accumulator to the output port. Here 8255 chip is used. In the port A of this chip is connected to the ... Read More

Here we will see how to interface PORT IC with 8085.Problem StatementON/OFF desired output LEDs connected at the output port B.DiscussionHere we will see how to On/Off LEDs at port B. We are using 8255 IC for ports. The J1 and J2 connectors to connect the 8085 and 8255. The connector pin descriptions are given below. For controlling pin, we have to set the control word, that will be used in the program.Pin no. on J1/J28255 PinFunction113PC4212PC5316PC2417PC3514PC0615PC1724PB6825PB7922PB41023PB51120PB21221PB31318PB01419PB11538PA61637PA71740PA41839PA5192PA2201PA3214PA0223PA12311PC62410PC72526+5V267GND  Group A and B will operate in mode 0.Using port A as input port and port B as output port. The operation mode of ... Read More

Here we will see how to implement mathematical function using 8085.Problem StatementWrite a program to implement the following function (a*b) + (c*d) and store the result in memory locations 8204 and 8205. Perform multiplication by using a subroutine. Here a, b, c and d numbers are stored at memory locations 8200H, 8201H, 8202H and 8203 respectively.DiscussionMultiplication instruction is not present in the 8085. So we have to use subroutine to perform multiplication. In this subroutine, it takes number from memory pointed by HL pair, and return result into DE register pair. After multiplying two parts, the intermediate results are stored, ... Read More

Here we will see how to add even parity to 7-bit ASCII string using 8085.Problem StatementWrite a program to add even parity to a string of 7 bit ASCII characters. The length of the string is in memory location 8040 H and the string itself begins at memory location 8041 H. Place even parity in the most significant bit of each character.Discussion8085 has parity flat. that flag will be used to check and assign parity with each ASCII character. At first we will clear the most significant bit by masking the number with 7FH. Then use OR instruction, as this ... Read More

Here we will see how to add ten packed BCD numbers using 8085.Problem StatementA set of ten packed BCD numbers is stored in the memory location starting from 8040H to 8049H.Write a program with a subroutine to add these numbers in BCD. If a carry is generated save it to register B, and adjust it to BCD. The final sum will be less than 9999BCD. Store the sum at locations 8060H and 8061H.Write a second subroutine to unpack the BCD sum stored in registers A and B, and store them in the OutputBuffer memory starting at 8062H. The most significant ... Read More

Here we will see how to find the bit differences of two binary patterns using 8085.Problem StatementTwo binary patterns are stored in locations 8030H and 8031H. Load them in registers A and B. Find out the bit positions where bits are differing and put these location numbers at locations starting from 8050H on words. (Bits are differing at those locations where 0 in A and 1 in B)DiscussionTo solve this problem, we are taking the numbers into A and B. Then initialize the C as counter with 08H, and the register L will keep tract the bit position, where A ... Read More

The 8259 is known as the Programmable Interrupt Controller (PIC) microprocessor. In 8085 and 8086 there are five hardware interrupts and two hardware interrupts respectively. Bu adding 8259, we can increase the interrupt handling capability. This chip combines the multi-interrupt input source to single interrupt output. This provides 8-interrupts from IR0 to IR7. Let us see some features of this microprocessor.This chip is designed for 8085 and 8086.It can be programmed either in edge triggered, or in level triggered modeWe can mask individual bits of Interrupt Request Register.By cascading 8259 chips, we can increase interrupts up to 64 interrupt linesClock ... Read More

Here we will see the control words and the operation modes of the 8254 programmable interval timer chip.Before discussing its operating modes and control word properties, we should know about some important facts of this chip.When the chip is powering up, the state is undefined. The mode, count value, and outputs are undefined in that time.Each counter must be programmed before it is used. We do not need to program some unused counters.Counters are programmed by writing the control words and then one initial count.The structure of the counter is like this -76543210SC1SC0RW1RW2M2M1M0BCD/Binary We can select the counter by the SC1 ... Read More

Here we will see how to find 2’s complement with carry.Problem StatementWrite 8085 Assembly language program to find 2’s complement of a number stored in F100 with the carry, and store at F150 and F151.DiscussionIn 8085, there is CMA instruction to complement a number. Then we can add 01 with it to make it 2’s complement. While adding 01 with it, the carry may generate. We will store it to F151, and the actual complemented value will be at F150.InputAddressData……F10008…… Flow Diagram ProgramAddressHEX CodesLabelsMnemonicsCommentsF0003A, 00, F1 LDA F100Hget number from memory to AF0032F CMAget 1's complementF004C6, 01 ADI 01Increase it by 1F0066F MOV L, AStore A ... Read More

Here we will see how to add two 8-bit numbers without carry in 8085.Problem StatementWrite 8085 Assembly language program to perform 8-bit addition without carry. The numbers are stored at F100, and F101. Result will be stored at F102.DiscussionIn 8085, there is ADD instruction to add two numbers. We will set the HL pair to point the numbers, then load accumulator with the number. Then add with ADD M operation which can add items from memory pointed by HL pair and accumulator.InputAddressData……F100CEF10121…… Flow Diagram ProgramAddressHEX CodesLabelsMnemonicsCommentsF00021, 01, F1 LXI H, F100HPoint to get the numbersF0037E MOV A, MLoad first number to AF00423 INX HPoint to ... Read More