The microcomputer system basically consists of three blocksThe microprocessorThe memories of microprocessor like EPROM and RAMThe I/O ports by which they are connected.The possible data transfers are indicated below.Between the memory and microprocessor data transfer occurs by using the LDA and STA instructions.Between microprocessor and I/O ports also data transfer occurs by the help of two instructions IN and OUT.Through DMA data transfer, data is transferred between the Input Output ports and the memory.Fig: The figure shows possible ways of data transfers in a microcomputer system.For performing the data transfer either between the microprocessor and memory or between I/O ports ... Read More

As per DIP package Intel 8257 DMA controller chip is a 40-pin programmable Integrated Circuit. The pin diagrams of physical and functional are indicated below. The DMA controller chip 8257 works in two modes namely −Slave Mode andMaster Mode.Likely the processor also works in two modes namely active mode and HOLD mode. The processor normally works in active mode where the processor works as the master of the computer system. The processor goes to the HOLD state only when DMA transfer is required and it gives control to the system bus.When the processor is programming 8257 it is in slave ... Read More

In the Central Nervous System, Human Brain is the main organ. It comprises of the cerebrum, the brain stem, and the cerebellum. It controls the vast majority of the body activities, processing, incorporating, and coordinating the data it gets from the sensory organs and deciding the instructions sent to the rest of the body. The mind is contained in and secured by the skull bones of our head.The human cerebrum is mainly made up of neurons, glial cells, and veins. Interneurons, pyramidal cells including Betz cells, motor neurons, and cerebellar Purkinje cells are the various types of neurons. Betz cells are ... Read More

In this program, we will see how to divide two 8-bit numbers using 8085 microprocessor.Problem StatementWrite 8085 Assembly language program to divide two 8-bit numbers and store the result at locations 8020H and 8021H.DiscussionThe 8085 has no division operation. To get the result of the division, we should use the repetitive subtraction method. By using this program, we will get the quotient and the remainder. 8020H will hold the quotient, and 8021H will hold the remainder.We are saving the data at location 8000H and 8001H. The result is storing at location 8050H and 8051H.InputThe Dividend: 0EHThe Divisor 04HThe Quotient will be ... Read More

In this program, we will see how to multiply two 8-bit numbers using 8085 microprocessor.Problem StatementWrite 8085 Assembly language program to multiply two 8-bit numbers stored in a memory location and store the 16-bit results into the memory.DiscussionThe 8085 has no multiplication operation. To get the result of multiplication, we should use the repetitive addition method. After multiplying two8-bit numbers it may generate 1-byte or 2-byte numbers, so we are using two registers to hold the result.We are saving the data at location 8000H and 8001H. The result is storing at location 8050H and 8051H.InputAddressData......8000DC8001AC......Flow DiagramProgramAddressHEX CodesLabelsMnemonicsCommentsF00021, 00, 80LXIH, 8000HLoad first ... Read More

In this program, we will see how to subtract two 8-bit numbers using 8085 microprocessor.Problem StatementWrite 8085 Assembly language program to subtract two 8-bit numbers and store the result at locations 8050H and 8051H.DiscussionIn 8085, the SUB instruction is used 2’s complemented method for subtraction. When the first operand is larger, the result will be positive. It will not enable the carry flag after completing the subtraction. When the result is negative, then the result will be in 2’s complemented form and carry flag will be enabled. We are using two numbers at location 8000H and 8001H. When the numbers are ... Read More

In this program, we will see how to add two 8-bit numbers using 8085 microprocessor.Problem StatementWrite 8085 Assembly language program to add two 8-bit numbers and store the result at locations 8050H and 8051H.DiscussionTo perform this task, we are using the ADD operation of 8085 Microprocessor. When the result of the addition is the 1-byte result, then the carry flag will not be enabled. When the result is exceeding the 1-byte range, then the carry flag will be 1We are using two numbers at location 8000H and 8001H. When the numbers are 6CH and 24H, then the result will be ... Read More

Now let us see a program of Intel 8085 Microprocessor. This program is mainly for finding a square of a number.Problem StatementWrite 8085 Assembly language program to find the square of a number using Look-Up Table. DiscussionIn this example, we are using Look-Up table to find the square of a number. The main limitation of this program is that it can find a square in range 0-F. When the input is above F, it will fail. We are storing the square result into the memory. When the number is greater than F, we are storing FFH into memory to indicate an ... Read More

Now let us see a program of Intel 8085 Microprocessor. This program will convert HEX to ASCII values.Problem StatementWrite 8085 Assembly language programs to convert Hexadecimal characters to ASCII values.DiscussionWe know that the ASCII of number 00H is 30H (48D), and ASCII of 09H is39H (57D). So all other numbers are in the range 30H to 39H. The ASCII value of 0AH is 41H (65D) and ASCII of 0FH is 46H (70D), so all other alphabets (B, C, D, E, F) are in the range 41H to 46H.Here we are providing hexadecimal digit at memory location 8000H, The ASCII equivalent ... Read More

Now let us see a program of Intel 8085 Microprocessor. This program will convert ASCII to HEXvalues.Problem StatementWrite 8085 Assembly language program to convert ASCII to Hexadecimal character values. DiscussionWe know that the ASCII of number 00H is 30H (48D), and ASCII of 09H is39H (57D). So all other numbers are in the range 30H to 39H. The ASCII value of 0AH is 41H (65D) and ASCII of 0FH is 46H (70D), so all other alphabets (B, C, D, E, F) are in the range 41H to 46H.Here the logic is simple. We are checking whether the ASCII value is less ... Read More