In 8085 Instruction set, there are two instructions in 8085 for communication with I/O ports. They are the IN and OUT instructions. The IN or OUT instruction mnemonics should be followed by an 8-bit port address. Thus we can have 28 = 256 input ports and 256 output ports are ... Read More

In 8085 Instruction set, IN is a mnemonic that stands for INput the Byte from input port’s content to the accumulator. Input port’s 8-bit address is indicated in the instructions as a8. It occupies 2 Bytes in the memory. First Byte specifies the opcode, and the next Byte provides the ... Read More

In this section, we will see the different types of instructions of Motorola M6800 microprocessor. There are 72 different types of instructions and 197 different opcodes. So there are 51 1-Byte instruction, 103 2-Byte instruction and 43 3-Byte instruction.As we know that the Intel 8085 has 246 opcodes, though 6800 ... Read More

In Motorola M6800, there are two hardware interrupt pins. These pins are NMI and. IRQ  These pins are active low input pins. The first one is non-maskable and the second one is maskable and lower priority interrupt. When the IM flag is 1, or CCR register is set, the interrupt ... Read More

Register A is an 8-bit register used in 8085 to perform arithmetic, logical, I/O & LOAD/STORE operations. Register A is quite often called as an Accumulator. An accumulator is a register for short-term, intermediate storage of arithmetic and logic data in a computer's CPU (Central Processing Unit).In an arithmetic operation ... Read More

The 8051 Microcontroller is designed by Intel in 1981. 8051 is 40 pin DIP IC. This is an 8-bit microcontroller.It is a very famous Microcontroller of Intel family. As we know Microprocessor like 8085, Z-80 or M6800 contains the ALU, control unit and some registers, but there were no internal ... Read More

The Intel 8085 ("eighty-eighty-five") is an 8-bit microprocessor produced by Intel and introduced in 1976. It is a software-binary compatible with the more-famous Intel 8080 with only two minor instructions added to support its added interrupt and serial input/output features. Intel 8085 can read or write 8 bits at a ... Read More

The 8051 has 128 bytes of On-Chip RAM. So for accessing that RAM area, the address space is 00H to 7FH. When we need more data memory, we can use external RAM. The address space of external RAM is 0000H to FFFFH.The external and internal data memory can be added ... Read More

To represent fractions may be necessary quite often inside the computer. For example, it may be needed to represent inside a computer a value like +0.610 or -0.610. To represent signed fractions, it is necessary to assume the binary point just after the MSB in the bit sequence. Such numbers ... Read More

The instructions of 8051 Microcontroller can be classified into five different groups. These groups are like belowData Transfer GroupArithmetic GroupLogical GroupProgram Branch GroupBit Processing GroupThis Bit-Processing group is also known as Boolean Variable Manipulation.Like 8085, some instruction has two operands. The first operand is the Destination, and the second operator ... Read More