Input / Output (I/O) Interfacing

I/O interfacing

Input and output interfaces provide a method of transferring information between internal storage (M.P.) and external I/O device. Peripherals connected to a computer need special communication links for interfacing them with CPU. The purpose of the communication link is to resolve the difference that exists between the processor and each peripheral.

The major differencing are:

Branching Group Instruction

Branching Group Instruction The branching instruction instructs the processor to go to a different memory location and the microprocessor continues excluding machine code from the new location. The branching instructions are the most powerful instructions because they allow the microprocessor to change the sequence of program either unconditionally or under certain test condition. The branching instructions are divided into following 3 groups: a. JUMP instruction b. CALL and RET instruction c. RESTART instruction The jump instruction specifies the memory location explicitly. They are 3 bytes instruction. Jump instruction categories into unconditional and conditional. 1. Unconditional Jump: 8085 includes unconditional JUMP instruction loop without depending any types of conditions. JMP 16-bit address e.g. JMP 4000H Memory location can also be specified with a label or name 2. Conditional Jump: The conditional JUMP instructions allow the microprocessor to make decision based on certain condition indicated by the flag. After logical and arithmetic operations flag are set or reset to reflect condition. The four flags namely CY, P, Z and S are used by JUMP instructions.

Addressing Mode: Logical Group

Logical Group:  A microprocessor is basically a programmable logic chip which can perform all the logic function of the hardwired logic through it instruction set. The 8085 instruction sets the 8085 instruction set includes such logic functions as AND, OR and NOT. The following features hold true for all logic instruction.

Addressing Mode: Arithmetic Group Instruction

Arithmetic Group Instruction:     The 8085 microprocessor performs various arithmetic operations such as addition, subtraction, increment and decrement. These arithmetic operations have the following mnemonics.

Data transfer group

Data transfer group: These instruction which are used to transfer a data from one register to another or register to memory or vice versa. E.g. MOV, MVI, LDA etc.

Instruction Sets and Qualification

It is a command given to a computer to perform specific operation on given data. The entire group of instruction called the instruction set. In 8085, instruction set can be classified into 5 different groups.

i.>                          Data transfer group

ii.>                        Arithmetic group

iii.>                     Logical group

iv.>                      Branching group

v.>                        Miscellaneous

Instruction Sets and Qualification

It is a command given to a computer to perform specific operation on given data. The entire group of instruction called the instruction set. In 8085, instruction set can be classified into 5 different groups.

i.>                          Data transfer group

ii.>                        Arithmetic group

iii.>                     Logical group

iv.>                      Branching group

v.>                        Miscellaneous