Search This Blog

The 8085 Microprocessor

Previous Years Questions Papers

Get link
Facebook
X
Pinterest
Email
Other Apps

July 17, 2019

Get link
Facebook
X
Pinterest
Email
Other Apps

Comments

Followers

Generation of Control Signals of 8085

August 30, 2018

Generation of Control Signals In any system, there are different modes of operations. Likewise, in some situation we are interested to read data in microprocessor, in other we are interested to write data on some location from microprocessor. Whenever, we are dealing with different peripherals using 8085 microprocessor there are two modes of operations. One is to read data from any of the memory device or input device. Second is to write data on some location, this location can be any of the output device location or any of the memory location. To deal with these modes 8085 microprocessor architecture gives three different control signals. Namely IO/ M , RD and WR . The IO/ M is an output pin of the 8085 microprocessor which serves dual purpose, the high going pulse on this pin indicates the I/O type of operation. We can state that, at this time 8085 is working with the input or output devices. The low going pulse on this pin indicates the memory oper...

Demultiplexing Address/Data Bus AD7- AD0

August 13, 2018

Pin 30 of 8085 is the ALE pin which stands for ‘Address Latch Enable’. ALE signal is used to demultiplex the lower order address bus (AD0 – AD7). Pins 12 to 19 of 8085 are AD0 – AD7 which is the multiplexed address-data bus. Multiplexing is done to reduce the number of pins of 8085. Lower byte of address (A0 – A7) are available from AD0 – AD7 (pins 12 to 19) during T1 of machine cycle. But the lower byte of address (A0 – A7), along with the upper byte A8 – A15 (pins 21 to 28) must be available during T2 and rest of the machine cycle to access memory location or I/O ports. Now ALE signal goes high at the beginning of T1 of each machine cycle and goes low at the end of T1 and remains low during the rest of the machine cycle. This high to low transition of ALE signal at the end of T1 is used to latch the lower order address byte (A0 – A7) by the latch IC 74LS373, so that the lower byte A0 – A7 is continued to be available till the end of the machine cycle. The situation is explained in...

Assemblers & Assembler Directives

July 25, 2019

To assemble a program automatically the assembler needs information in the form of assembler directives that controls the assembly or Assembler directives are the directions to the assembler which indicate how an operand or section of the program is to be processed. These are also called pseudo operations which are not executable by the microprocessor. For example, the assembler must be told at what address to start assembling the program. These assembler directives are command placed in the program by the designer that provides information to the assembler. They do not become part of the final program as they are not the part of the instruction set of the microprocessor nor did they translate into executable code. Therefore, they are also known as pseudo-instruction on false instructions. Each assembler has its own unique pseudo instructions or assembler directives. These instructions differ from assembler to assembler but most of the assembler contains an equivalent set of pseu...

Previous Years Questions Papers

Comments

Post a Comment