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8085 Articles
Page 6 of 36
ALE pin in 8085 Microprocessor
Intel 8085 is an 8-bit microprocessor which has 16 address line for 16-bit address of a memory location. 8 higher order address bits are transferred through 8 bit lines out of this 16 address line while remaining lower order 8 bits of the address are sent through another 8 lines multiplexed with the 8-bit data lines. ALE (Address Enable Latch) is the control signal which is nothing but a positive going pulse generated when a new operation is started by microprocessor. So when pulse goes high means ALE=1, it makes address bus enable and when ALE=0, means low pulse makes ...
Read MoreIO/M* PIN in 8085 Microprocessor
In Intel 8085 microprocessor I/O and memory operation are differentiated by IO/m` status signal.IO/M` stands for ‘input-output/memory`’. When IO/M` is logic 0, it means that the address sent out by the processor is for addressing a memory location. When IO/M` is logic 1, it means that the address sent out by the processor is for addressing an I/O port.Fig: Pin diagram of 8085Let us consider this following example and also the voltage level at IO/M* pin. If we consider instruction MVI E, ABH then it means that ABH will be moved or copied to the register E. And as a ...
Read MoreProgrammer's view of 8085 Microprocessor
Intel 8085 receives 8-bit information on AD7-0 from memory or in-port which resides inside the microprocessor via“register”. A register is a group of flip-flops, where each flip-flop can store a bit of information. To store 8 bitsof information, the size of a register in 8085 has to be 8 bitsThe advantages of a register over a memory location is the contents of a register can be accessed much faster by the microprocessor, compared with the contents of a memory location.However, the disadvantages of a register over a memory location are as follows.If there are too many registers, they occupy a lot ...
Read MoreAccumulator or Register A in 8085 Microprocessor
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 involving two operands, one operand has tobe in this register. And the result of the arithmetic operation will be stored or accumulated in this register. Similarly, in a logical operation involving two operands, one operand has to be in the accumulator. Also, some other operations, like complementing and decimal adjustment, ...
Read MoreRegisters of 8085 Microprocessor
It has eight addressable 8-bit registers: A, B, C, D, E, H, L, F, and two 16-bit registers PC and SP. These registers can be classified as −General Purpose RegistersTemporary Registers: a) Temporary data register b) W and Z registersSpecial Purpose Registers: a)Accumulator b) Flag registers c) Instruction registerSixteen-bit Registers: a) ProgramCounter (PC) b) Stack Pointer (SP)General Purpose RegistersRegisters B, C, D, E, H, and L are general purpose registers in 8085 Microprocessor. All these GPRS are 8-bits wide. They are less important than the accumulator. They are used to store data temporarily during the execution of the program. For ...
Read MoreAD7-0 pins in 8085 Microprocessor
The Intel 8085 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. When the 8085desires to receive 8-bit information, it receives it on these eight pins AD7, AD6, …, AD0. These eight pins are collectively called AD7-0. They are called basically “Address Data”. When the 8085 desires to send out 8-bit information, it sends it out on these same pins. these pins are bi-directional pins.The same lines are used for both receiving information and ...
Read MoreProgram memory structure of Intel 8051
We have already discussed that the 8051 microcontroller has the internal program memory. In this chip, there is EA pin. It indicates the External Access. So by using this pin, we can check whether the internal program memory is used or not. So when there is a low signal in this pin, the internal 4K bytes of program memory is not used, but in this situation, it can access only the ROM.When we are trying to access the external data memory, then the read RD or write WR will be the output from 8051. So for reading the data from ...
Read MoreData Memory Structure of Intel 8051
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 to increase the total amount of data memory. When we are trying to access the external data memory, then the read RD or write WR will be the output from 8051. The external data memory address can be either 8-bit or 16-bit wide. Generally, the one 8-bit address is used ...
Read More2's complement notation
This is one of the methods of representing signed integers in the computer. In this method, the most significant digit (MSD) takes on extra meaning.If the MSD is a 0, we can evaluate the number just as we would any normal unsigned integer.If the MSD is a 1, this indicates that the number is negative.The other bits indicate the magnitude (absolute value) of the number.If the number is negative, the other bits signify the 2'scomplement of the magnitude of the number.Thus a positive number has the same representation in SM, 1's complement, and 2's complement notations. Only negative numbers are represented ...
Read MoreProgrammer's view of 8051
Now let us see the internal registers, memory and other details from the Programmer’s point of view.There are these componentsEight registers(8-bit) R0 to R7Register A and B.These are also 8-bit registersPSW, Stack Pointer(SP), four ports (P0 to P3). These are also 8-bitDPTR register of 16-bit. This is divided into two 8-bit registers, these are DPH and DPLData RAM from location 08H to 7FHProgram memory from location 0000H to FFFFHProgram Counter (PC) of 16-bit
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