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stores next instructions

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โˆ™ 2010-09-25 04:46:00
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Q: How does the 8085 microprocessor instruction register work?
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Difference between register variable and automatic variables?

Register variables are stored in register of microprocessor/micro-controller. The read/write access to register variable is the fastest because CPU never need any memory BUS operation to access these variable. Auto variable are stored in stack thus access are much slower. Auto variable can be converted to register by using register keyword before it. It has platform specific limitation. Register variable will work only if free registers are available to hold the variable for a function scope. In case of Microprocessor or microcontrollers having very less number of general purpose registers will never take register variable even if we declare it as register.


Difference between direct and indirect instruction?

Direct instruction is being taught face to face in person. Indirect instruction would be things like online classes and at home work.


What is the difference between register and resister in elecronics?

A resistor reduces the flow of current between two terminals and thus reduces voltage. this is achieved through electrical resistance. All electrical conductors are resisters, some more resistant than others. The less resistance offered by a conductor, the easier it is for electricity to flow, thus the higher the current. Thus resisters allow circuit designers to control the flow of electricity. A register is a small unit of storage used by a digital processor. Computers typically have a relatively large array of working memory, however all the actual processing is done via a small set of registers. Registers work in much the same way as main memory, typically using a capacitor and transistor pair to denote each bit, however registers are significantly faster. Some registers are used for housekeeping purposes such as to keep track of the next instruction and for marking the top of the program stack, while other are used to provide input and output for the current instruction. In order for an instruction to process a value that value must first be moved to a register, typically one of the accumulator registers. If the instruction requires another operand, it must be moved to another register, typically a user register. After processing, the accumulator's value is moved back to main memory, either by the instruction itself or by a subsequent instruction.


What is the function of the instruction counter?

There is no such thing as an instruction counter. You are either referring to the instruction register (IR) or the program counter (PC), The PC is more commonly known as the instruction pointer (IP). The IR and IP work together. The IR fetches the instruction currently pointed to by the IP which is then incremented to refer to the next instruction. The IR is then decoded and executed and the cycle repeats ad infinitum (known as the fetch-decode-execute cycle). However, if the fetched instruction is a control transfer instruction (such as JMP), its execution will cause the IP to refer to another address which, in turn, causes execution to "branch" to a new section of code on the next fetch-decode-execute cycle. Note that a low-level JMP is equivalent to a goto statement in high-level code, however code can also branch through high-level if and switch statements as well as structured loops such as for, while and do-while statements.


What application instruction that make the computer hardware work?

The CPU does all the actual work and there can easily be a hundred or more separate instructions that a modern CPU understands, each of which does a very minute job, whether it is to move a value into a register or into memory, or to compare register values, or to perform simple arithmetic upon them, and so on. Common interfaces provided by the BIOS allow the CPU to interact with the basic hardware components in order to load an operating system, while the operating system itself provides more specific device control via driver software.

Related questions

Why zero flag is not set in INX instruction of microprocessor 8085?

Because that is the way Intel designed the INX instruction of the 8085. The 8080 is also the same. INX increments (and DCX decrements) the 16 bit register pairs or BC, DE or HL, depending on what register pair you specify in the INX (or DCX) instruction. To check is the value is 0 after an INX (or DCX) instruction, you need to OR the values of the register pair into the A register. For example..... INX H ;increment HL register pair MOV A,H ; move H register into the accumulator ORA L ; Logical OR it with the L register JZ ADDR ; If 0 then jump to ADDR


How 8085 microprocessor got its name?

the previous CPU of Intel is 8080A. 8085 is the first CPU to work in 5volts. hence the name 8085 (8080+5)


What relation is among microprocessor motherboard and personal computer?

The both, Microprocessor and Motherboard are the major and basic components of a personal computer. The microprocessor plugged in the motherboard and work as a brain of a personal computer after any instruction or a command by the user.


What is the general purpose register in 8085 microprocessor?

In 8085 general purpose registers are used to hold data like any other registers. In 8085 there are six types of special registers called general purpose registers. The general purpose registers in 8085 are B, C, D, E, H and L. Each register can hold 8 bit data. Apart from above functions these registers can also be used to work in pairs to hold 16 bit data. They can work in pairs such as B-C, D-E, H-L to store 16 bit data. The H-L pair work as a memory pointer. A memory pointer holds the address of a particular memory location. They can store 16 bit address as they work in pairs.


Draw a schemetic to demultiplex bus ad0-ad7 using any octal latch in 8085 microprocessor?

The 8085 microprocessor is used IC 74LS373 to latch the address of 8085. Basically latch is consists of 8 flip flops. Generally we used D-flip flops (Delay).The clock of these flip flops are connected together and available as a output pin called enable.Working : The address will appear on AD0 AD7 lines. The ALE will go high and forcingEnable = 1. This will make latch enable and ready to work. Before address disappears ALE = 0. This will make latch disable. AD0 - AD7 will now be used as data bus.Hence, AD0 - AD7 (low order) address bus of the 8085 microprocessor is multiplexed (time-shared) with the data bus. The buses need to be demultiplexed.


Difference between register variable and automatic variables?

Register variables are stored in register of microprocessor/micro-controller. The read/write access to register variable is the fastest because CPU never need any memory BUS operation to access these variable. Auto variable are stored in stack thus access are much slower. Auto variable can be converted to register by using register keyword before it. It has platform specific limitation. Register variable will work only if free registers are available to hold the variable for a function scope. In case of Microprocessor or microcontrollers having very less number of general purpose registers will never take register variable even if we declare it as register.


How does the Fetch Decode Execute work?

The program counter in the processor holds the address of the next instruction needed from main memory. The program counter copies its contents into the memory address register. The memory address register then sends the address along the address bus to main memory and the contents of the memory location specified by the address are sent along the data bus to the memory buffer register. The contents of the memory buffer register are then copied to the current instruction register where they are decoded and executed.


How does fetch decode cycle work?

The program counter in the processor holds the address of the next instruction needed from main memory. The program counter copies its contents into the memory address register. The memory address register then sends the address along the address bus to main memory and the contents of the memory location specified by the address are sent along the data bus to the memory buffer register. The contents of the memory buffer register are then copied to the current instruction register where they are decoded and executed.


Can microprocessor work in freezers?

Yes they can.


How does PUSH instruction work in 8086?

I am not sure about 8086, but I can tell you the whole procedure in 8085. PUSH instruction always pushes two bytes of data i.e. total 16 bits. Example: Assume that Stack is already initialized and SP is at 2008 address location. Then PUSH B instruction will have following steps: 1) The stack pointer (SP) will be pointing to the uppermost position of the stack (actually stack works in opposite order in terms of Addresses. e.g. if SP is now at address 2008, then PUSH instruction will store the contents on 2007 & 2006). 2) The contents of register B & C will be saved on to the stack such that contents of register B will be at 2007 & that of C will be at 2006 address location. 3) The SP is now modified to 2006.


How does the fetch-decode-execute cycle work?

The program counter in the processor holds the address of the next instruction needed from main memory. The program counter copies its contents into the memory address register. The memory address register then sends the address along the address bus to main memory and the contents of the memory location specified by the address are sent along the data bus to the memory buffer register. The contents of the memory buffer register are then copied to the current instruction register where they are decoded and executed.


How does fetch decode execute cycle work?

The program counter in the processor holds the address of the next instruction needed from main memory. The program counter copies its contents into the memory address register. The memory address register then sends the address along the address bus to main memory and the contents of the memory location specified by the address are sent along the data bus to the memory buffer register. The contents of the memory buffer register are then copied to the current instruction register where they are decoded and executed.

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