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Questions tagged [8085]

The Intel 8085 is an 8-bit CPU from the 1970's. Use this tag for queries regarding assembly code written for 8085.

The Intel 8085 processor was introduced in the late 1970's as an improved version of the then popular 8080 CPU.

It was soon succeed by the 16-bit 8086, the first x86 processor.

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Assembler for old 8085 program with directives like .page or .=0000h

I'm trying to replace an old EPROM that was flashed with a program written for 8085 processor. Although I have the assembler listing, it does not seem to work in any 8085 assemblers I was able to find - mostly because of assembler directives that…
The
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Terms used for addressing modes. [intel 8085]

In the documentation of a processor I am working on it says : Operand addressing modes available are implied, register, immediate, direct and register indirect (using the BC, DE and HL register pairs as 16-bit pointers to memory). Can…
Johnny Riley
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auxiliary carry and carry flags in 8085

It is said that the subtraction is performed in 2's complement in 8085 and so the flags must be set according to the operation. However,in the figure shown, i am unable to figure out the reason behind auxiliary carry flag being set to '0' and the…
nishant nalin
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Status of program counter during hlt

In the Intel 8085 microprocessor, precisely at what point (t state) does the program counter get updated? Is it just after t1 (i.e., just when the current address in the PC is placed on the address bus) or at t3, when the instruction fetch is being…
Yashwanth Reddy
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8085 Instruction: JMP - Number of machine cycles when condition is not satisfied?

The machine code for the JMP instruction comprises of: opcode - 11CCC010 (where CCC is the state of the flag bit used to set the condition) 8 bits and address for the jump - let's say a 16 bit address. First there is a fetch operation of the opcode…
aste123
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Why does 8085 start from 00000 while 8086 from FFFF0?

I am unable to understand the different starting addresses of Physical Address generated by CS:IP in 8085-86. Is this because of Stack? I think the concept of Stack was present before 8085. Please help out. Thanks.
user379888
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How do I need to change assembly code that it is going to work correctly?

I wrote a code in assembly language for the 8085 microprocessor. The code should change uppercase letters to lowercase. Maybe can you help me of finding the mistakes which I made in the code. All the text should be written in ASCII. And the first…
Liuzili
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How can I run assembly code by bypassing the operating system?

First of all, I don't know about modern CPUs and operating systems. For this reason, I will explain my explanation over the intel 8085 processor. And of course, I would like you to imagine that there is an operating system that can run on the intel…
suiciyom
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Assembly problem adding unknown value into A

Hello i have the following program in assembly language for an 8085 microproccesor and i need to find the final value of B. Even tho the exercise is quite simple making the hexadecimal numbers into binary and then doing the logical thingies I am…
Steve
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Current state of Stack Pointer in 8085

In Intel 8085 microprocessor, is there any way or instruction exist for find out, to where Stack Pointer currently points to?.
Mannar Amuthan
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8085 program to filter out positive numbers from a memory location

So i need to filter out the positive numbers and display the sum if it is less than FFH, if not display FFH. i typed the code in the simulator and use #DB to store the numbers in a particular memory location. but when i run it step by step the…
mahibonu10
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How to converting 8085 code to z80 assembly

I have 8085 assembly code for dividing 2 data 8 bit : MVI C,FFH LXI H,1900H MOV A,M (A=08) INX H MOV B,M (B=3) REPEAT: INR C SUB B JNC REPEAT ADD B INX H …
谢RenS
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Clock cycle and memory usage of an 8085 assembler program

I have this small little program written in assembly that squares a number. Org 2010h Db 0ah Org 2013h Db 00h Org 1000h mvi a, 00h lxi hl, 2010h mov b, m mov c, m CYCLE: add b dcr c jnz CYCLE …
franklin
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ANI F0 does not work as expected in 8085 simulator

I run the following program in the 8085 simulator and when it hits address 0016 ANI F0 does not work properly. Is it a bug or I am missing something? MVI L,17 MVI E,99 MOV A,L ANI 0F MOV M,A …
themhz
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Largest number in an array - 8085 microprocessor

I want to store the address of the largest number in HL but I don't really know how to do it This is what i've done so far 0000 LXI H,3000H ;Load H-L pair with address 3000H 0001 0002 0003 MOV E,M ;Move counter from memory to…
user9090540
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