processor 8085 alp doubt

[vasanth kumar]

when I was trying to find answer for the following question, I got the answer 1022. please help me with your answers also.

find how many times the two JNZ are executed?

LXI H, 0503h
DCR L. : LOOP
JNZ LOOP
DCR H
JNZ LOOP
HLT
:roll:

 

[pjmelect]

The bottom JNZ is executed 80 times and the top JNZ is executed 240 times (3*80). I assume the LOOP labile is before the DCR L instruction not after it other wise the answer is infinite.

 

[FvM]

find how many times the two JNZ are executed?

Depends on what you understand as executed. There are 1022 jumps but the instructions are also executed several times without a jump.

 

[andre_luis]

You can download a JAVA application categorized as GNU General Public License version to perform this simulation :
Download website: https://sourceforge.net/projects/j8085sim/?source=pdlp

just out of curiosity, I run this code, and had to perform some adjusts at the one you gave above, but an error happens after simulation.
I´m not sure, but seems as value 0503h may be oversized to register magnitude, I guess.

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Code ASM - [expand]
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2
3
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LXI H, 1283 ; decimal conversion for 0503 HEX
DCR L
LOOP:
JNZ LOOP
DCR H 
JNZ LOOP
HLT ;

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+++

 

[FvM]

As already mentioned in post #2, the label must be placed before DCR L.

I´m not sure, but seems as value 0503h may be oversized to register magnitude, I guess.

Register pair HL is loaded with a 16-bit value.

 

[andre_luis]

Unfortunately, at downloaded application, could not find any box which could perform time accounting for the simulated program, just fixed according to post #2.

As already mentioned in post #2, the label must be placed before DCR L.
Register pair HL is loaded with a 16-bit value.

But, seems as instruction at line bellow performs a load at half of HL pair :

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Code ASM - [expand]
1
LXI H, 1283 ; decimal conversion for 0503 HEX

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+++

 

[FvM]

LXI H loads a 16-bit value. https://en.wikipedia.org/wiki/Intel_8080#16-bit_operations