Saturday, September 12, 2009

Transfer contents to overlapping memory blocks (8085)

Statement: Write assembly language program with proper comments for the following:
A block of data consisting of 256 bytes is stored in memory starting at 3000H. This block is to be shifted (relocated) in memory from 3050H onwards. Do not shift the block or part of the block anywhere else in the memory
Source Program:
Two blocks (3000 - 30FF and 3050 - 314F) are overlapping. Therefore it is necessary to transfer last byte first and first byte last.
MVI C, FFH : Initialize counter
LX I H, 30FFH : Initialize source memory pointer 3l4FH
LXI D, 314FH : Initialize destination memory pointer
BACK: MOV A, M : Get byte from source memory block
STAX D : Store byte in the destination memory block
DCX H : Decrement source memory pointer
DCX : Decrement destination memory pointer
DCR C : Decrement counter
JNZ BACK : If counter 0 repeat
HLT : Stop execution

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