Hello forums, I started playing with a coding the 8051 after a long search for an assembly language to learn and it seemed like the way coolest one. I looked around a bit for how to do this but I probably just couldn't word it correctly; what I'm trying to do is fill memory locations 0x0200-0x05ff with a certain value, doesn't matter what it is. If i had to just do something like fill locations 0x200-0x2ff it would be easy as I could just use:
mov r0, # 100h mov dptr, # 200h a: mov a, #27 mov @dptr, a inc dptr djnz r0, a
but what is the best way to do it for more than 256 bytes?
Answers on a postcard please.
Setting an overflow bit would be something only the microcontroller running a program can do.
Having an assembler source file assigning a value larger than 8 bits would not manage to let the microcontroller see any overflow - the assembler wouldn't manage to find any space for storing that overflow bit in the assing instruction. So any truncate has to happen in the assembler, before a machine code instruction is generated.
Having an assembler source file assigning a value larger than 8 bits would not manage to let the microcontroller see any overflow
Well, the designer of an 8051 assembler might, in a particularly nasty mood, decide to actually respect the expressed wish of such assembly program writers and translate
mov r0, #100h
as if the source had been
mov r0, #0 setb c
;-P
And a nicer assembler developer would emit: "Warning: Numeric constant/expression out of range for target register."
Probably best if you avoid future attempts at humour. Maybe you have strengths in another field.