Unknown 8085 opcodes

Sean Conner spc at conman.org
Thu Jan 12 15:30:41 CST 2017


It was thus said that the Great Fred Cisin once stated:
> >>		jsr	puts
> >>		fcc	'Hello, world!',13,0
> >>		clra
> or the classic:
>    JMP START1
>    DATA2:	DB . . .
>         	DB . . .
>    START1: MOV DX, OFFSET DATA2 
> Which was heavily used because
>    MOV DX, OFFSET DATA3
>    . . .
>    DATA3: DB . . .
> would pose "forward reference" or "undefined symbol" problems for some 
> assemblers.
> 
> Even for manual assembly, or 'A' mode of DEBUG.COM, it was handy to 
> already know the address of the data before you wrote the steps to access 
> it.
> 
> On Thu, 12 Jan 2017, Mouse wrote:
> >Mine can't do that automatically, but it can with a little human
> >assist; the human would need to tell it that the memory after the jsr
> >is a NUL-terminated string, but that's all it would need to be told.
> 
> Not all strings are null-terminated.  In CP/M, and MS-DOS INT21h Fn9, the 
> terminating character is '$' !
> "If you are ever choosing a termination marker, choose something that 
> could NEVER occur in normal data!"
> Also, strings may, instead of a terminating character, be specified with a 
> length, or with a start and end address.

  I've seen the high bit set on the last character, again mostly in the
8-bit world.

  -spc



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