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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