Hi Fernando,

As people have pointed out, "dt" is part of the "directive language" that is
part of MPASM (and you can see in MPLAB -> "Help" -> "MPASM").

There are also "psuedo-assembler" instructions that I avoid largely because
I don't find it that much more difficult to write out the instructions (and
with 35 instructions and just knowing the basic Status Register flags, I
find that having to learn *more* instructions is more trouble than it's
worth).  These instructions include things like "BZ" which is Branch on Zero
Flag Set and is the equivalent of "btfsc STATUS, Z"/"goto {Label}".

I have been steering beginners, when I've been asked, away from using these
psuedo-assembler instructions because while they do make programming the PIC
easier, they make understanding the bit operations less intuitive.  I've
seen beginner's struggle with code like:

  mov    flag, w                ;  Get the Flags Register
  andlw  0x010                  ;  Test Bit 4
  BNZ    Label                  ;   and if it's set, Jump to Label

When:

  btfsc  flag, 4                ;  Test Bit 4
   goto  Label                  ;   and if it's set, Jumpt to Label

Will do the same thing in half the instructions and not affect the "w"
register or flags.

I avoid the Parallax set of instructions and warn beginners to stay away
even if they are familiar with 8051 operations.  I avoid it because
registers and Status register flags can get changed inadvertently without
the user neccessarily knowing it.

On these points, what do other people think?  When I see a snippet using the
"psuedo-assembler" or PAX assembler, for the most part I can figure out what
the instructions are doing, but I don't find them more efficient to use for
coding with at all.

myke

>Hi everyone,
>
>I've seen in Myke's book the use of pseudo-asm to abbreviate code in some
>situations (e.g. "dt" to implement lookup tables).  I've searched all over
>Microchip's literature and the web for more of these "short cuts" and haven't
>found a thing.  Does anybody know where the literature that describes these
>pseudo-ops can be found?  Are there many other such commands that also
>abbreviate code like dt?  Thanks.
>
>Fernando
>
>

"If people don't know what you're doing, they don't know what you're doing
wrong." - Sir Humphrey Appleby K.C.B