Lembit,

You can access to the RAM by its address:

to read the register:
movf  0x2C,w

to store to the register:
movwf   0x2C

You can look up the datasheet where are the General Purpose Registers (GPR)
and Special Purpose Registers (SPR), and be sure you do not use a speacial
register as it was a general one as you will be in trouble. It is very ugly
to use numbers as addresses, and sometimes it is very hard to remember for
them, that's why you can define names for that. For example:

myVariable   equ   0x2C

then you can say:

movf    myVariable,w
movwf   myVariable

The 'w' means the destination is the WREG register, which is also mapped
into the SPR area in some of the microcontrollers, like yours. All the SPR
are defined in the include file that you have to include somewhere in the
beginning of your asm file. Also you can declare variable names that you do
not care where are they in your memory range, like:

   cblock 0x20
   variable1
   variable2
   ...
   variableN
   endc

The 0x20 is the start of the memory block, and practically all the variables
will be put next to each other, so it happens that variable1 will be at 0x20
and variable2 at 0x21, but you should not rely on this -- use the equ
instead it you need them in the exact location.

The address space is limited, so there are several banks (like pages in a
book) that holds bunch of registers. You can 'turn pages' with special
purpose registers that are mapped to each and every pages.

All of these are much more clear in the books, and even if you feel that you
know all of these please, read it through, or at least have a glance at
every pages and if something unclear study it further.

Tamas


On 05/09/06, Lembit Soobik <lembit.piclist@t-online.de> wrote:
>
> I guess I should have said Bank, not GPR?
> >From your answer I take it that I have to address each byte (of 8 bits)
> and
> write just as I write to a variable.
> that leaves me to find out how to address it.
>
> thanks
> Lembit
>
> ----- Original Message -----
> From: "Jan-Erik Soderholm" <jan-erik.soderholm@telia.com>
> To: <piclist@mit.edu>
> Sent: Tuesday, September 05, 2006 3:47 PM
> Subject: RE: [PIC] MPASM - table write problem 18F4520
>
>
> > Lembit Soobik wrote :
> >
> >> Lets say I have 8 variables, each one Byte, named
> >> B1, B2, ... B8
> >> and I want to write them into the first GPR
> >
> > Why do you want to write them into the *same*
> > (what you call the "first") GPR ?
> >
> > And where are B1-B8 stored if not in a 8 GPR's ?
> >
> > What is it that you call "variables" ??
> >
> >> howdo I address the GPR and
> >> which instruction do I use to write (or read)
> >
> > As I said, any (almost) instruction can address the
> > GPR's. Some (like movf) reads and some (like movwf)
> > writes...
> >
> > You absolutely *HAVE* to study the data sheet again!
> >
> > In particular the part with the instruction set...
> >
> > Regards,
> > Jan-Erik.
> >
> >
> >
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
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> >
> >
> > --
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> 04.09.2006
> >
> >
>
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