Combining Ports?

I am using the P18F8720's many io pins to write usart data to a 32K
NVRAM. I don't have room for an address data latch so I am assigning:

Address(0..7) to PortD
Address(8..15)to PortJ
Data(0..8) to PortE
WE/ to PortB.0
OE/ to PortB.1

At least that is what I thought I wanted to do before I started to
write the code. Is there some way to combine PortD and PortJ to make a
16 bit register? Or some way to move values from the upper byte of
Address to PortJ and the lower byte to PortD?

I could use a chain of conditionals to move Address bytes to Ports but
it seems clunkier than necessary.

Thanks much,
           Ed V.

> Address(0..7) to PortD
> Address(8..15)to PortJ
> Data(0..8) to PortE
> WE/ to PortB.0
> OE/ to PortB.1
> 
> At least that is what I thought I wanted to do before I started to
> write the code. Is there some way to combine PortD and PortJ to make a
> 16 bit register? Or some way to move values from the upper byte of
> Address to PortJ and the lower byte to PortD?
>
> 

This chip appears to do all data operations as byte anyways, so it 
should be a simple matter to transfer the high and low bytes to the 
respective ports.
The question makes me think that you are perhaps using C, in which case 
there should be a way to get a pointer to the "two byte int" or 
something like that, then you just get one and then the next byte out of 
it like this :

int reg16;
byte * x;
x = & reg16;
PortJ = *x++;
PortD = *x;

I am just guessing about the C part, since the question appears to be 
moot by virtue of the chip operation.
T.

Thanks.

I found a C language refrence and ended up using right shift and it
worked just fine.

I will look into your pointer suggestion as I need to use that part of
my brain more often.

Ed V.


Anthony Marchini wrote:
> > Address(0..7) to PortD
> > Address(8..15)to PortJ
> > Data(0..8) to PortE
> > WE/ to PortB.0
> > OE/ to PortB.1
> >
> > At least that is what I thought I wanted to do before I started to
> > write the code. Is there some way to combine PortD and PortJ to
make a
> > 16 bit register? Or some way to move values from the upper byte of
> > Address to PortJ and the lower byte to PortD?
> >
> >
>
> This chip appears to do all data operations as byte anyways, so it
> should be a simple matter to transfer the high and low bytes to the
> respective ports.
> The question makes me think that you are perhaps using C, in which
case
> there should be a way to get a pointer to the "two byte int" or
> something like that, then you just get one and then the next byte out
of
> it like this :
>
> int reg16;
> byte * x;
> x = & reg16;
> PortJ = *x++;
> PortD = *x;
>
> I am just guessing about the C part, since the question appears to be
> moot by virtue of the chip operation.
> T.

EdV wrote:
> Thanks.
> 
> I found a C language refrence and ended up using right shift and it
> worked just fine.
> 
> I will look into your pointer suggestion as I need to use that part of
> my brain more often.
> 
> Ed V.
> 
The nice thing about pointing to the register is that it doesn't destroy 
the original as shifting will do. You won't have to make a copy before 
shifting it 8 bits and loading it out.
T.