>Stewart Pye wrote:
>>
>> I know you can define bytes in rom using the db command,
>> What is the best way to access these???
>> ( I'm lost without a data pointer!! )
>
>An easier way to implement lookup tables is in Microchip Application
>Note 556.  The simplified version is copied below, but read the
>App. Note for the full scoop.
>
>== BEGIN CODE ==
>  .
>  movlw offset ;load offset in w reg
>  call Table
>  .
>  .
>  .
>Table:
>  addwf pcl ;add offset to pc to
>            ;generate a computed goto
>  retlw 'A' ;return the ASCII char A
>  retlw 'B' ;return the ASCII char B
>  retlw 'C' ;return the ASCII char C
>  .
>  .
>== END CODE ==
>
>Regards,
>
>Roy Tate
>roytateKILLspamionet.net
>http://www.ionet.net/~roytate
>

>> I was wondering, for the case of the 16F84, how many characters can we
>put
>> in tables? Does this depend on the size of your program or is there space
>> reserved just for tables in the memory of the MCU?
>
>No spare MCU space, unless you want to use the 64 bytes data eeprom.
>Coding a table larger than 256 entries is more complex than smaller tables
>(because you must essentially first brach ff to the correct table).
>So the upper limit is the 1K code.
>beyond that you must add e.g. an external serial eprom.
>
>Wouter
>