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With the new mnemonics for 18Fxx2 chips, a "few words" explaining the new shouldbe necesary.

A.- ACCESSING MEMORY

Many mnemonmics haves a new operand called "a" (please, see datasheets. Example "addwf f,d,a". This operand selects Access Bank for a=1 or BSR register to select the correct bank.

F (a=1, Access) True Address======================================0x00..0x7F 0x000..0x07F (GPRs)0x80..0xFF 0xF80..0xFFF (SPRs)

F (a=0, BSR) BSR True Address===================================================

0x00..0xFF 0x00 0x000..0x0FF (GPRs)0x00..0xFF 0x01 0x100..0x1FF (GPRs)0x00..0xFF 0x02 0x200..0x2FF (GPRs)

... ... ...0x00..0xFF 0x0E 0xE00..0xEFF (GPRs)0x00..0xFF 0x0F 0xF00..0xFFF (GPRs/SFRs)

In JAL "f" and "a" are coded automatically based on the true address of the file (SFR or GPR), that is, if True_Address =0xF80 will be assembledwith "a=1", and the rest of files (>=0x080 or addwf H'12',f,1addwf H'072',f -> addwf H'72',f,1addwf H'FE8',f -> addwf H'E8',f,1

addwf H'084',f -> addwf H'84',f,0addwf H'123',f -> addwf H'23',f,0addwf H'F08',f -> addwf H'08',f,0

To place the correct bank automatically in the assembler statements, place the token "bank" before the menmonic. Example:

WE WRITE JAL UNDERSTAND========================================================================bank addwf H'012',f -> addwf H'12',f,1 ; nothing done, access bank.

bank addwf H'084',f -> movlb H'00' ; Bank=0addwf H'84',f,0 ; True_address=0x084

bank addwf H'123',f -> movlb H'01' ; Bank=1addwf H'23',f,0 ; True_address=0x123

bank addwf H'F08',f -> movlb H'0F' ; Bank=Faddwf H'08',f,0 ; True_address=0xF08

Outside the assembler statements, JAL also manages the hole RAM memory and selects the bank when necesary. Example:

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include f452_20

var volatile byte myvar01 at 0x0123var volatile byte myvar02 at 0x0047

myvar01 = 0x10myvar02 = 0x10

;; 006 : var volatile byte myvar01 at 0x0123; var H'123:000' myvar01

;; 007 : var volatile byte myvar02 at 0x0047; var H'047:000' myvar02

;; 009 : myvar01 = 0x10

movlw H'10'movlb H'01' ; bank=1movwf H'123' ; true_address=0x123

;; 010 : myvar02 = 0x10movlw H'10'movwf H'047' ; access_bank ; true_address=0x047

Available RAM for current PIC_16 core supported chips:

PIC18F242 0x000..0x2FF & 0xF80..0xFFF

PIC18F252 0x000..0x5FF & 0xF80..0xFFFPIC18F442 0x000..0x2FF & 0xF80..0xFFFPIC18F452 0x000..0x5FF & 0xF80..0xFFF

B.- INDIRECT MEMORY ACCFESS

In PIC_14 chips (PIC16F84, PIC16F877, etc.) we have 2 SFRs for indirect addressing: FSR that holds the address (I'm not to talk now about IRP bit, so I leftthis as is) and INDF that manages the data of the file pointed by the FSR register.

In a simple description:

var byte myvar

FSR = 0x67 -- We put here the address of the file.

myvar = INDF -- The file "myvar" haves now a copy of the-- data stored in the address 0x67.

With PIC_16 cores this is enhanced by 3 diferent FSRs (address holders) and 5diferent INDF for each one of the FSRs.

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As the RAM memory it's larger than a byte (0..255) the FSRs are splitted in 2registers for High byte of the address and Low byte of the address.

SFR name Address Description=========================================FSR0H 0xFEA High byte of FSR0 (address holder #0)

FSR0L 0xFE9 Low byte of FSR0 (address holder #0)-----------------------------------------FSR1H 0xFE2 High byte of FSR1 (address holder #1)FSR1L 0xFE1 Low byte of FSR1 (address holder #1)-----------------------------------------FSR2H 0xFDA High byte of FSR2 (address holder #2)FSR2L 0xFD9 Low byte of FSR2 (address holder #2)

With these registers we can select any address on the chip. Example:

FSR0H == 0x00FSR0L == 0x23 -- FSR0 = 0x023

FSR1H == 0x02FSR1L == 0x44 -- FSR1 = 0x244

FSR2H == 0x0FFSR2L == 0xFC -- FSR2 = 0xFFC

assembler

LFSR 0,0x0023 ; FSR0 = 0x023

LFSR 1,0x0244 ; FSR1 = 0x244LFSR 2,0x0FFC ; FSR2 = 0xFFC

end assembler

In order to manage the data pointed by FSRs we have the INDFs registers. Theyhave the following meaning:

SFR name Address Description===========================================INDF0 0xFEF Uses the content of FSR0 to address

data memory. FSR0 not changed.

POSTINC0 0xFEE Uses the content of FSR0 to addressdata memory. FSR0 is post-incremented by 1.

POSTDEC0 0xFED Uses the content of FSR0 to addressdata memory. FSR0 is post-decremented by 1.

PREINC0 0xFEC Uses the content of FSR0 to addressdata memory. FSR0 is pre-incremented by 1.

PLUSW0 0xFEB Uses the content of FSR0 and W as offset to

address data memory. FSR0 not changed.----------------------------------------------------------------------INDF1 0xFE7 Uses the content of FSR1 to address

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data memory. FSR1 not changed.

POSTINC1 0xFE6 Uses the content of FSR1 to addressdata memory. FSR1 is post-incremented by 1.

POSTDEC1 0xFE5 Uses the content of FSR1 to addressdata memory. FSR1 is post-decremented by 1.

PREINC1 0xFE4 Uses the content of FSR1 to addressdata memory. FSR1 is pre-incremented by 1.

PLUSW1 0xFE3 Uses the content of FSR1 and W as offset toaddress data memory. FSR1 not changed.

----------------------------------------------------------------------INDF2 0xFDF Uses the content of FSR2 to address

data memory. FSR2 not changed.

POSTINC2 0xFDE Uses the content of FSR2 to addressdata memory. FSR2 is post-incremented by 1.

POSTDEC2 0xFDD Uses the content of FSR2 to addressdata memory. FSR2 is post-decremented by 1.

PREINC2 0xFDC Uses the content of FSR2 to addressdata memory. FSR2 is pre-incremented by 1.

PLUSW2 0xFDB Uses the content of FSR2 and W as offset toaddress data memory. FSR2 not changed.

----------------------------------------------------------------------

Some examples:

-- Initialize the FSRsassembler

LFSR 0,0x0100 ; FSR0 = 0x100LFSR 1,0x0200 ; FSR1 = 0x200LFSR 2,0x0300 ; FSR2 = 0x300

end assembler

-- Store some value into 0x100..0x123, 0x200..0x223, 0x200..0x223.-- 105 bytes changed with this loop:for 0x23 loop -- assigmentPOSTINC0 = 0x00 -- [FSR0]

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INDF1 = " " -- [FSR1]

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BNZ Branch if not zeroBOV Branch if overflowBNOV Branch if not overflowBRA Branch unconditionallyRCALL Relative call

C.- NEW MNEMONICS

Please, read datasheets to know each one. But take care that "MOVFF" it's notimplemented yet.