The ASRS08 assembler supports the RS08 series of micropro-
cessors. Processor specific definition files are included for
the KA2(KA1), KA8(KA4), KB8( KB2, KB4, and KB6), LA8, and LE4
variations of peripheral options with the RS08 core.
RS08 REGISTER SET
The following is a list of the RS08 registers used by ASRS08:
a - the accumulator
x - the index register
RS08 ARGUMENT SYNTAX
a 8 bit accumulator register
x 8 bit index register
#opr8i 8 bit immediate value
(#)n 3 bit data
M is a memory address
opr16a 16 bit address
opr8a 8 bit address
opr5a 5 bit address (0 <= opra5 <= 31)
opra4 4 bit address (0 <= opra4 <= 15)
Force the opr8a address form using the * prefix
Force the opr5a or opr4a form using the <* prefix
rel -128 to +127 relative address
,x indexed addressing
D[X] indexed addressing
The terms opr8i, n, opr16a, opr8a, opra5, opra4, and rel may be
expressions.
Note that not all addressing modes are valid with every in-
struction. Refer to the RS08 reference manual for more details.
RS08 INSTRUCTIONS
The following tables list the mnemonics and arguments recog-
nized by the ASRS08 assembler.
The operational description of the instructions may
contain one or more of the following forms:
A is a register
X is a register
C is the Carry Bit
n is a 3 Bit Value
# is an immediate value
(arg) - 'The Contents Of' arg
(Mx) - 'The Contents Of M Addressed By (x)'
Load and Store Instructions
lda #opr8i A <- #
lda opr8a A <- (M)
lda opra5 A <- (M)
lda ,x A <- (Mx)
lda D[X] A <- (Mx)
ldx #opr8i X <- #
ldx opr8a X <- (M)
ldx ,x X <- (Mx)
ldx D[X] X <- (Mx)
sta opr8a (M) <- (A)
sta opr5a (M) <- (A)
sta ,x (Mx) <- (A)
sta D[X] (Mx) <- (A)
stx opr8a (M) <- (X)
tax X <- (A)
txa A <- (X)
BSET, BCLR, and Move Instructions
bclr n,opr8a Bit n of (M) <- 0
bclr n,x Bit n of (Mx) <- 0
bclr n,D[X] Bit n of (Mx) <- 0
bset n,opr8a Bit n of (M) <- 1
bset n,x Bit n of (Mx) <- 1
bset n,D[X] Bit n of (Mx) <- 1
mov opr8a,opr8a (M)dst <- (M)src
mov #opr8i,opr8a (M) <- #
mov ,x,opr8a (M) <- (Mx)
mov D[X],opr8a (M) <- (Mx)
mov opr8a,D[X] (Mx) <- (M)
mov #opr8i,D[X] (Mx) <- #
Add and Subtract Instructions
adc #opr8i A <- (A) + (C) + #
adc opr8a A <- (A) + (C) + (M)
adc ,x A <- (A) + (C) + (Mx)
adc D[X] A <- (A) + (C) + (Mx)
adc x A <- (A) + (C) + (x)
adcx A <- (A) + (C) + (x)
add #opr8i A <- (A) + #
add opr8a A <- (A) + (M)
add opr4a A <- (A) + (M)
add ,x A <- (A) + (Mx)
add D[X] A <- (A) + (Mx)
add x A <- (A) + (x)
addx A <- (A) + (x)
sbc #opr8i A <- (A) - (C) - #
sbc opr8a A <- (A) - (C) - (M)
sbc ,x A <- (A) - (C) - (Mx)
sbc D[X] A <- (A) - (C) - (Mx)
sbc x A <- (A) - (C) - (x)
sbcx A <- (A) - (C) - (x)
sub #opr8i A <- (A) - #
sub opr8a A <- (A) - (M)
sub opr4a A <- (A) - (M)
sub ,x A <- (A) - (Mx)
sub D[X] A <- (A) - (Mx)
sub x A <- (A) - (x)
subx A <- (A) - (x)
Other Arithmetic Instructions
inc opr8a (M) <- (M) + 1
inc opr4a (M) <- (M) + 1
inc ,x (Mx) <- (Mx) + 1
inc D[X] (Mx) <- (Mx) + 1
inc a A <- (A) + 1
inc x X <- (X) + 1
inca A <- (A) + 1
incx X <- (X) + 1
dec opr8a (M) <- (M) - 1
dec opr4a (M) <- (M) - 1
dec ,x (Mx) <- (Mx) - 1
dec D[X] (Mx) <- (Mx) - 1
dec a A <- (A) - 1
dec x X <- (X) - 1
deca A <- (A) - 1
decx X <- (X) - 1
clr opr8a (M) <- 0
clr opr4a (M) <- 0
clr ,x (Mx) <- 0
clr D[X] (Mx) <- 0
clr a A <- 0
clr x X <- 0
clra A <- 0
clrx X <- 0
cmp #opr8i (A) - #
cmp opr8a (A) - (M)
cmp ,x (A) - (Mx)
cmp D[X] (A) - (Mx)
cmp x (A) - (X)
cmpx (A) - (X)
tst opr8a (M) - 0
tst ,x (Mx) - 0
tst D[X] (Mx) - 0
tst a (A) - 0
tst x (X) - 0
tsta (A) - 0
tstx (X) - 0
Logical Operation Instructions
and #opr8i A <- (A) & #
and opr8a A <- (A) & (M)
and ,x A <- (A) & (Mx)
and D[X] A <- (A) & (Mx)
and x A <- (A) & (X)
andx A <- (A) & (X)
ora #opr8i A <- (A) | #
ora opr8a A <- (A) | (M)
ora ,x A <- (A) | (Mx)
ora D[X] A <- (A) | (Mx)
ora x A <- (A) | (X)
orax A <- (A) | (X)
eor #opr8i A <- (A) ^ #
eor opr8a A <- (A) ^ (M)
eor ,x A <- (A) ^ (Mx)
eor D[X] A <- (A) ^ (Mx)
eor x A <- (A) ^ (X)
eorx A <- (A) ^ (X)
com a A <- ~(A)
coma A <- ~(A)
Shift and Rotate Instructions
asl a C <- (A7) Left Shift (A0) <- 0
asla C <- (A7) Left Shift (A0) <- 0
lsl a C <- (A7) Left Shift (A0) <- 0
lsla C <- (A7) Left Shift (A0) <- 0
lsr a 0 -> (A7) Right Shift (A0) -> C
lsra 0 -> (A7) Right Shift (A0) -> C
rol a C <- (A7) Left Rotate (A0) <- C
rola C <- (A7) Left Rotate (A0) <- C
ror a C -> (A7) Right Rotate (A0) -> C
rora C -> (A7) Right Rotate (A0) -> C
Jump and Branch Instructions
jmp opr16a PC <- Adrress
bcc rel Branch if Carry Bit Clear
bcs rel Branch if Carry Bit Set (blo)
beq rel Branch if Zero Bit Set
bhs rel Branch if Higher or Same (bcc)
blo rel Branch if Lower (bcs)
bne rel Branh if Zero Bit Clear
bra rel Branch Always
brn rel Branch Never
Bit Branches and Loop Control Instructions
brclr n,opr8a,rel Branch if Bit n of (M) is Clear
brclr n,D[X],rel Branch if Bit n of (Mx) is Clear
brclr n,x,rel Branch if Bit n of (x) is Clear
brset n,opr8a,rel Branch if Bit n of (M) is Set
brset n,D[X],rel Branch if Bit n of (Mx) is Set
brset n,x,rel Branch if Bit n of (x) is Set
cbeqa #opr8i,rel Branch if (A) = #
cbeq a,#opr8i,rel Branch if (A) = #
cbeq opr8a,rel Branch if (M) = 0
cbeq ,x,rel Branch if (Mx) = 0
cbeq D[X],rel Branch if (Mx) = 0
cbeqx rel Branch if (X) = 0
cbeq x,rel Branch if (X) = 0
dbnz opr8a,rel (M) <- (M) - 1, Branch if (M) != 0
dbnz ,x,rel (Mx) <- (Mx) - 1, Branch if (Mx) != 0
dbnz D[X],rel (Mx) <- (Mx) - 1, Branch if (Mx) != 0
dbnz a,rel A <- (A) - 1, Branch if (A) != 0
dbnza rel A <- (A) - 1, Branch if (A) != 0
dbnz x,rel X <- (X) - 1, Branch if (X) != 0
dbnzx rel X <- (X) - 1, Branch if (X) != 0
Subroutine Related Instructions
bsr rel Branch to Subroutine
jsr opr16a Jump to Subroutine
rts Return from Subroutine
sha (A) <--> Shadow PC High
sla (A) <--> Shadow PC Low
Miscellaneous Instructions
nop No Operation
sec (C) <- 1
clc (C) <- 0
bgnd Background
wait Put MCU into wait mode
stop Put MCU into stop mode
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Last Updated: September 2023