Branch and Input –Output instructions

8/3/2019 Branch and Input –Output instructions

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Branch and Input – Output

instructions



Branch instruction



Description

1) B-Branch Unconditionally

• Syntax- B pma [, ind [,ARn]]

• Execution :pma PC

Modify (current AR) and (ARP) as specified

• Example B 191,*+,AR1

• The value 191 is loaded into the program counter, and the program

continues to execute from that location. The current auxiliary

register is incremented by 1, and ARP is set to point to auxiliary

register 1 (AR1).



2) BACC -Branch to Location Specified by Accumulator

• Syntax- BACC

• Example: BACC ;(ACC contains the value 191)

• The value 191 is loaded into the program counter, and the

program continues to execute from that location.



3)BANZ- Branch on Auxiliary Register Not Zero

• Syntax -BANZ pma [, ind [, Arn]]

Example: BANZ PGM0 ;(PGM0 labels program address 0)



4)BCND Branch Conditionally

• Syntax -BCND pma, cond1 [,cond2] [,...]

• Execution If cond1 AND cond2 AND ...

Then pma PCElse increment PC

• Example BCND PGM191,LEQ,C

If the accumulator contents are less than or equal to zero and the

carry bit is set, program address 191 is loaded into the programcounter, and the program continues to execute from that

location. If these conditions do not hold, execution continues

from location PC + 2.



5) CALA-Call Subroutine at Location Specified by Accumulator

• Syntax- CALA

• Execution -PC + 1 TOS

ACC(15:0) PCExample :CALA



6) CALL -Call Unconditionally

• Syntax -CALL pma [, ind [, Arn]]

• Execution- PC + 2 TOS

Pma PC• Example- CALL 191,*+,AR0



7) CC-Call Conditionally

• Syntax -CC pma, cond1 [,cond2] [,...]

• Execution -If cond1 AND cond2 AND ...

•Then PC + 2 TOS

• Pma PC

• Else Increment PC

• Example CC PGM191,LEQ,C

• If the accumulator contents are less than or equal to zero andthe carry bit is set, 0BFh (191) is loaded into the program

counter, and the program continues to execute from that

location. If the conditions are not met, execution continues at

the instruction following the CC instruction.



8) INTR- Software Interrupt

• Syntax- INTR K

• Execution (PC) + 1 stack

corresponding interrupt vector location PC

• Example: INTR 3

;PC + 1 is pushed onto the stack.

;Then control is passed to program

;memory location 6h.



9)NMI-Nonmaskable Interrupt

• Syntax- NMI

• Execution (PC) + 1 stack

24h PC1 INTM

• Example: NMI

;PC + 1 is pushed onto the stack, and then

;control is passed to program memory location

;24h.



10)RET-Return From Subroutine

• Syntax – RET

• Execution -(TOS) PC

Pop stack one level• Example: RET



11) RETC- Return Conditionally

• Syntax -RETC cond1 [, cond2] [,...]

• Execution -If cond1 AND cond2 AND ...

(TOS) PCPop stack one level

Else, continue

• Example: RETC GEQ,NOV ;A return is executed if the

• ;accumulator content is positive• ;or zero and if the OV (overflow)

• ;-bit is zero.



12) TRAP-software interrupt

• Syntax- TRAP

• Execution -(PC) + 1 stack

• 22h PC

• Example TRAP

• ;PC + 1 is pushed onto the stack, and then ;control is

passed to program memory location

• ;22h



I/O and Memory instructions



1) BLDD- Block Move From Data Memory to DataMemory

• Syntax- General syntax: BLDD source, destination

•

BLDD #lk, dma Direct with long immediate source• BLDD #lk, ind [, ARn] Indirect with long immediate

source

• BLDD dma, #lk Direct with long immediate destination

• BLDD ind, #lk [, ARn] Indirect with long immediatedestination



2)BLPD-Block Move From Program Memory to

Data Memory.

• Syntax General syntax: BLPD source, destination

• BLPD #pma, dma Direct with long immediate source

• BLPD #pma, ind [, ARn] Indirect with long

immediate source



3) DMOV-Data Move in Data Memory

• Syntax- DMOV dma Direct addressing

DMOV ind [, ARn] Indirect addressing

• Execution- Increment PC, then ...

(data-memory address) data-memory address + 1



4) IN -Input Data From Port

• Syntax -IN dma, PA Direct addressing

IN ind, PA [, ARn] Indirect addressing

• Example : IN 7,1000h

;Read in word from peripheral on

;port address 1000h. Store word in

;data memory location 307h (Dp=6)



5)OUT-Output Data to Port

• Syntax- OUT dma, PA Direct addressing

OUT ind, PA [, ARn] Indirect addressing



6) SPLK -Store Long-Immediate Value to Data

Memory

• Syntax -SPLK #lk, dma Direct addressing

SPLK #lk, ind [, ARn] Indirect addressing

• Execution- Increment PC, then ...

lk data-memory address



7)TBLR-Table Read

• Syntax -TBLR dma Direct addressing

TBLR ind [, ARn] Indirect addressing



8) TBLW- Table Write

• Syntax- TBLW dma Direct addressing

TBLW ind [, ARn] Indirect addressing

Branch and Input –Output instructions

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