Motorola Axiom CMD11E1 Guía de usuario descargar pdf (Pagina 19)

2.4. LOOPING 19

Exercises:

1. Assemble the following code in your PC, transfer the S19 ﬁle to HC11, run

the program and write down the output of the program.

;Name:

;email:

;date:

;

OUTA EQU $FFB8

ORG $C100

LDAB #$9 ; USING REGISTER B AS A COUNTER

LDAA #$31 ; OTHER INITIALIZATION

FOO TSTB ; SUBTRACT ZERO FROM B

BEQ BAR ; QUIT IF THE Z FLAG IS SET, I.E. B=0

JSR OUTA ; DO THE TASK

INCA ; RE-INITIALIZE

DECB ; DECREMENT THE COUNTER

BRA FOO ; GO BACK

BAR

SWI

2. Modify the above program so that the program prints the upper case letters

A to Z. Clearly indicate the changes you made.

3. The following function is equivalent to the function shown above

; continued from the previous function

ORG $C200

LDAB #$9 ; USING REGISTER B AS A COUNTER

LDAA #$31 ; OTHER INITIALIZATION

JUBJUB

JSR OUTA ; DO THE TASK

INCA ; RE-INITIALIZE

DECB ; DECREMENT THE COUNTER

BNE JUBJUB ; GO BACK

You can have as many functions as you want in the same ﬁle. Make sure that when you

change the ORG, the functions do not overlap. You can determine this by looking at the LST

ﬁle

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 100 101

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Motorola Axiom CMD11E1 Guía de usuario Pagina 19