COE 538 Quiz

Name: _____________________________ Student #: __________________ Time: 50 min.

Notes:

1. Close book
2. Neatly write the answers in the space provided
3. The Instruction Set can be detached

1. Write assembler directives to reserve 100 bytes from $6000. [1 mark]

ORG $6000

RMB 100

2. Assume that the E-clock signal frequency is 1 MHz. Write a program to create a time delay of 100 µS. [3 marks]

LDY #14

del DEY

BNE del

3. Given a program listing below, trace the results for each instruction from start to end. What are the contents of the memory locations at $6010 and $6011 after the execution of the swi instruction? [6 marks]

Note: ASCII codes for characters t, =, and @, are $74, $3D, and $40 respectively.

org $6000

temp fcc ‘t=@’

org $6010

res fdb $4, $20

org $6050

start ldx #temp ;x = $6000

ldaa 2, x ;a = $40

ldy #res ;y = $6010

ldab 1, y ;b = $04

end mul ;d = $0101

loop deca

bne loop

std res [$6010] = 00 [$6011] = 00

swi

4. Write a program (only one program):

- to multiply the contents of the memory location at $6000 by the contents of the memory location at $6001 [2 marks]

- to add the contents of the memory location at $6050 to the product computed above and save the result at $7000 and $7001 [3 marks]

LDAA $6000

LDAB $6001

MUL

ADDD $6050

STD $7000

5. Write a code that sets two most significant bits and clears two least significant bits of Accumulator A. [2 marks]

ORAA #% 1100 0000

ANDA #% 1111 1100

6. Assume that the result of the A-to-D conversion of a DC voltage V_x at the channel 0 of the ADC is $57. What is the value of the voltage V_x in Volts, if V_REFL=0 V and V_REFH=5 V? [2 marks]

$57 = 87

255 / 87 = 5 / V_x

V_x = 5x87 / 255 = 1.71 [V]