Exam (elaborations)
1.3.4-Output-devices
- Course
- Institution
1.3.4-Output-devices
[Show more]
Seller
Follow
Hkane
Reviews received
Content preview
QUESTION 1. 128 An alarm clock is controlled by a microprocessor. It uses the 24 hour clock. The hour is represented
by an 8-bit register, A, and the number of minutes is represented by another 8-bit register, B.
(a) Identify what time is represented by the following two 8-bit registers.
A B
128 64 32 16 8 4 2 1 128 64 32 16 8 4 2 1
0 0 0 1 0 0 1 0 : 0 0 1 1 0 1 0 1
Hours ............................................ Minutes .........................................
[2]
(b) An alarm has been set for 07:30. Two 8-bit registers, C and D, are used to represent the
hours and minutes of the alarm time.
Show how 07:30 would be represented by these two registers:
C D
:
Hours Minutes
[2]
(c) Describe how the microprocessor can determine when to sound the clock alarm.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
© UCLES 2015 0478/11/M/J/15
, 13
(d) The LCD (liquid crystal display) on the clock face is back-lit using blue LEDs (light emitting
diodes). The brightness of the clock face is determined by the level of light in the room. The
amount of light given out by the LEDs is controlled by a control circuit.
Describe how the sensor, microprocessor and LEDs are used to maintain the correct
brightness of the clock face.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
(e) Modern LCD monitors and televisions use LED back-lit technology.
Give two advantages of using this new technology compared to the older cold cathode
fluorescent lamp (CCFL) method.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
© UCLES 2015 0478/11/M/J/15 [Turn over
, QUESTION 2. 4
3 Four input devices, four descriptions and four applications are shown below.
Draw a line to connect each input device to its correct description. Then connect each description
to its correct application.
Input device Description Application
copies paper documents and
voice
barcode reader converts the text and pictures
recognition
into a computer-readable form
reads labels containing parallel
microphone dark and light lines using laser reading
light or LEDs; the width of each passports
line represents a binary code
detects changes in acidity
automatic stock
pH sensor levels; data is often in
control
analogue form
device that allows audio
signals to be converted into
monitor soil in a
scanner electric signals; these can be
greenhouse
interpreted by a computer after
being converted into digital form
[6]
© UCLES 2015 0478/12/M/J/15
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Hkane. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79650 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now