The CDF Engineer Recruitment Test

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Instructions for attempting Test:Please follow the following instructions explicitly.

1- Copy and paste the entire test to MS Word

2- Write answers below each question. You have until the deadline below to work on this test freely.

3- Section 0 is mandatory to attempt

4- From Section 1 – 5, you will only be graded against the best two sections answered. The rest will not be considered in the evaluation.

5- We suggest you attempt all questions

6- You are encouraged to use online materials, textbooks and other reference guides to answer

6- When finished, email the completed document to jobs@coreframeworks.com.

7- Based on the results of the test, we will get back to you within a few days.

Also, please note the following:

  • Test can be submitted only once
  • Please Attach your NIC copy (or number) with the test
  • Explicitly mention the job position in the email subject


Section 0: General Questions


Question 1

Situation: You were asked to come up with the object level design for one module of the system. Your design reflects your experience on similar work in the past. However, some seniors in the company disapprove of your design and ask you to implement the solution another way. They do not seem to have any basis for their request except that they have another perspective for the application in their minds. What’s more, you feel that your design would be more efficient for the particular situation. What would you do?


Question 2

You are a key part of a team that is building an important software product for a client. You have 5 days before go-live, and your team is on-track to make the software ready for production by then. You are personally responsible for the most critical portion of the project.

The client will be formally launching this application globally from a special Launch Event that will be held in 5 days. The client has booked a 3000-seat conference hall for the launch event, and all the preparations are in place. More than 500 news reporters from leading international news magazines will be attending.

Today, you find out that a close family member — your father — has suddenly fallen ill, and will need to be hospitalized for one week. He will need your close support and attention.

Realizing how much is at stake, what would you propose to your supervisor what the company should do in this situation? How would you present the situation to the supervisor? (Please explain less than 20 lines)


Question 3

You are given a project by a client that needs 80 man-hours for development of a certain item, and you have 3 other team members to complete the project. Given a deadline of two weeks, tell us how you would divide your work into phases according to time in order to successfully release the software to the clients


Question 4

Improve on the usability and user-friendliness of the following remote control, keeping the following in mind:

  • The gadget is multi-purposed: It can be used as a garage-opener and a TV remote.
  • The gadget will be made specially for elderly people.


Primary functionality includes:

1. Changing channels
2. Adjusting volume
3. Opening and closing the garage

You can change anything from the color to the positions of the buttons. You can also remove any buttons that you wish, or add additional buttons provided you state their purpose clearly.



Section 1: Software Questions


Question 1

Q: What does the following code do? (describe in 3 lines in english)

 ( (n & (n-1) == 0) //n = 2,3,4,5...

Question 2

Q: Write out the console output that would be seen with the following code. If it is incorrect, describe how to fix it.

unsigned int i;
for (i = 100; i <= 0; –i)
printf(“%d\n”,i);


Question 3

Q: Describe how to create an object oriented program in ANSI-C
(40 lines or less)


Question 4

Q: Write ANSI-C code to count the number of ONE bits in an integer
A- Write an iterative solution
B- Write a recursive solution
C- Compare the two
D- In what type of software is this algorithm commonly used?


Question 5

Q: Write down the code that implements a state-graph as a circular singly linked list data structure. These are the requirements:

  • The linked list will be used to implement a state-graph.
    • Every state will be implemented as a function, and the linked list will contain pointers to each of the functions that describe states.
    • The state machine will keep looping through the entire list to execute the states
  • The total code must not be longer than 5 lines of software.
  • The language used must be ANSI-C without any vendor-specific API / data stucture (e.g. no VC.net / C# artifacts)

[Hint: You can assume that the size of the address bus (pointer size) is 2 bytes]
Write down any assumptions you take in the code with regards to the behaviour of the functions



Section 2: Embedded Software Questions


Question 1


Q. When would context-switching become a prohibitive bottleneck in real-time system performance? Why? Cite some examples.


Question 2

Q:
A- Describe, in english, what the mysteryFunction below does

unsigned short mysteryFunction(const unsigned short num){
 unsigned short patternOne = 0x55;
 unsigned short patternTwo = 0xAA; 

 patternTwo &= num;
 patternOne &= num; 

 patternTwo <<= 1;
 patternOne >>= 1; 

 return (patternOne | patternTwo);
}

B- The code segment above is too inefficient — it takes up too much stack space and uses many load / store instructions.
Re-write the above function so that it is more efficient
(Hint: Only one line of code is needed, and it should not use any local variables)


Question 3

Q: You were trying to implement the FAT file system into the design of a new device but is too large to fit into your system.

Design a minimal file system structure. What are the most essential functions that will exist in the file system structure? How would you determine the size of the blocks?


Question 4

Q:
A- What is a state machine?
[Research online] [Answer in less than 5 lines]
B- How can a state machine be implemented in software using recursion?
C- A state machine was implemented recursively, but this has started to result in stack overflows. Why is this occuring?
D- Assuming the error in (C) occurs exactly because of the reason you have given, how would the implementation be fixed in order to prevent those overflows?


Question 5

Q:
You just finish creating embedded software that will run on a micro-controller. You have the software connected to an LCD device temporarily so that you can print out debug traces.

The software implements a communication protocol, which is sending digital data to the processor at 66Hz.

However, when you start testing you find that your application never receives the data, even when it is sent to it. You step through every single line of code, but there are no evident errors in any line. The debug traces all show that the values are valid throughout the test. However, the receive buffer only gets the first two bytes from the incoming data.

You also check the communication link thoroughly and there are no packet / byte losses on the line.

What could be the cause of this error? How would you fix it?


Question 6

Q.
A- Write pseudo-code that decompresses a JPEG image and shows it on the screen. (you may find the JPEG decoding algorithm online)

B- In which parts of this code can further optimizations be made? (i.e. by design, which of the parts can be refined without breaking the algorithm)

C- If you were to implement this in C, which data structures would you use to get the best performance from the code? Compare a number of data structures.

D- How would your choice of data structures change if you were using C++?

E- How would your choice of data structures change if you were using multi-threading?



Section 3: Platform Software Questions


Question 1

Q:
A) What is the difference between a thread and a process?

B) When would you want to create a multi-processed application but not a multi-threaded application?


Question 2

Q:
A) What is the general purpose of a heartbeat server? (research online) (answer in less than 5 lines)

B) Describe one good example of a system that can use a heartbeat server, and one bad example of such a system.

C) The heart-beat mechanism may be prohibitively inaccurate for certain types of systems — Name one example where that is true. How could we improve this mechanism for that system? Describe your recommendations. (less than 5 lines)


Question 3

Q: How would you implement a tree-based data structure as an array?

A- Describe the implementation — how would the array by structured [Answer in less than 10 lines]

B- Write pseudo-code (or C/C++ code) to find any item in the ‘tree’

C- How would you add or remove items from the ‘tree’?

[Describe in 5 lines]


Question 4

Q: Is it possible to create a piece of software that calculates the fibonacci sequence with a total run-time cost of 0 (zero)? If so, how could that be done? (Just describe the basic technique used)

[Hint: A run-time cost of zero means that the program calculates the results of the fibonacci even before the code is executed]


Question 5

Q:
One of your applications has the following infrastructure architecture:

Your software application will be installed on multiple servers in order to serve the total set of requests for it.

To make the system architecture simpler, all of those servers are bound together into one virtual server cluster. For each incoming request, the ‘virtual server manager’ will decide which actual machine to send the request to.

A) Describe the high-level steps for a load-balancing algorithm to implement on the ‘virtual server manager’ that will ensure that all physical servers are used evenly. (answer in less than 40 lines)
The basic requirements are:

  • Each incoming request should be sent to the server that is the ‘least busy’ at that time.
  • All requests will be executed by the actual server (after being forwarded) in a fixed amount of time.
  • All the requests will be processed with different priorities at the ‘virtual server manager’ — ‘high-priority’ requests will always be processed first, and then ‘low-priority’ requests.
  • All the requests must be processed and forwarded by the ‘virtual server manager’ within a limited time. The manager cannot “store” the requests to “forward” at a later time.

Your design must describe how:

  1. The virtual server manager will determine which server is ‘free’
  2. How your scheme will process requests of different priorities — what happens if a low-priority request is received followed immediately by a high-priority request.
  3. The scheme ensures that all requests are forwarded in real-time, given that “Store-and-forward” cannot be used as a message forwarding scheme.

B) Would you recommend another infrastructure design (i.e. rearraging the servers to make the system more optimal?) Describe your recommended solution (not more than 3 lines)



Section 4: Hardware and Digital Logic Questions


Question 1

A- Compare the difference between using an IRQ line and key-wakeup interrupts to connect peripheral ICs (from a hardware perspective).

B- How is “addressing” implemented in a system-wide bus that connects the processors with peripheral ICs?


Question 2

A- How are display buffers implemented in hardware? (Research online)

B- Suppose the implementation you described in (A) is used in a laptop. How would your implementation change if a Smart-LCD was used in the laptop?


Question 3

Q) A- Build the technical design of a basic computer CD-ROM player. The basic requirements are:

  • Should be able to play music CDs
  • Should have a simple data redundancy and protection scheme on it

Describe the functional blocks of the hardware and software system, as well as physical-level design and schematics.

B- Describe, in high-level pseudo-code, the logic embedded into the CDROM micro-controller.

C- At what RPMs would the central CD-Rom motor run in order to play music CDs? Write the steps of the calculation. What type of motor would this be?

D- How would you create an abstracted API for the CDROM that is exposed to the application-software? How would you make the API transparent from the data-redundancy checks? Explain the design (30 lines or less).

E- Write the specification number and online web-link to the International Standards document that covers the design of modern-day CD-Rom systems and software. (I.e. find this online and enter it here)


Question 4

Q) Your team has designed a hardware product, which is nearing final production. All manufacturing contracts are ready, and production is about to ramp up. The PCBs are being manufactured, so are the plastic housings.

A beta test is organized, where 1000 units of the product are given to customers to test for free. During the Beta Test, your customers tell you that the product does not have an ON/OFF (power) switch, and because of that the product is very confusing.

A) How will you present this to the management as a trade-off? (Write down examples)

B) If management decides that the switch must be included, but that no deadlines can be changed, what will be the quickest and least-cost way of incorporating the switch in the design?


Question 5

You are hired by a leading commercial airplane manufacturer. They think that the cockpit of the plane has too many levers and buttons, and they want to create a brand new cockpit dashboard based on touchscreen computer displays (as in ATM machines).

The requirement of the new dashboard is “the pilot should immediately be able to find the option he wants, when he wants to find it, based on the action he is performing at that moment”.

E.g. During takeoff or landing, it may be helpful to see the controls related to the landing gear. At other points during the flight, those controls may not be visible.

Describe what you would propose as the design of the hardware of the system



Section 5: GUI and Usability Design


Question 1

A- How are display buffers implemented in the firmware / OS of a device (research online)?

B- How is 24-bit RGB display data stored in the buffer? Describe for a 1024×768 pixel screen. (Research Online)

C- A device has a display buffer that shows a picture. The picture is stored in 24-bit RGB. You want to give the user the ability to rotate the image 90 degrees (as is common in current day imaging programs). Describe the algorithm (in high-level pseudo code) to achieve this.

D- What are the major bottlenecks of your algorithm from (C)? Can you optimize the algorithm further by creating abstracted representations of the data?


Question 2

Describe the functional software blocks of the design of a “layered” windowing system. The requirements are

* All applications will always exist as ‘full screen windows’.

* All the open applications will existing in an individual layer, and only the ‘active’ application will be visible at the top layer.

* Layers can be moved up and down in the stack order.


Question 3

A- Compared to Windows XP, what is special about icons in the “Apple Aqua” or ‘Glossy’ UI look? [Research Online] [Be explicit about the technical visual differences]

B- Suppose one of our clients is Microsoft, and they ask you to create an enhancement to their Windows GUI in C++ that will automatically create the ‘glossy’ look from all their existing icon files. Your piece of software will be triggered from the “icon file loader” module in the software. Describe what algorithm your software will implement (high-level logic)

C- What — in your opinion — should the design be of a “brushed metal” GUI? What about a “piano black” GUI? How would those be implemented in software (design the key high-level logic of the algorithms involved)


Question 4

Your clients have given you an application that they have a hard time using, because they find the user interface confusing. They would like you to suggest improvements.

A- The application categorizes all of their products together in a tree-based visual structure (just like Windows explorer), but the clients have to click too many times to find relevant products, and relevant related accessories to the products. How would you propose the software UI be changed to address this issue (you can describe changes at the control level, the data representation level, or even just in the visual style such as colors.) [Explain your answer in 30 lines or less]

B- The application makes the users add a product, add accessories, add discounts, add shipping partners, add credit card information, and finally package this all together as a report. However, currently they have to go through a series of 6 screens in order to do all of this (clicking ‘next’ along the way). Now, they would like all of this work to happen from the same screen. Propose a UI to them [You may attach a rough sketch diagram, or CLEARLY describe in 30 lines or less]

C- The client tries to implement a solution to the issue in (B). Now, they have one screen but it has almost 80 different text fields in forms to fill in. The client gives you the following requirement “Make this so intuitive that it is dramatically easier to use”. What would you propose to the client?


Question 5

Sometimes, in software, icons or graphics “fly-out” of a certain part of the screen.

A- How is the animation actually implemented in software? [Research online]

B- There might be different ‘animation splines’ for different types of behaviour of the software. Describe how animation splines would be stored as a data stucture. How would the UI Control or Graphic know which Spline to use for a particular animation?


Question 6

A- How are GUI Resources (images, text styles etc.) stored on the disk in traditional windowing systems? Compare CSS with the design of MFC, .NET, and Linux Gnome and Linux X-Server. [You are encouraged to research this online. Answer in less than 15 lines]

B- Often the performance bottleneck becomes the code that loads up the resources from the disk before displaying them on screen. This is because accessing the disk each time takes a long time, and because there are many disk accesses.

Describe key design points of a software / algorithm which could improve the performance of the resource loader. The design should attempt to minimize the disk access.

E.g if you think a cache would help, describe the caching scheme. Other suggested approaches are also welcome.

Facebook comments:

2 Comments

  • MUDASSER HAMEED

    I received job news on yahoo group of FAST-NU students on 12th of October 2006. I am not sure whether I must apply now or not. Please reply me if you can give us any benifit in this regard. Thanks
    Regards,
    Mudasser Hameed

  • Imran Mehmood

    I too got this news far after its deadline. So if we submit this test now will you consider us for these jobs or for jobs in future.
    Regards,
    Imran Mehmood

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