Senior hardware engineer Interview Questions | Glassdoor

# Senior hardware engineer Interview Questions

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### Senior Hardware Verification Engineer at NVIDIA was asked...

Jan 29, 2010
 Describe a function to check if an integer is a power of 2.6 AnswersFor an integer n: If n is less than 1, return false. If the bitwise & of n and n-1 is 0, return true. Otherwise, return false.Write the number in binary and count the number of ones in that.If the number os ones is only 1 then it the number is indeed a power of 2first check if no is 1 then return false else write the number in binary and then check number of ones in that.if only one 1 is there then its a power of 2Show More ResponsesI think the main idea is to use recursion function, for the integer which is larger than 0, if it is 1 return true, else return function(n-1)See if the sum of all bits is 1. If that's the case then the number is a power of 2.function int power2(int i); if (i%2==1) return 0; else if (i/2==1) return 1; else return power2(i/2); endfunction

### Senior Hardware Engineer at Apple was asked...

Aug 1, 2014
 If you have a 10W light bulb and a 100W light bulb, and you connect them together, which one will be brighter?7 AnswersIf you connect them in parallel, obviously the 100W bulb will be brighter. But if you connect them in series, the 10W bulb will almost certainly be brighter because it limits the current going to the 100W bulb to a fraction of its normal operating current. This assumes by "brightness" you really mean total radiated power in visible + IR wavelengths, and that both bulbs have "brightness" linear with power.I do not agree with answer for "in-series". Must have been the next to last question you had on the last day. What incadescent bulb will current limit? Assuming incandescent bulbs, the bulbs would act as a voltage divider and the 100W bulb would still give off more light (lumens in the visible spectrum) than the 10W bullb. Use an analysis whereby use a smaller resistor for 100W and a 10x higher resistance for 10W bulb. Each bulb will be alittle dimmer than in parallel, but 100W still brighter. Fluorescent bulbs would be a whole new story. Would they even work at lower voltages?@Don you are correct up until your conclusion that "Each bulb will be a little dimmer than in parallel, but 100W still brighter." The 100W bulb is 10x dimmer if you assume resistance does not depend on current. Reality is even worse since R increases with current. Since the 10W bulb has 10x higher resistance than 100W bulb, it will absorb 10x as much power in the voltage divider: 100W bulb = 1A at 100V, or 100 ohms 10W bulb = 0.1A at 100V, or 1000 ohms 100W bulb + 10W bulb in series driven off 110V line is 1100 ohms carrying 0.1A of current. Power delivered to 10W bulb is P = I^2 x R = (0.1A)^2 x (1000 ohm) = 10W. Power delivered to 100W bulb is P = (0.1A)^2 x (100 ohm) = 1W. So the 100W bulb only receives 1W delivered power because the 10W bulb absorbs all the power in the divider. The 10W bulb will be brighter.Show More ResponsesCase 1: Bulbs B1, B2 are connected in series. Same current flows through B1 and B2. P = I^2 / R. And given P1 = 10 and P2 = 100. So, R2 = 10*R1 =>B1 will be brighter. Case 2: Bulbs B1, B2 are connected in parallel. Same voltage across B1 and B2. P = V*I. So, I2 = 10*I1 =>B2 will be brighter.1. When connected in series: In a series connection, current flowing across each element is same. So when 40W bulb and 60W bulb are connected in series, same current will flow through them. To find which bulb will glow brighter we need to find the power dissipation across each of them. From the relation P=(I*I) R since current is same we can say that power dissipation will be higher for the bulb with higher resistance i.e. 40W bulb. Hence 40W bulb will glow brighter in series connection. 2. When connected in parallel: In a parallel connection, voltage across each element is same. So when 40W bulb and 60W bulb are connected in parallel, voltage across them will be same (100 V in the given case). To find which bulb will glow brighter we need to find the power dissipation across each of them. From the relation P=(V*V)/R since voltage is same we can say that power dissipation will be higher for the bulb with lower resistance i.e. 60W bulb. Hence 60W bulb will glow brighter in parallel connection.Above parallel connection are good, but when connected in series 10W bulb cannot handle 100W current and filament will fail, then no bulb will be ON.The 100W bulb will always be brighter as long as it's working on its nominal voltage. End of story.

### Senior Hardware Verification Engineer at NVIDIA was asked...

Jan 29, 2010
 Describe a circuit that implements the following truth table using only NAND gates. A B OUT 0 0 1 0 1 1 1 0 0 1 1 17 Answers((A NAND B) NAND C)out = (A NAND (B NAND B))out = ((A NAND A) NAND (A NAND A)) NAND (B NAND B)Show More ResponsesOUT = (A NAND (B NAND 1)) or out = (A NAND (B NAND B)) like what anonymous said. One or more comments have been removed. Please see our Community Guidelines or Terms of Service for more information.

### Senior Hardware Verification Engineer at NVIDIA was asked...

Jan 29, 2010
 There are 5 bowls with 100 candies each. In 4 bowls, all of the candies are 10 grams each. In 1 bowl, all the candies are 9 grams each. Using a digital scale, how can you determine which bowl has the 9 gram candies by using only 1 weighing?2 AnswersTake 1 candy from bowl 1, 2 candies from bowl 2, 3 candies from bowl 3, and 4 candies from bowl; and weight them on the digital scale. If the total weight is 100 grams, the 9 gram candies are in bowl 5. If the total weight is 99 grams, the 9 gram candies are in bowl 1. If the total weight is 98 grams, the 9 gram candies are in bowl 2. If the total weight is 97 grams, the 9 gram candies are in bowl 3. If the total weight is 96 grams, the 9 gram candies are in bowl 4.if weighing machine can weigh the bowls: Put 2 bowls on each side, if they weigh equal then last bowl has candies with 9 grams. If the bowl weigh different then weigh the 2 bowls with lower weight and find the lowest weight bowl.

### Senior Hardware Engineer at Carnegie Technologies was asked...

Mar 6, 2019
 What is a time domain test instrument and what is a frequency domain instrument? I've never heard of these terma before.2 AnswersOscilloscope. (Maybe I should be interviewing you?)Oscope and Spectrum Analyzer :)

### Senior Hardware Engineer at Apple was asked...

Mar 5, 2012
 Not the most difficult question but I found this question interesting. Write a piece of code that allows you to detect if the machine you are running the program is little Endian or big Endian memory structure. 2 AnswersTo answer this question, you need to know about the union in C. 1) declare union { unsigned long ul; unsigned char tab } un; 2) then: un.ul=0x12345678; for(i=0; i<4; i++) printf("%x ",un.tab[i]);Much easier than that: inline int isLE() { int v = 1; //stored in host order char *p = (char *)&v; //can access addresses &p, ..., &p //LS byte stored at lower address in memory => LE return p; } I'm sure there's a more efficient way, but that's the best I know.

### Senior Hardware Engineer at Microsoft was asked...

Oct 4, 2019
 Non-trivial sender-receiver type of coding problem.2 AnswersYou need to write an FSM. For whatever they ask!Can you tell more about hour long coding interview? More detail on coding problem would help. Thank you!

### Senior Hardware Engineer at STMicroelectronics was asked...

Dec 12, 2009
 How many ping pong balls fit in a 7472 Answersabout 22 million in the main cabin depending on the installed options.The exact same number as the number of angels on the head of a pin. Go figure.

### Senior Hardware Development Engineer at Aerotek was asked...

Dec 27, 2016
 Do you have firmware development experience.1 Answeryes

### Senior Hardware Engineer at Oracle was asked...

Mar 22, 2012
 Parallel Computer architecture, -Gave the MP structure and then asked How would you maintain coherency 1 AnswerI had to tweak the directory based protocol
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