Interview question

sparky64 · Mar 9, 2004

At a recent interview, i was asked why data is transmitted using hexadecimal values.
I didn't know the answer, and the interviewer never expanded on the question.

Can anyone answer the above question, as its been bugging me ever since.

Cheers
Sparky

PS I didn't get the job!!

Sliver · Mar 9, 2004

guess

Sparky,

I assume you are a regular electrician type? (like myself)

I would think that data is alway transmitted in binary but can be displayed in many ways Hex being one. Hex was used because it was easier to display on a 7 segment display than a long string of 1s and 0s yet could be more easily converted to binary than decimal values. But I'm sure there are going to be some more definitive responses from this crew.

Brian

elevmike · Mar 9, 2004

Data on a bus, be it serial or parelell is transmited in binaary. Sliver has the right idea.

Hex is a differnt, more effiectnt method of displaying Binary data.

For instance each hex value (0-9,A-F) usually contains the value for 4 bits of binary data.

0 = 0000
1 = 0001
2 = 0010

A = bin 10 = 1100
F = bin 16 = 1111

FFFF = 65536 = 1111111111111111

The data is displayed more efficently, and easer to be understood etc..when programming in low level languages such as assembly, PLCs, etc. Just imagine the number of keystokes it would take otherwise.

As far as the bus, or board level components go, its all coming and going in binary.

Mike.

bernie_carlton · Mar 9, 2004

Could the interviewer have been referring to the ASCII versus Hex modes for Modbus communication?

sparky64 · Mar 11, 2004

Thanks for the replies

Cheers
Sparky

AndrewB · Mar 12, 2004

my understanding was this came about when everything was 8 bit.

The reasoning for hex was any number from 0 to 255 could be displayed using only 2 numbers.

ie. 11111111 in binary = 255 in decimal = FF in hex

hdblue · Mar 15, 2011

AndrewB said:
my understanding was this came about when everything was 8 bit.

The reasoning for hex was any number from 0 to 255 could be displayed using only 2 numbers.

ie. 11111111 in binary = 255 in decimal = FF in hex

Hi,

I agreed with you. It help me to think about my ideals.

Pls try to keep posting. Tks and best regards.

daba · Mar 16, 2011

elevmike said:
....For instance each hex value (0-9,A-F) usually contains the value for 4 bits of binary data.

0 = 0000
1 = 0001
2 = 0010

A = bin 10 = 1100
F = bin 16 = 1111

FFFF = 65536 = 1111111111111111

Couple of minor errors here, Mike.

A = dec 10 = 1010

FFFF = 65535 = 1111111111111111

just so that no-one gets misled...

rdrast · Mar 16, 2011

daba said:
Couple of minor errors here, Mike.

A = dec 10 = 1010

FFFF = 65535 = 1111111111111111

just so that no-one gets misled...

That, and 1111b = 15 dec = F hex.

But as for the original question, the only possible answer is "Because that manufacturer decided to do it that way".

Not all data is transmitted as hex period. Digitally encoded information may be transmitted over a serial or parallel link in virtually any manner of encoding.

Then there is also analog transmission, or pulse-coded modulation, or frequency.

That is a typical worthless interview question dredged up by some mouthbreathing seatwarmer in a human-resources department in a useless attempt to filter candidates headed towards a position the interviewer doesn't have the first clue about.

Rube · Mar 16, 2011

I hope he's gotten a job in the last seven years!!

Steve Etter · Mar 16, 2011

rdrast said:
...That is a typical worthless interview question dredged up by some mouthbreathing seatwarmer in a human-resources department in a useless attempt to filter candidates headed towards a position the interviewer doesn't have the first clue about.

Feel strongly about this, Bob?

Steve

daba · Mar 16, 2011

I went back in to edit it to 15 - but my ISP ditched me (yet again!).

Top marks for .... "That is a typical worthless interview question dredged up by some mouthbreathing seatwarmer in a human-resources department in a useless attempt to filter candidates headed towards a position the interviewer doesn't have the first clue about."

Steve Bailey · Mar 16, 2011

The interviewer was the same person who put together the curriculum for the HNC exam. Thus the "Unitary, Modular, Rack-Mounted" question.

uptown47 · Mar 16, 2011

rdrast said:
That is a typical worthless interview question dredged up by some mouthbreathing seatwarmer in a human-resources department in a useless attempt to filter candidates headed towards a position the interviewer doesn't have the first clue about.

I too would like to salute you for this exquisitely succint quote. Best laugh I've had all week

(in answer to the original question - allbeit, asked some 7 years ago - I always thought that we used to use Octal a lot because computers dealt in 8 bits and then when we progressed to 16 bit computing, Hex - base 16 - became the best way of representing the data)...

yam785 · Mar 16, 2011

Some interviewers make you wonder.

I have been in some interviews, where it was not only management, but sometimes also an engineer or other automation person. Sometimes these people will bring up a question, which is something they just learned, or just used on a project, and are more interested in impressing management, then actually asking a pertinent question.

I was once asked if I understood 'Optic Logic'? I think he meant how optics control conveyors. My answer was 'Do you mean the difference between wiring and input cards for PNP and NPN'? I got a blank stare from him, as he had no clue what I was talking about.

Sometimes you have to interview the interviewers.

Interview question

sparky64

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