Digital Electronics - Digital Concepts - Discussion

In hard drive, the data are stored in analog form are digital form?

The digital signals comprised of 1s and 0s organised in the form of groups called words (eg:1001010101010000-16bit word). Digital words that represent numbers, music, word documents are used by internal circuitary of mp3players, calculators, pc. For eg how DAC is used in mp3 player. Music stored in digital format convert it into analog format in headset. (input-binary (1111) 2 to decimal form (15) 10.

I cant understand the que correctly.

In this que, the information stored in CD is in digital form. DAC converts this information into usable form.

It's not necessarily audio cd. So not clear.

The digital information can be stored in various media other than audio CD's. When you need an analog output i.e. an output that is not expressed in 0's & 1's, you need something that converts digital input to analog data. Hence, DAC is used. Option A is at the most, the most logical option, not necessarily the correct one.

DAC converts the digital pulses into continuous (analog) form.

There are two basic type of converters, digital-to-analog (DACs or D/As) and analog-todigital
(ADCs or A/Ds). Their purpose is fairly straightforward. In the case of DACs,
they output an analog voltage that is a proportion of a reference voltage, the proportion
based on the digital word applied. In the case of the ADC, a digital representation of the
analog voltage that is applied to the ADCs input is outputted, the representation
proportional to a reference voltage.

DAC is used to convert discrete form to analog form.