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I am doing a pass paper question of my exam and I got following question. What is the maximum amount of data that can be written within 1 second to a 52X CD-R using a CD Writer with a write speed of 24X ?

When I calculate this I got 31.7.

I have two issues. Is this MB or MiB? I searched several calculation methods on google. Those provided me different values. If possible please provide me a correct algorithm to calculate this.

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Well, 1x is 150KB/s. So 52x is 7800KB/s and 48x is 7200KB/s. –  Dan D. Mar 16 '13 at 10:00
    
Thanks.The strange things is the given answers are in MB and Mib formats and more than 24 by it's value. –  Prasad Rajapaksha Mar 16 '13 at 10:03
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1 Answer 1

up vote 3 down vote accepted

Single speed CDROMs read up to 75 sectors per second. A data sector on a CDROM is 2048 bytes. So read speed for an "1x CDROM" is 150 KiB/sec. I bolded 'up to' since not all drives reach this speed. Many drives from that area managed 130-140 KiB/sec.

Regardless, 150KB/sec is the current accepted speed for an 1x CDROM.

A CDROM is called 2x if it can read up to 300 KiB/sec (2x150)
A CDROM is called 4x if it can read up to 600 KiB/sec (4x150)
...
24 speed is 24x150 KiB/sec is 3600 KiB/sec.


That assumes that:

  • The system is generating data fast enough so you actually have something to write.
  • That the writer is capable of that speed (well, that is a given in your question).
  • That the medium allow writing at that speed. (Your medium allows up to 52x writing).
  • That the drive is already spun up.
  • That the drive is ready to write actual data. E.g. no need to start with a lead-in.

Is this MB or MiB?

My answer is in KiB since a data sector on a CDROM is 2048 bytes, or 2 KiB.

If you want it in MB:  3600/1000 -> 3.6 MB/sec
If you want it in MiB: 3600/1024 -> 3.51 MiB/sec

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