As far as my understanding goes, parallel data connections are faster than serial at the same frequency. However, when you increase the frequency in parallel you start getting bits 'cross-talking' and getting transferred onto the next bus. Serial however, since it's only a single bus line, can have the frequency increased to make it faster than parallel without a problem. Also, surely parallel is more expensive as it uses more lines.
So my question is, what actually is the benefit of using a parallel data connection over a serial one? Are there any? If not, why do we still use parallel connections?
Answer
Parallel bus allows you to send more data than serial at the same frequency. That's it. This is why serial is more popular now than parallel. In the past it was difficult to have very high frequencies, so parallel was better.
For example:
- SATA1 gets 150MB/s and requires at least 1.5GHz frequency.
IDE gets 133MB/s and requires only 66MHs.
PCI-e x1 gets 250MB/s for 2.5GHz
- 64bit PCI (server standard) gets 266MB/s for 66MHz
In the past it would have been very expensive (if even possible) to have SATA or PCI-e interface with the extreme frequency requirements.
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