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I have a scheme that in it I have D/A which is digital to analog converter, and A/D but what is it P/S and S/P ?

And what is it used for?

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1 Answers1

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"Parallel to Serial" and "Serial to Parallel" respectively.

Serial communication offers several advantages, that are usually were (in the past, when frequencies were lower) paid by slower speed:

  1. Less wires (first and obvious, and influencing the others);
  2. Avoids the problem of sychronizing the signals, that in the parallel connection can be skewed;
  3. Generally more robust.

As Kevin said, serial connections are getting faster and faster, and serial protocols like PCIe and SATA have taken the place of parallel BUSs. Mostly this is due to the fact that the limiting factor for parallel connections is the capability to synchronize the signals over the various lines, while serial protocols haven't this problem.

clabacchio
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    usually paid by slower speed - When you use a dedicated serializer/deserializer IC (Which I've seen called a "SERDES", but never a S/P converter) that uses a robust and fast serial communication mechanism like a line encoding and differential signalling, you can often transmit faster than you could using a parallel cable due to timing skew. That's one of the reasons why most modern high-speed protocols are serial (USB, Ethernet, SATA, Firewire, PCIe) and parallel protocols (DB-25 parallel ports, ATA, SCSI, PCI) have fallen out of style. – Kevin Vermeer Mar 03 '12 at 17:57
  • @KevinVermeer But it seems that, while being serial these protocols they have multiple lines, which is more similar to parallel bus in term of wiring. – clabacchio Mar 03 '12 at 19:04
  • No, they're serial, regardless of whether the signals are sent via a single-sided voltage returned on a ground or by a differential signal on a twisted pair. Some (like multi-channel PCIe and USB 3.0) use multiple serial links which are resynchronized at a higher level, but none require readout of multiple signals at the same time. – Kevin Vermeer Mar 03 '12 at 19:13
  • @KevinVermeer I agree; what I was saying is that PCIe has nearly the same number of wires than PCI, so in that way it breaks the point no. 1 – clabacchio Mar 03 '12 at 19:16