Yes, it is counter intuitive why serial interface is faster than a parallel interface. The answer is "bit skew". With today's speeds, the speed of light delay through a cable can be longer than the time between the bits you are sending. It's odd to think that there can be two bits with different values inside the same short length of coper wire.
The problem is that if the cable is bent or otherwise not perfect some wires might be slower than other wires so you have to wait at the receiving end for al the bits to get there. You can't know how slow the slowest wire it so you have to wait for the worse case. With serial I can put the next bit into the wire BEFORE the previous bit has reached the end of the wire. The speed of light is slow. In one nanosecond a bit only moves one foot. A nanosecond is only 1GHz. If I send at 4GHZ, the bits are only a few inches apart in the cable. In today's digital world cables are transmutation lines with significant delays. Yo just can't send parallel data down a cable where the delay is much, longer then the pace between bits. Still of course we'd like to send more then one bit at a time. Obviously we can go faster by sending 16 bits at once. Yes. They do that now. Looks at PCIe. It is a 16 channel serial bus. Basically 16 serial interfaces. -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
