Serial port Yost standard combines DSR and DCD. Some serial ports on motherboards or add-in cards provide jumpers that select whether pin 1 of the DE-9 connector connects to DCD or a power supply voltage, and whether pin 9 of the DE-9 connector connects to RI or a power supply voltage. The power supply voltage can be +5V, +12V, +9V, or ground. (Selection varies by vendor.) The power is intended for use by point-of-sale equipment. Makers include Dell, HP, and others (This is not an official standard.) Operating systems usually create symbolic names for the serial ports of a computer, rather than
Parallel communication is the significant reduction in the size, the complexity of the connectors, and the associated costs. Designers of devices such as smartphones benefit from the development of connectors/ports that are small, durable, and still provide adequate performance. On the other hand, there has been a resurgence of parallel data links in RF communication. Rather than transmitting one bit at a time (as in Morse code and BPSK), well-known techniques such as PSM, PAM, and Multiple-input multiple-output communication send a few bits in parallel. (Each such group of bits is called a "symbol"). Such techniques can be extended to send an