Transmission speeds can vary greatly, depending on the sender andreceiver. One bit at a time is transferred to the device. Serial transfers have the following characteristics: Serial ATA (SATA) host adapters and drives IEEE-1394 ( FireWire, i.Link) ports and devices Modems (which can be internal devices or can connect to serial or USBports) USB (Universal Serial Bus) 1.1 and 2.0 ports and devices Serial (also called RS-232 or COM) ports and devices The following ports and devices in the computer use serial transfers:

This sounds like a recipe for slowdowns, but it alldepends on how fast the speed limit is on the 'data highway.' Serial TransfersĪ serial transfer uses a single 'lane' in the computer forinformation transfers. Short maximum lengths for parallel, ATA/IDE, and SCSI cablesĭual-speed motherboards (running the CPU internally at much faster speedsthan the motherboard or memory)įortunately, there is a second way to transmit information: serialtransfers. This is referred to as signal skew (see Figure 3.7).įigure 3.7 Parallel cables that are too long can cause signal skew, allowing the parallel signals to become 'out of step' with each other.ĭifferences in voltage between wires or traces can cause jitter.Īs a result of these problems some compromises have had to be included incomputer and system design: Many wires or traces (wire-like connections on the motherboard orexpansion cards) are needed, leading to interference concerns and thick,expensive cables.Įxcessively long parallel cables or traces can cause data to arrive at different times. However, parallel transfers also have problems: Multiple bits of information are sent at the same time.Īt identical clock speeds, parallel transfers are faster than serialtransfers because more data is being transferred. RAM and interface cards (either via the CPU or directly withDMA) Parallel transfers takeplace between the following devices: Parallel transfers use multiple 'lanes' for data andprograms, and in keeping with the 8 bits = 1 byte nature of computerinformation, most parallel transfers use multiples of 8. These terms are used frequently, but if you're not familiar with the differences between them, check out Figure 3.6.įigure 3.6 Parallel data transfers move data 8 bits at a time, whereas serial data transfers move 1 bit at a time.

When you create data and print it,the CPU instructs the printer to output the data.īecause of the different types of devices that send and receive information, two major types of data transfers take place within a computer: parallel and serial. When you start a program, the CPU instructs thestorage device to load the program into RAM. The CPU is the centralpoint for most information.

Information flows through the computer in many ways. Learn More Buy Serial Versus Parallel Information Transfer Absolute Beginner's Guide to A+ Certification

Serial vs parallel port