To select input and output devices, first find out what the customer wants. Next, select the hardware and software by researching the Internet for possible solutions. After you determine which input or output device the customer needs, you must determine how to connect it to the computer. Figure 1 shows common input and output connectors.
Technicians should have a good understanding of several types of interfaces:
- FireWire (IEEE 1394) - Transfers data at 100, 200, or 400 Mb/s and IEEE 1394b at 800 Mb/s.
- Parallel (IEEE 1284) - Transfers data at a maximum speed of 3 MB/s.
- Serial (RS-232) - Early versions were limited to 20 Kb/s, but newer versions can reach transfer rates of 1.5 Mb/s.
- SCSI (Ultra-320 SCSI) - Connects as many as 15 devices with a transfer rate of 320 MB/s.
The USB interface is widespread and used with many different devices. Figure 2 shows the common USB 1.1 and 2.0 plugs and connectors. Figure 3 shows common USB 3.0 plugs and connectors.
The SATA interface has become common in recent years. SATA is replacing IDE and EIDE as the standard interface for hard drives and SSDs. SATA cables are easier to connect because they only have two ends, drives do not need to be jumpered, and eSATA drives can be hot-plugged if the motherboard supports hot-plugging. Figure 4 compares PATA and SATA speeds.