Serial presence detect use of SIMMs with "parallel" presence detect (more commonly called simply "presence detect" or PD). Some of this equipment uses non-standard PD coding, IBM computers and Hewlett-Packard LaserJet and other printers in particular. Serial presence detect In computing, serial presence detect (SPD) is a standardized way to automatically access information about a memory module. Earlier 72-pin SIMMs included five pins that provided five bits of "parallel presence detect" (PPD) data, but the 168-pin DIMM standard changed to a serial presence detect to encode much more information. When an ordinary modern computer is turned on, it starts by doing a power-on
Serial port all bit rates are possible with all serial ports. Some special-purpose protocols such as MIDI for musical instrument control, use serial data rates other than the teleprinter series. Some serial port systems can automatically detect the bit rate. The speed includes bits for framing (stop bits, parity, etc.) and so the effective data rate is lower than the bit transmission rate. For example, with 8-N-1 character framing only 80% of the bits are available for data (for every eight bits of data, two more framing bits are sent). Bit rates commonly supported include 75, 110, 300, 1200, 2400, 4800, 9600,