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 automatically negotiated. Often if the settings are entered incorrectly the connection will not be dropped; however, any data sent will be received on the other end as nonsense. Serial ports use two-level (binary) signaling, so the data rate in bits per second is equal to the symbol rate in baud. A standard series of rates is based on multiples of the rates for electromechanical teleprinters; some serial ports allow many arbitrary rates to be selected. The port speed and device speed must match. The capability to set a bit rate does not imply that a working connection will result. Not