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
38th parallel structures piqued by observations of comet Shoemaker–Levy 9 impacting on Jupiter in 1994. It is estimated, however, that the likelihood of such an event on Earth is vanishingly small because the Earth's weaker gravitational field is much less able than Jupiter's to pull a speeding object close enough to be torn apart by tidal forces. However, evidence of serial impacts on the Moon can be seen in several chains of craters. Notes Sources 38th parallel structures The 38th parallel structures, also known as the 38th parallel lineament, are a series of circular depressions or deformations stretching 700 km (435 mi) across