ISBN: | 978-5-5134-9894-0 |
High Quality Content by WIKIPEDIA articles! Serial presence detect (SPD) refers to a standardized way to automatically access information about a computer memory module. Earlier 72-pin SIMMs included 5 pins which provided 5 bits of parallel presence detect (PPD) data, but the 168-pin DIMM standard changed to a serial presence detect to encode much more information.