presence detect
Parallel Presence Detect
PPD
Serial Presence Detect
SPD
A means of identifying a memory chip to the
memory controller logic. The original scheme, Parallel
Presence Detect (PPD) used a separate pin for each bit of
information. The limited number of pins available only gave
the density and the speed of the chips. To pass more
information, the Serial Presence Detect (SPD) scheme was
introduced, storing the information in serial EEPROM with
one pin to enable it and one for data.
(2012-06-25)
|