Sony PlayStation Portable PSP-1003 K - Manual (Page 110)

110 Compatible media
There are two sizes of Memory Stick™: the standard size and the smaller size.
The PSP™ system is compatible with Memory Stick Duo™, the smaller sized
type. The standard-size Memory Stick™ cannot be used with the system.
Memory Stick Duo Adaptor
The Memory Stick Duo Adaptor (MSAC-M2: a Sony product sold separately)
allows a Memory Stick Duo™ to be used with devices that take a standard-size
Memory Stick™.
MagicGate™-compatible Memory Stick Duo™
The MagicGate™-compatible Memory Stick Duo™ has been designed with an
indented area (see figure A) to allow it to be differentiated by touch from the
standard Memory Stick Duo™.
MagicGate
is a term of copyright-protection technology developed by
Sony Corporation.
Parallel data transfer (high-speed data transfer)
Parallel data transfer is a high-speed data transfer technology that allows
multiple data input/output connectors on the Memory Stick™ to be used at the
same time (parallel interface).
Memory Stick™
does not guarantee compatibility with other products
bearing the "MagicGate" trademark.