The HMX-Q20 supports an SDXC memory card which is better than the SD memory card supported by most video cameras of a comparable spec and age to it. In addition, this video camera supports an SDHC memory card. SDXC cards are SD cards but with a much higher capacity and faster processing speeds. They have a maximum capacity of 2TB (Terabytes).
An SDXC memory card is in fact the best supported memory card type amongst all camcorders that have been available for a similar time to the HMX-Q20.
Amongst similar types of camcorder the worst supported memory card type is MicroSDXC.
SDHC cards are DS cards with a higher capacity of up to 32GB.