The HDC-SD90 supports an SDXC memory card which is better than the SD memory card supported by most video cameras that were released around the same time as 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 actually the best supported memory card type amongst all video cameras of this spec and age.
Amongst similar types of video camera the worst supported memory card type is MicroSDXC.
SDHC cards are DS cards with a higher capacity of up to 32GB.