Before microSD, SD, MMC and Compact Flash the removable flash standard was PCMCIA cards. All laptops came equipment with a PCMCIA slot to accept a PCMCIA ATA type II card.
Still used today by the military and industrial equipment PCMCIA cards are available in different builds, know the difference before you buy.
Like other types of flash memory, PCMCIA cards are available in both MLC and SLC chipsets. those unfamiliar with these standards, the most may be familiar is MLC (Multi Level Cell). Cards built using this method are typically consumer grade and hold a temperature rating of 0C to +70C.
PCMCIA Cards built with SLC chipset are rated at -40C to +85C and typically include some type of error correction and or wear leveling technology as well.
So depending on your environment you will want to choose the appropriate card for your equipment’s needs.
In addition to the temperature and wear leveling technology PCMCIA cards are available in a plastic and metal housing. In a majority of the cases the plastic housings are more affordable and readily available. The metal housing cards have a longer lead time and are more rigid. The specifications such as temperature, vibration and shock are rated the same for both housings.
One additional option that is not usually mentioned are the coatings that may be applied to the components on the cards. One type is acrylic and the other is silicon based. Both are used when additional vibration and shock ratings are needed in order for the cards to meet certain specifications. Keep in mind that when ordering these cards you will void the warranty as no warranty repairs can be performed on the cards after these coatings have been applied.