Compact Flash cards, which are portable storage devices, were introduced in 1994 by SanDisk as an alternative to hard drive storage for laptops and consumer network devices. The cards have different physical types, and card specifications have changed over the years as the original technology was continuously updated to include new features and capacities. The current specification for Compact Flash cards is CF 5.0.
CF Type I
The CF Type I card is different from the others primarily in size. The CF Type I is 1.7 inches long by 1.4 inches wide by 0.13 inch thick. CF Type I and Type II cards both use the same 50-pin interface. A Type I card will fit into a Type II card slot, but the Type II card will not fit into a Type I slot. This allowed backward compatibility for users with CF Type I cards purchasing laptops and computers fitted with the newer CF Type II card slot. The majority of Compact Flash cards on the market are CF Type I cards.
CF Type 2
The CF Type II card is 1.7 inches long by 1.4 inches wide by 0.13 inch thick. Both the CF Type I and Type II card support dual voltages, 3.3v and 5v. Manufacturers can use either voltage specification in either card type. Most of the CF cards on the market are CF Type I, although a few CF Type II cards are still manufactured Most of these are micro-drives, which are miniature hard drives.
CF Type I/O
The CF Type I/O card can be either a Type I or Type II Compact Flash card and allows for the addition of various other functional devices to the storage function. These can include Wi-Fi networking, Ethernet networking, Bluetooth wireless, USB ports, laser scanners and others. The majority of CF Type I/O cards are built on the technology that the CF Type I card uses. These CF cards use the same voltage and interface standards as the Type I and Type II cards.
CF 5.0 Features and Specifications
The CF specification is the current state of the art for Compact Flash technology. The most recent specification is the CF 5.0, which adds several features to the CF 4.1 specification and is based on the Parallel ATA (PATA) interface. This adds greatly increased storage capacity and speed to memory function. Capacities of greater than 137 GB are now possible with more efficient data transfer of up to 32 GB per transfer versus 128 MB for the previous specification. The new specification also adds 48-bit memory addressing, which allows for greater capacity and access efficiency. The new specifications apply to all Compact Flash card types in development.