The function of a disk is to hold data onto which is on the computer. You can get internal hard drives which are already in the computer and the second type of hard drive is external which is like a peripherals which you can add of on.
Floppy Disk and Zip Disk
A floppy disk can only hold a certain amount of memory just 1.44M and it is used to transfer data. It looks like a chip as large as a phone. A zip disk is large floppy disks that can store more data. And you need a zip file to open the data on the floppy.
Primary Memory
Primary Memory is memory that is internal in the computer and it can be found on the motherboard of the computer which is the heart of the computer. An example of Primary Memory is the RAM and the ROM.
Tertiary Memory
It is the next level of memory that is in a computer and this the spare spaces that is on the computer and it can be used and it.
Flash Memory Cards
Flash memory card come in all sizes that can hold data up to 64GB. You can use them as a USB and also as a memory card that fits most into most mobiles phones. They are small that can fit into adapters.
USB Flash Drive
Portable memory card that plugs into computers usb ports and functions as a portable hard drive. USB flash drives are touted as being easy-to-use as they are small enough to be carried in a pocket and can plug into any computer with a USB drive. They come in all sizes that can be used.
Secondary Memory
Secondary memory is the slowest and cheapest form of memory that you can find on a CPU. It cannot be used to process directly by the Central Processing Unit. It needs to be copied into primary storage. Its memory that is external for example IPODs, USB and other external Devices.