main memory and secondary memory

[jethney]

o The primary memory itself is implemented by two types of memory
technologies. The first is called Random AccessMemory (RAM) and the
other is read only memory (ROM). Amore appropriate name for RAM is RWM
(Read Write Memory), the CPU can write and read information from any
primary memory location implemented using RAM. The other part of
primary memory is implemented usingROM which stands for Read Only
Memory.
Primary memory is much faster and also it is more cost effective. But
the secondary memory is much slower and also less costly. It stores
the data permanently unless it is erased. The secondary memory is
usually available in the form of floppy disk storage media, hard disk,
CD, DVD, Pen drive (i.e. Massstorage devices), memory chips. A 5
and1/4 inch floppydisk typically stores 1.44 mb of data. The data on
the floppy disk is organized in terms of tracks and sectors. Hard disk
can have large capacity something like 80-300 GB's or higher. Hard
disk itself is made up of, large number of platters. Hard disk is
usually much faster compared to floppy disk. CD can store up to 750 mb
of data. Information on CDROM is organized in terms ofa spiral track.
A DVD is digital Versatile Disk and canstore 4.6 Gigabyte of
information. All these CD diskare usually write ones and read many
times (if the disk is not multisession and re writable). So are the
DVDs.