The document discusses different types of computer memory and storage. It describes the computer memory as temporary storage that holds data and instructions for the CPU. It distinguishes between read-only memory (ROM) which permanently stores important programs, and random access memory (RAM) which is used as working memory and can be written to. Secondary storage such as hard drives and optical disks are slower than primary memory but can store larger amounts of data permanently. The document traces the history of computer data storage from early technologies like punched cards, magnetic drums, floppy disks, to modern hard drives and optical disks.

1. Computer memory
Presented by: Mark Anthony Ibañez

2.  The computer memory is
a temporary storage area. It holds
the data and instructions that the Central
Processing Unit (CPU) needs. Before
a program can be run, the program
is loaded from some storage medium into
the memory. This allows the CPU direct
access to the program. Memory is a need
for any computer.

3.  Read only memory
(ROM) is the permanent memory which is used
to store important control programs and systems
software to perform a variety of functions, such
as booting up or starting up programs. ROM is non-
volatile. That means the contents are not lost when
the power is switched off. Its contents are written
at the time of manufacture, but in modern (2012)
computers may be changed using special software.
Types of Primary memory

4.  Random access memory
(RAM) is used as the working memory of
a computer system. It stores input data,
intermediate results, programs, and other
information temporarily. It can be read and
written. It is usually volatile, that is all data
will be lost when the power is turned off. In
most cases it is loaded again from hard
disk which is used as data storage.

5. Difference between RAM & ROM
RAM ROM
VOLATILE MEMORY NON VOLATILE
Data in ram is not permanently
written when power off, data deleted
Permanently, not erased
Ram: DRAM & SRAM ROM: PROM & EPROM
It requires flow of electricity to
retain data
It does not requires electricity to
retain data
Ram is the memory available for the
operating system programs and
process to use when the computer is
running
Rom is the memory that comes with
your computer that is pre-written to
hold the instructions for booting up
the computer

6. What is Secondary memory
 Secondary memory (or secondary storage) is the slowest
and cheapest form of memory. It cannot be processed
directly by the CPU. It must first be copied into primary
storage (also known as RAM).
Secondary memory devices include magnetic disks
like hard drives and floppy disks ; optical disks such
as CDs and CDROMs ; and magnetic tapes, which were
the first forms of secondary memory.

7. The history of computer data
storage, in pictures

8. The Selectron tube
The Selectron tube had a capacity of 256 to 4096 bits (32 to
512 bytes). The 4096-bit Selectron was 10 inches long and 3
inches wide. Originally developed in 1946, the memory
storage device proved expensive and suffered from
production problems, so it never became a success.

9. Punch cards
Early computers often used punch cards for input both of
programs and data. Punch cards were in common use until the
mid-1970s. It should be noted that the use of punch cards
predates computers. They were used as early as 1725 in the
textile industry (for controlling mechanized textile looms).

10. Punched tape
Same as with punch cards, punched tape was originally
pioneered by the textile industry for use with mechanized
looms. For computers, punch tape could be used for data
input but also as a medium to output data. Each row on the
tape represented one character.

11. Magnetic drum memory
Invented all the way back in 1932 (in Austria), it was widely
used in the 1950s and 60s as the main working memory of
computers. In the mid-1950s, magnetic drum memory had a
capacity of around 10 kB.

12. The hard disk drive
The first hard disk drive was the IBM Model 350 Disk File that came with
the IBM 305 RAMAC computer in 1956. It had 50 24-inch discs with a total
storage capacity of 5 million characters (just under 5 MB).

13. The Laserdisc
We mention it here mainly because it was the precursor to the CD-ROM and other
optical storage solutions. It was mainly used for movies. The first commercially
available laserdisc system was available on the market late in 1978 (then called
Laser Videodisc and the more funkily branded DiscoVision) and were 11.81 inches
(30 cm) in diameter. The discs could have up to 60 minutes of audio/video on
each side. The first laserdiscs had entirely analog content. The basic technology
behind laserdiscs was invented all the way back in 1958.

14. The floppy disc
The diskette, or floppy disk (named so because they were flexible), was
invented by IBM and in common use from the mid-1970s to the late
1990s. The first floppy disks were 8 inches, and later in came 5.25 and
3.5-inch formats. The first floppy disk, introduced in 1971, had a
capacity of 79.7 kB, and was read-only. A read-write version came a year
later.