Chapter 2 : 2.5.3 Memory 2017/2018 Faizah Ma'arof

1. Computer System
2.5.3 Memory
At the end of this topic, students
should be able to:
a)Describe the function of the memory
b)Differentiate between volatile and nonvolatile
memory
c)Identify different types of memory
1
Chapter
PDT - 2017/2018

2. Memory
3
●Memory consists of electronic components that
store instructions waiting to be executed by the
processor, data needed those instructions, and the
results of the processing data
●Each location in memory has an address
●Memory size is measured in KB (Kilobyte), MB
(Megabyte), Gb (Gigabyte) or TB (Terabyte). (* refer
to 2.1.3 storage capacity)
2

3. Page 225 Discovering Computers 2012: Chapter 4 4
Figure 4-20
RAM chips usually reside on a
memory module and are
inserted into memory slots
3

4. Types of memory
Memory
NonvolatileVolatile
5
4

5. Volatile memory
• When the computer’s power is turned off,
volatile
Volatile
RAM is
memory loses its contents.
memory is temporary.•
• the most common type of volatile
memory
6
5

6. Volatile memory : RAM
• RAM chips usually reside on a memory module
and are inserted into memory slot
• The amount of RAM necessary in a computer often
depends on the types of software you plan to use
9
6

7. Three basic types of RAM
Discovering Computers 2012: Chapter 4 10
DRAM
(Dynamic RAM )
SRAM
(Static RAM )
MRAM
(Magnetoresistive
RAM)
• Chips must be re-
energized constantly or
they lose their contents.
• Chips are faster and
more reliable than any
variation of DRAM chips.
• A newer type of RAM,
called magnetoresistive
RAM (MRAM pronounced
EM-ram), stores data using
magnetic charges instead
of electrical charges
7

8. Nonvolatile Memory
● Nonvolatile memory does not lose its
contents
● when power is removed from the computer.
● Nonvolatile memory is permanent and
cannot modified.
● Eg : ROM
7
8

9. Nonvolatile Memory : ROM
• Read-only memory (ROM) refers to memory chips
storing permanent data and instructions.
• The data on most ROM chips cannot be modified.
11
9

10. 8
Volatile (RAM) Nonvolatile (ROM)
Temporary : loses its contents when
the power is turned off
Permanently : Does not lose contents
when the power turned off
Can be read from and written to by the
processor and other device
Data is prerecord for read only and
cannot be modified or removed
Hold data or programs that are
currently being used by the processor
Contain a small startup program
(BIOS) which is used to boot the
computer
RAM chip usually reside on a memory
module and are inserted onto the
memory slot
Exist as a chip on the motherboard
Differences Between Volatile and
Nonvolatile
10

11. Types of ROM
12
PROM
(Programmable Read-
Only Memory)
EPROM (Erasable
Read-Only Memory)
EEPROM (Electrically
Erasable
Programmable Read-
Only Memory)
• Is a blank ROM chip
on which a programmer
can write permanently.
● These chips can be
erased and rewritten a
number of times.
• Allows a programmer
to erase the microcode
with an electric signal
11