This document discusses different types of computer memory. It begins by introducing primary memory which includes RAM and ROM. It then describes different types of RAM like SRAM, DRAM, RDRAM and their structures. Next it covers different types of ROM like PROM, EPROM, and EEPROM. It also discusses the memory hierarchy and how cache memory improves performance. Finally, it summarizes different types of secondary storage like hard disk drives, their layout and various RAID configurations.

1. Memory
1.Rupol Ahmed-16103342
2. Md.Milon Sarker-161033
3.Shakil Ahmed-16103348
4. Saifullah Al Mamun-16103318
5.Abdullah Al Sabit-16103343
6.Joyanta Kumar Sarker-16103352

2. Did you know…
Memory :
Provides your working space (
e.g. the amount of RAM installed
in the computer)

3. MEMORY HIERARCHY
Magnetic
tapes
Magnetic
disks
I/O
processor
CPU
Main
memory
Cache
memory
Auxiliary memory
Register
Cache
Main Memory
Magnetic Disk
Magnetic Tape
Memory Hierarchy is to obtain the highest possible
access speed while minimizing the total cost of the memory system
Memory Hierarchy
LevelsofMemory
3

4. Memory
Primary
Memory
Ram
SRAM DRAM
SDRAM RDRAM
DDR
DDR DDR2
DDR3 DDR4
Rom
PROM EPROM
EEPROM
Secondary
Memory
Magnetic
Magnetic
Tape
Magnetic
Disk
Optical
CD DVD
Blue-Ray

5. Primary MEMORY
RAM and ROM Chips
Typical RAM chip
Typical ROM chip
Chip select 1
Chip select 2
Read
Write
7-bit address
CS1
CS2
RD
WR
AD 7
128 x 8
RAM
8-bit data bus
CS1 CS2 RD WR
0 0 x x
0 1 x x
1 0 0 0
1 0 0 1
1 0 1 x
1 1 x x
Memory function
Inhibit
Inhibit
Inhibit
Write
Read
Inhibit
State of data bus
High-impedence
High-impedence
High-impedence
Input data to RAM
Output data from RAM
High-impedence
Chip select 1
Chip select 2
9-bit address
CS1
CS2
AD 9
512 x 8
ROM
8-bit data bus
Main Memory55

6. RandomAccess Memory (RAM)
• Structure :
A set of memory chips, each of them
is an integrated circuit (IC) made of
millions of transistors and capacitors
• Volatile - their state is lost or reset
when power is removed from the
system.
• Usage :
Holds data/application programs
from input devices or storages

7. Types of RAM
Static Random Access Memory
(SRAM)
Dynamic Random Access
Memory (DRAM)
•
•
Semi conductor memory
Use flip-flop to store each bit
memory so does not need to
periodically refreshed
• Store each bit of memory in
capacitor in an integrated circuit
Real capacitors leak charge so
capacitors need to be refreshed
periodically
Simple structure ( 1 transistor and
1 capacitor per bit) so it has very
high density
DRAM requires the supporting
refresh circuitry.
of
be •
•
•
Faster and consumes low power
Expensive and have complex
structure (6 transistors) so not use
in high capacity applications
•

8. STATIC RAM Structure
8

9. Typical 16 Mb DRAM (4M x 4)
9

10. 10

11. RAMBUS DRAM Structure
11

12. Read only memory (ROM)
• Has contents which are fixed when
the chip is manufactured
• Holds the bootstrap loader part of
the operating system
• Retains its data when the computer
is switched off

13. Types of ROM
Programmable ROM (PROM)-
Empty of data when the chip is
manufactured, can be
programmed by the user. Once
programmed the data cannot be
erased.
Erasable PROM (EPROM)-
Like PROM only the chip can be
removed from the computer and
the program erased and another
stored in its place using
ultraviolet light.
Electrically EPROM (EEPROM)
-
Like EPROM but electricity is
used to erase and reprogram

14. Cache memory
•
•
Faster and expensive than RAM
It improves the computer’s
performance
Processor can use it to store
frequently accessed data and
program instructions
It is two types :
- L1 : primary cache (inside the
processor)
- L2 : secondary cache (in the
motherboard or near the
microprocessor)
•
•

15. Magnetic storage devices
Hard disk drive (HDD)
• First introduced in 1956
Became dominant in the 1960s
Capacity keeps increasing
Max. capacity: 4 TB
(as of 2013)
• Continuously improved.
• Maintained an important position
of modern servers and PCs.

17. 17
Disk Data Layout

18. 18
RAID 0

19. 19
RAID 1

20. 20
RAID 5

21. 21
RAID 10

22. You didn’t hear that?
Thank you