The document provides an overview of various memory devices and their terminology. It defines common terms like MOS, flip-flop, SRAM, DRAM, ROM, EEPROM, and cache. SRAM uses an array of flip-flops to store data and is very fast but volatile. DRAM uses dynamic storage cells that must be regularly refreshed to prevent data loss, making it slower than SRAM but able to store more data. ROM is programmed during manufacturing and cannot be rewritten. EEPROM can be electrically erased and reprogrammed without removing it from a system.

1. Unit 1 Electronic Devices
Lesson 2 Memory Devices

2. 2023/1/25 2
Lesson 2 Memory Devices
• Backgrounds
• Text tour
• Language in use
– Vocabulary

3. 2023/1/25 3
• Terminology
– MOS, PMOS, NMOS, CMOS
– Flip-flop, Register
– SRAM, DRAM, ROM, EEPROM
– CAM
– Cache
– Ferroelectric
Backgrounds

4. 2023/1/25 4
Terminology

5. 2023/1/25 5
• MOS: Metal-oxide semiconductor
• PMOS: p-type Metal-oxide semiconductor
• NMOS: n-type Metal-oxide semiconductor
• CMOS: Complementary Metal-Oxide-Semiconductor
MOS, PMOS, NMOS, CMOS

6. 2023/1/25 6
MOS, PMOS, NMOS, CMOS

7. 2023/1/25 7
• A flip-flop is basically a bi-state circuit in which either a 0
or 1 state can resides. Because of its simplicity, the flip-
flop is extremely fast. As a basic element, the flip-flop is
used in digital circuits and ICs. A flip-flop will lose its
state when the supply voltage is removed. Therefore, it is
volatile.
Flip-flop, Register

8. 2023/1/25 8
• A register is a set of flip-flops in parallel. Typically a
register is 8, 16, 32 or 64 bits wide. Often a register is used
to hold data, address pointers etc. A register is volatile and
very fast just like the flip-flop.
Flip-flop, Register

9. 2023/1/25 9
• SRAM: Static Random Access Memory
• An SRAM is an array of addressable flip-flops. The
array can be configured as such that the data comes out
in single bit, 4-bit, 8bit and etc. format.
• SRAM is simple, fast and volatile just like the flip-flop,
its basic memory cell.
SRAM, DRAM, ROM, EEPROM

10. 2023/1/25 10
• DRAM：Dynamic Random Access Memory
• The word ´dynamic´ indicates that the data is not held
in a flip-flop but rather in a storage cell. The data in a
storage cell must be refreshed (read out and re-written)
regularly because of leakage.
SRAM, DRAM, ROM, EEPROM

11. 2023/1/25 11
• ROM: Read Only Memory
• ROMs are also called mask-ROMs or mask programmed
ROMs. This is because a ROM needs to be programmed
by setting its cells to either 0 or 1 at the time of
manufacture.
SRAM, DRAM, ROM, EEPROM

12. RAM & ROM
2023/1/25 12

13. 2023/1/25 13
• EEPROM：Electrically Erasable Programmable ROM
• This means that the chip can be programmed like an
EPROM, but can be erased electrically. As a result, no
UV source is required.
SRAM, DRAM, ROM, EEPROM

14. 2023/1/25 14
CAM is also known as "associative storage". It is a memory
chip in which each bit position can be compared. In CAM
chips, the content is compared in each bit cell, allowing for
very fast table lookups.
CAM: Content Addressable Memory

15. 2023/1/25 15
• The cache is a temporary storage area for frequently-
accessed or recently-accessed data. Having certain data
stored in a cache speeds up the operation of the
computer. There are two kinds of cache: internal (or
memory cache) and external (or disk cache). Internal
cache is built into the processor and external cache is on
the motherboard.
• When an item is called for, the computer first checks the
internal cache, then the external cache, and finally the
slower main storage.
Cache

16. How Cache Memory Works?
2023/1/25 16

17. 2023/1/25 17
• Ferroelectric is a phenomenon exhibited by certain
materials in which the material is polarized in one
direction or the other or reversed in direction by the
application of a positive or negative electric field of
magnitude greater than a certain amount.
Ferroelectric

18. 2023/1/25 18
Text tour
• Outline
– Overview (para.1, 2)
– Flip-flop (para.3)
– Register (para.4)
– SRAM (para.5,6,7)
– DRAM (para.8,9)
– ROM (para.10,11)
– EEPROM (para.12)

19. 2023/1/25 19
Text tour
Type Properties R/W Non-
volatile
Speed Cost
/bit
Flip-flop
One-bit register.
Usually used as
a basic building block
in digital circuits.
Yes No
Ultra
fast
Very
high
Register
Set of flip-flops
holding a byte,
word or long word.
Used in
complex chips
such as CPUs.
Yes No
Ultra
fast
Very
high

20. 2023/1/25 20
Text tour
Type Properties R/W Non-
volatile
Speed Cost
/bit
SRAM
Array of flip-flops that is
addressable. Used for
temporary storage of data
or cache.
Yes No
Very
fast
high
DRAM
Array of storage cells
which is addressable.
Used for main computing
data storage.
Yes No fast
Mode
rate

21. 2023/1/25 21
Text tour
Type Properties R/W Non-
volatile
Speed Cost
/bit
ROM
Array of
hard-wired cells
that is addressable.
Programming done
at time of
chip manufacture.
No Yes
Very
fast
low
E2PROM
Electrically erasable
programmable ROM.
Number of write
cycles is limited.
Yes Yes low high

22. 2023/1/25 22
• Vocabulary
– static，dynamic, approach, pattern,
hybrid , indicate
Language in use

23. 2023/1/25 23
Vocabulary

24. 2023/1/25 24
• Having no motion; being at rest; quiescent.
• Fixed; stationary.
• Of, relating to, or producing stationary charges; electrostatic.
• Of, relating to, or produced by random radio noise.
• Random noise, such as crackling in a receiver or specks on a television
screen, produced by atmospheric disturbance of the signal.
Static, dynamic in dictionary

25. 2023/1/25 25
• SRAM (Static Random Access Memory)
• DRAM (Dynamic Random Access Memory)
Static, dynamic in text

26. 2023/1/25 26
• static electricity
• static induction
• static control circuit
• static amplifier
• dynamic circuit
• dynamic capacity
Static, dynamic in use

27. 2023/1/25 27
• To come near or nearer, as in space or time:
• To come or go near or nearer to:
• To come close to, as in appearance, quality, or condition; approximate:
– The performance approaches perfection.
• To make a proposal or overtures to with a specific end in view:
•
• To begin to deal with or work on:
•
– approached the task with dread.
Approach in dictionary

28. 2023/1/25 28
• With DRAM technology，this simple approach is
impossible since addressing a row of data without
rewriting it will destruct all data in the row because of the
dynamic nature.
Approach in text

29. 2023/1/25 29
• at the approach of
• be approaching (to)
• be difficult of approach
• be easy of approach
• make an approach to
• approach to
Approach in use

30. 2023/1/25 30
• A model or an original used as an archetype.
• A person or thing considered worthy of imitation.
• A plan, diagram, or model to be followed in making things:
– a dress pattern.
• A representative sample; a specimen.
• An artistic or decorative design:
Pattern in dictionary

31. 2023/1/25 31
• This aluminum pattern is defined by a lithographic mask
used in one of the last steps of manufacture. Therefore
these devices are often called mask-ROMs.
Pattern in text

32. 2023/1/25 32
• bit pattern
• beat pattern
• charge pattern
• circuit pattern
Pattern in use

33. 2023/1/25 33
• A term sometimes applied to a “composite” device; to a
device incorporating multiple elements of different type.
• A common short form used for “hybrid circuit” and
“hybrid network” mainly in the plural.
Hybrid in dictionary

34. 2023/1/25 34
• Fast cache memory can be constructed in BiCMOS
technology, a hybrid technology that uses bipolar
transistors for extra drive.
Hybrid in text

35. 2023/1/25 35
• Combined adj.
– combined circuit
– combined color image
• Composite adj.
– composite modulation
– composite coding
Hybrid in use

36. 2023/1/25 36
• To show the way to or the direction of; point out:
• To serve as a sign, symptom, or token of; signify:
• To suggest or demonstrate the necessity, expedience, or advisability of:
– The symptoms indicate immediate surgery.
• To state or express briefly:
– indicating her approval with a nod.
Indicate in dictionary

37. 2023/1/25 37
• The word ´dynamic´ indicates that the data is not held in a
flip-flop but rather in a storage cell.
Indicate in text

38. 2023/1/25 38
Indicate in use
• indicator
• voltage indicator
• status indicator

39. Thank You
2023/1/25 39