Programming PDF – Topic 5: Memories

Topic 5: Memoirs

Index

Basic concepts

Characteristic parameters

Memory hierarchy

Main memory

Technologies

Structure

Memory map

Bibliography
Fundamentals of systems

digital
Thomas Floyd
Prentice-Hall

Computer Structure

José M. Angulo
Ed. Paraninfo

Foundations of the

Computers
Pedro de Miguel Anasagasti
Ed. Paraninfo

Department of Automatic

University of Alcalá

Fundamentals of Computer Technology

Basic concepts

Memory: part of the computer that
stores the information: instructions and
data. Set
of
memory with:

positions

of

Address:

identification

of

the

memory position

Content: stored information [19659002] addresses

selection
reading
writing

Memory cell: element that

stores a bit

Word: number of bits involved in
each operation with memory (8 , 16,
32, 64, … bits).
Data bus size

Basic operations:

Reading (R)
Writing or storage (W)

MEMORY

data

Basic memory scheme

Department of Automatic

University of Alcalá

2

Fundamentals of Computer Technology

T5 Memoirs

Characteristic parameters (I)

] Capacity: amount of information a device can store

Most common measures:

K ilobyte (Kb) =

210 bytes

Megabyte (Mb) = 210 Kb =

220 bytes

Gigabyte (Gb) = 210 Mb =

230 bytes

Terabyte (Tb) = 210 Gb =

240 bytes

Access speed or time: time elapsed since

provides the address to the memory and the data is available

Memory cycle: time between two accesses Consecutive

to memory. It may be higher than the access time

Cost per bit: price per bit of information

Department of Automatic

University of Alcalá

3

Fundamentals of Computer Technology

T5 Memoirs [19659002] Characteristic parameters (II)

Comparative

speed / capacity

Comparative

speed / cost

)
s
e
t
and
b
(

d
to
d
c
to
p
to
C

i

/

)
t
i
b
s
t
p
(

e
t
s
or
C

1s

10 ms

100 sm

1 sm
Access time

10 ns

1s

10 ms

100 sm

1 sm

10 ns

Access time

Department of Automatic

University of Alcalá [1965900] 2] 4

Fundamentals of Computer Technology

T5 Memories

Memory Hierarchy

Hierarchy:
CPU Registers
Internal Cache
External Cache
Main Memory
Storage devices

auxiliary / secondary

capacity
time of
access

CPU
Reg / Cache

price
per bit

level 1

CACHÉ

level 2

MAIN MEMORY

level 3

DISCS / CDs / DVDs

level 4

TAPE UNITS

Department of Automatic

University of Alcalá

5

Fundamentals of Computer Technology

T5 Memories

Main Memory: Technologies

RAM (Volatile, Read / Write)

Random Access Memory – Random Access Memory

SRAM – Static RAM [19659002] DRAM – Dynamic RAM

SDRAM – Synchronous Dynamic RAM – (RAM sin chrono and dynamics)

ROM (non-volatile, read-only)

Read Only Memory – Read-only memory

PROM – Programmable ROM – Programmable ROM

EPROM – Erasable PROM – PROM that can be erased ( ultraviolet light)

EEPROM – Electrically EPROM – PROM that can be erased (electrical signal)

Flash – Small erasure times (ms) and writing

Department of Automatic

Universidad de Alcalá

6

Fundamentals of Computer Technology

T5 Memories

Main Memory: Structure (I)

SELECTION

00002h

BUS ADDRESSES

20 bits

READING

WRITING

E
D
R
O
D
A
C
F
D
O
C
E
] D

I

I

I

S
E
N
O
C
C
E
R
D

I [19659002] s
to
d

i
l

to
S

0
2

2
⇒
s
a
d
a
r
t
n
E
0
2

1F20h
7C2Ah
047Fh
B123h [19659002] 5A93h
34E1h
1111h
AA55h

00000h

00001h

00002h

00003h

FFFFCh

FFFFDh

FFFFEh

FFFFFh

DATA BUS

16 bits

047Fh

Department of Automatic

University of Alcalá

7

Fundamentals of Computer Technology

T5 Memories

Main memory: structure (II )

Practical example: static RAM of 8kx8

R

S

M
A
6 2 6 4

D0
D1
D2

D7
D6
D5
D4
D3

BUS

ADDRESSES

A12-A0

CONTROL

WE

OE

CS1
CS2

SRAM
6264

8Kx8

D7-D0

BUS
DATA

Department of Automatic

] University of Alcalá

8

Fundamentals of Computer Technology

T5 Memories

Main memory: memory map (I)

Memory map
The memory map is
] addressable space of a
computer

m bits

Address

m-1

0

Memory

Available

0

2k-1

Map
used

The memory map comes
determined by the
size
of the addresses (and the bus
data). Thus, a size of
bits
addresses
allows
2m
addresses

"m"
address

of

"m" is the bus width of

addresses

Extension of the
memory map
It is not usually
to equip the computer with
all the memory that is
capable of addressing

2m-1

Location of RAM and ROM

00000h

Practical example:
memory map
simplified from
m P 8086

RAM

ROM

0FFFF0h
0FFFFFh

Map
total

Department of Automatic

University of Alcalá

9

Fundamentals of Computer Technology

T5 Memories

Main memory: memory map ( II)

Example of expansion of capacity (number of words):

Use of more than one chip to increase the range of addresses [194] 59004] A memory of 16 K-bytes is desired with 8Kx8 chips

A13

R / W

CS

13 bits

BUS DE

ADDRESSES

8Kx8

R / W

A12-A0

8 bits

BUS DE
DATA

CS

M1
8Kx8

R / W

CS

M2
8Kx8

R / W

8 bits

Department of Automatic

University of Alcalá

10

Fundamentals of Computer Technology

T5 Memories

Main memory: map memory (III)

Word size expansion example:

Use of more than one chip to increase the size of the data
A memory of 8 K-words (16 bits) with chips is desired of 8Kx8

R / W

CS

13 bits

BUS DE

ADDRESSES

R / W

CS

8Kx8

13 bits

BUS DE

ADDRESSES

8 bits

BUS DE
DATA [1965900] 2] R / W

CS

13 bits

8Kx8

8Kx8

8 bits

8 bits

16 bits

BUS DE
DATA

Department of Automatic

University of Alcalá

11

Fundamentals of Computer Technology

T5 Memories

.



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