Memory Organization

Microprocessor and Interfacing261313

CPU 8088 10 MHz 8/16 Bit1M RAM

CPU 80486 66 MHz 32 Bit8M RAM

Pentium 133 MHz 32 Bit16M RAM

Pentium MMX

200 MHz 32 Bit48M RAM

Pentium II 366 MHz 32 Bit128M RAM

Pentium M 1.6 GHz 32 Bit512M RAM

Core2 Duo 2.0 GHz 32/64 Bit4G RAM

0

500

1000

1500

2000

2500

CPU MHz

0

10

20

30

40

50

60

70

Bits

0

500

1000

1500

2000

2500

RAM (Mbytes)

MHz RAM

CPU Bits

What does “Bits” mean?

How many bits Is this PIC CPU?

ระบบ 32 Bit กำ��ลั�งเจอท�งตั�น?

RAM ใหญ่�ท��สุ�ดท��ระบบ 32 bit มองเห�นม�ค่��เป็�นเท��ใด?

Memory Limit of 32bit Machines

= 4 Giga Bytes

322

How to support bigger memory?

1.Upgrade to 64-bit systems

64-bit OS64-bit CPU

Limitation of moving to 64-bit systems

Need 64-bitHardware Drivers

Applicationsneed to be re-compiledwith a 64-bit compiler

How to support bigger memory?

2. Expand existing bits

วิ ธี�แกำ#ป็$ญ่ห�ของ Intel

Physical Address Extension (PAE)

4 bits 32 bits

362 = 64 GB

PAE Support

CPU with PAE(Since P-Pro)

PAE Aware OS

Benefits of PAE

Backward Compatible

Limitations

Taking advantage of the added memorystill requires changes in the software

Memory Limit of 64 Bit Machines?

?264

How big can we get?

1 kilobyte 1 megabyte 1 gigabyte 1 terabyte 1 petabyte 1 exabyte 1 zettabyte 1 yottabyte 1 xonabyte 1 wekabyte 1 vundabyte

1,024 1,048,576

1,073,741,824 1,099,511,627,776

1,125,899,906,842,624 1,152,921,504,606,846,976

1,180,591,620,717,411,303,424 1,208,925,819,614,629,174,706,176

1,237,940,039,285,380,274,899,124,224 1,267,650,600,228,229,401,496,703,205,376

1,298,074,214,633,706,907,132,624,082,305,024

สองเรื่��องน่ารื่� �เกี่��ยวกี่�บหน่วยความจำ�าของPIC Microcontroller

1. When Memory Grows Beyond Anticipation (เม��อหน่วยความจำ�าขยายโตเกี่�น่คาด)

1.1 กี่ารื่อ�างอ�งต�าแหน่งใน่ Flash Memory

K = 11 bitMaximum memory = 2^11 = 2K Bytes

PIC 16F877 has 8K Flash Memory: How do we access all of it?

PCLATH (F# 0x0A)

Bit 3-4 in PCLATH are usedfor memory access

07

Total Memory becomes 2^13 = 8K Bytes

Creating a 13 bit memory address

PCLATH

07

01012

CALL or GOTO k (Literal)

0101113

13 Bit Memory Address

OPCODE

PIC Flash Memory is Divided in to

4 Pages of 2KBytes

2K2K2K2K

01012

0x500 ค�าส��ง0x501 CALL 0x900

… …

0x900 ค�าส��งถั�ดไป

Fix this program

Address 0x900 exceeds 11 bits

0 1 0 101012

0x900 = 0 0 0 0 0 0 0 00

0x1000x01

0x4FF BCF PCLATH, 4

0x500 BSF PCLATH, 3

0x501 CALL 0x100

… …

0x900 ค�าส��งถั�ดไป

0 1 0 101012

0x900 = 0 0 0 0 0 0 0 00

0x1000x01