COMPUTER SCIENCE Data Representation and Machine Concepts Section 1.2 Instructor: Lin Chen August 2013

1.2 Main Memory 1 Data Storage Memory Organization Measuring Memory Capacity

Memory Organization 1.2 Main Memory Computer Architecture Output Input

Memory Organization 1.2 Main Memory Memory consists of units Each unit is called a cell Cell

Memory Organization 1.2 Main Memory Memory consists of units Each unit is called a cell Cell 0 Cell 1 Cell 2 Cell 3 Cell 4 Cell 5 … …

Memory Organization 1.2 Main Memory Memory consists of units Each unit is called a cell Cell 0 Cell 1 Cell 2 Cell 3 Cell 4 Cell 5 … … Each cell contains 8 bits, called 1 byte 8 bits = 1 byte

Memory Organization 1.2 Main Memory Memory consists of units Each unit is called a cell Cell 0 Cell 1 Cell 2 Cell 3 Cell 4 Cell 5 … … Index High-order end Low-order end Most significant bitLeast significant bit

Memory Organization 1.2 Main Memory Save content into the memory … Address

Memory Organization 1.2 Main Memory Save content into the memory … Address

Memory Organization 1.2 Main Memory Save content into the memory … Address

Memory Organization 1.2 Main Memory RAM A random-access device, allows stored data to be accessed directly in any random order Read number from address 03 Return Write to address 02

Memory Organization 1.2 Main Memory DRAM (Dynamic Random Access Memory) Each bit of data is stored in a separate capacitor The capacitor charge need refresh periodically Responds as quickly as possible to changes in control inputs SDRAM (Synchronous DRAM) wait for a clock signal before responding to control inputs Only one word of data is transmitted per clock cycle DDR Two words are transmitted per clock cycle

1.1 Bits and Their Storage 32-bits system and 64-bits system Measuring Memory Capacity KB 10 bits MB 20 bits GB 2 30 = 1024 MB20 bits TB 2 40 = 1024 GB20 bits 32 bits physical address or 64 bits physical address 8 bit address (Hexadecimal) 2 8 bytes kilo byte mega byte giga byte tera byte

1.1 Bits and Their Storage Boolean Operations Questions: What is the memory in your notebook, SDRAM or DDR, DDR2, DDR3? What is the transmit speed of your memory? What is the capacity of your memory? What is your CPU frequency?