1. Introduction to Computing
Lecture-06-Primary Memory
Muhammad Hafeez
Department of Computer Science
GC University Lahore

2. Today’s Agenda
RAM
Types of RAM

3. Primary Memory Stores three categories of items:
1. Operating System
2. Application Programs
3. Data used by application Programs
Role of primary memory to store both data and information is called stored program concept.

4. Primary Memory Data loaded in primary memory in bytes
Each byte is stored at a unique location in the primary memory
Hence, primary memory is called a byte-addressable memory
To access data and instructions memory the computer reference the address

5. Random Access Memory The processor read/ write data from RAM
The data is loaded in RAM from permanent storage such as Hard Disk Drives
Data stored in RAM is volatile.
Types of RAM
Two most common types of RAM are:
Dynamic RAM (DRAM)
Static RAM (SRAM)

6. Random Access Memory
DRAM: This type of RAM has to be reenergized constantly, otherwise it loses its content, many types of DRAM variations exists
SRAM: SRAM do not need to be reenergized more often, hence, they are more reliable. SRAM are faster than DRAM also much more expensive. Special application of SRAM are cache, registers

7. Variations of DRAM

8. Memory Bandwidth
A rate in which the data can be read/ write from/to RAM to processor
For example, a computer with dual-channel memory and one DDR2-800 module per channel running at 400 MHz would have a theoretical maximum memory bandwidth of=400,000,000 clocks per second × 2 lines per clock × 64 bits per line × 2 interfaces =102,400,000,000 (102.4 billion) bits per second (in bytes, 12,800 MB/s or 12.8 GB/s)

9. Memory Bandwidth
A rate in which the data can be read/ write from/to RAM to processor
For example, a computer with dual-channel memory and one DDR2-800 module per channel running at 400 MHz would have a theoretical maximum memory bandwidth of=400,000,000 clocks per second × 2 lines per clock × 64 bits per line × 2 interfaces =102,400,000,000 (102.4 billion) bits per second (in bytes, 12,800 MB/s or 12.8 GB/s)

10. Memory Slots SIMM: Single in-line Memory Module
Same types of connector on both sides
Old, legacy systems
DIMM: Dual in-line Memory Module
Different types of connectors on both sides
Most common type

11. Cache Memory
A fast SRAM in a limited capacity on motherboard that is used to frequently used instructions/ data it also minimize processor/ memory speed mismatch.
Types of Cache Memory
L1 Cache
L2 Cache
L3 Cache

12. Cache Memory L1 Cache L2 Cache L3 Cache
Directly built on processor, available in small capacity
L2 Cache
Slightly larger than L1 cache, ATC (Advance Transfer Cache) directly built on processor
L3 Cache
Available on motherboard, used on processor that use ATC cache
How processor search data/ information ?

13. Cache Memory

14. Machine Instruction Cycle

15. Machine Instruction Cycle

16. Machine Instruction Cycle
Fetch: Instruction fetch
Decode: Pass ALU the signal to process the instruction
Fetch Operands: send read signal to memory to read operands
Execute: Instruction is processed with the contents of DR/AC
Store: Result is stored in RAM with write signal

17. ROM (Read Only Memory)
A non-volatile memory to store permanent data that cannot be modified necessary for the operation of computer especially startup.
Most peripheral devices/ mobile devices also contains ROM chips i.e. printer has ROM chips to store Font data
Manufacturers of the electronic machines write permanent data/ instructions in ROM Chips that also called Firmware.
Types of ROM
EPROM, EEPROM

18. CPU Internal Architecture

19. Memory Hierarchy

20. Registers
A processor contains small, high-speed storage locations for temporary data/ information storage.
There are many types of registers, some perform specific task like controlling the functions others perform more general tasks.

21. Adapters Cards/ Expansion Slot/ Port
Adapter card is an electronic circuit board that enhances the functionality of a computer
Expansion slot is socket on motherboard that can hold an adapter card
PCI (Peripheral Component Interconnect)
PCI-Extended
PCI-Express
A port provides interface between peripheral devices and motherboard

22. Motherboard/ Adapter Cards/ Expansion Slots

23. Questions
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