This document provides an overview of different types of computer memory, including RAM, ROM, and hybrid memory. It describes the characteristics of SRAM and DRAM, the most common types of RAM memory. DRAM is cheaper and slower than SRAM, and must be periodically refreshed. The document outlines the evolution of DDR RAM standards and their internal structures. ROM includes mask ROM, PROM, EPROM, and is read-only memory that can be programmed during manufacture or special modes. Hybrid memory such as flash memory has qualities of both RAM and ROM.

1. RAM and ROM Memory
Overview

2. Introduction

Types of Memory

RAM Memory

ROM Memory

Hybrid Memory

3. Types of Memory

4. RAM Memory

SRAM-Static Random-Access Memory

DRAM - Dynamic Random-Access Memory

5. SRAM

SRAM Internal Structure

6. SRAM Memory

Fastest type of memory

Low density

More expensive

Generally used in small amounts (L2 cache) or
expensive servers

7. DRAM Memory

DRAM Internal Structure

8. Types of DRAM

SDRAM - Synchronous dynamic RAM

DDR RAM - Double data rate RAM

DDR2 RAM

DDR3 RAM

DDR4 RAM

9. DRAM Memory

Very high density

Cheap data cache in computers

Must be periodically refreshed

Slower than SRAM

Volatile

10. DDR Internal Structure
12
10
8
Column 1
Column 2
Column 3
6
4
2
0
Row 1
Row 2
Row 3
Row 4

11. DDR2 Internal Structure

12. DDR3 Internal Structure

13. DDR Comparison

14. DDR3 and DDR4 Review

15. DDR4 Memory

16. SRAM Memory Interface

17. SDRAM Memory Interface

18. DDR Memory Inreface

21. SRAM vs DRAM

SRAM is faster compared to DRAM

SRAM consumes less power than DRAM

SRAM uses more transistors per bit of memory
compared to DRAM

22. SRAM vs DRAM Cont.


SRAM is more expensive than DRAM
Cheaper DRAM is used in main memory while
SRAM is commonly used in cache memory

DRAM Required Refresh cycle

DRAM Required EDC Circuit

23. ROM Memory

Mask ROM - Mask Read Only Memory

PROM - Programmable Read Only Memory

EPROM - Erasable Programmable Read Only
Memory

24. PROM Memory

25. ROM Memory

Programmable by special program tools/modes

Read only memory during normal use

Non-volatile

EPROM uses UV light to reset all bits

26. Hybrid Memory

Flash Memory

NVRAM - Non-volatile random-access memory

EEPROM - Electrically Erasable Programmable
Read-Only Memory

27. Flash Memory

NAND Flash Memory

NOR Flash Memory

28. Flash Memory Architecture

29. NAND Flash Memory

31. NAND Flash

33. NAND vs NOR Flash

34. NAND and NOR Pins

36. Selection Check Point



Most writes must be preceded by an erase
operation
NAND has smaller erase units for fewer erases
in less time
NOR is an XIP device

37. NAND Flash Memory

38. NAND Flash

39. NAND Flash

40. NAND Memory Interface

42. Memory Mapping in NOR Flash

43. NOR Flash Interface

44. Memory Mapping in NOR Flash

45. Any
Questions

46. Thank You