1. HARDWARE ARCHITECTURE
MEMORY SYSTEM DESIGN

2. Learning Outcome Identify the types of memory chip and their functions
Define the difference between exhaustive and partial address decoder
Design address decoder using exhaustive and partial technique

3. Types of Memory ROM (Read-Only Memory)
containing permanent or semi-permanent data
ROM is non-volatile; even after turn off supply, the contents of ROM will remain
Used to store a program
Types available in market
PROM (Programmable ROM)
EPROM (Erasable PROM)
EEPROM (Electrically EPROM)

4. Types of Memory
ROM Block Diagram

5. Types of Memory RAM (Random Access Memory)
containing none permanent data
RAM is volatile, so data stored in RAM stays there only as long the supply is turn on
Used to store a temporary data
Types available in market
SRAM (Static RAM)
DRAM (Dynamic RAM)
EDORAM (Extended Data Output RAM)
BEDORAM (Burst EDORAM)
SDRAM (Synchronous DRAM)
DDR-DRAM (Double Data Rate-Synchronous DRAM)

6. Types of Memory
RAM Block Diagram

7. Address Decoder WHY? Functions
uP has too many device connected using bus system
Only one device can active or communicate with uP in one time
Functions
Monitor the state of address bus and determine when the memory chip
should be enabled

8. Designing Address Decoder
Before
Must know how much memory is needed
Calculate how many address line need to be used to locate memory
Begin
Draw memory map
Find the address range for every
component
Find based address
Find end address
Add Line = log (Memory Size) log 2
End Add = Based Add + Component (memory) Size -1

9. Designing Address Decoder
Draw address decoding table
Draw address decoder
Full address decoding technique
Partial address decoding technique
Device
Address Range
Address
Address line
A15 – A12
A11 – A8
A7 – A4
A3 – A0
First
Last

10. Designing Address Decoder
Exhaustive Decoding
All address lines must be used to access each physical memory location, either to access data or activate selected device
Partial Decoding
Not all the address lines available
for address decoding take part in
decoding process
Simplest and least expensive
Normally used decoder chips
74138
74139