Controlling Memory

What is a controller?

A device that controls all other devices

1 = device on

0 = device off

What number is used to switch a device on?

ID number

represents a device to be on all others will be off

Decoder

What is a decoder

A circuit that translates one format into another

Define binary decoder

Transforms n binary inputs into equivalent code with 2^n outputs

What does the binary decoder do?

Converts a binary ID number (ID code), into a binary number with a single bit 1 or 0

1 for each line to be turn on

0 for each line to be turned off

1-to-2 decoder

IF A = 0 TOP DEVICE IS ON

IF A = 0 BOTTOM DEVICE IS ON

2-to-4 decoder

3-to-8 decoder with enable

IF ENABLE = 1 DECODER IS ON

ELSE DECODER IS OFF

4-to-16 decoder

2-to-4 decoder and 4-to-1 multiplexer

Note: the read/output enable (RE/OE) write enable (WE)

Input output connected together and are connected to a bus anyway

1-bit memory cell using D flip-flop

This is an "atomic" circuit

2D grid addressable memory

Similar to SRAM

DRAM uses a multiplexer

Decoder