Intel 80C188XL, 80C186XL user manual Chapter Refresh Control Unit

Models: 80C186XL 80C188XL

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CHAPTER 7

CHAPTER 7

REFRESH CONTROL UNIT

The Refresh Control Unit (RCU) simplifies dynamic memory controller design with its integrat- ed address and clock counters. Figure 7-1 shows the relationship between the Bus Interface Unit and the Refresh Control Unit. Integrating the Refresh Control Unit into the processor allows an external DRAM controller to use chip-selects, wait state logic and status lines.

CPU

Clock

F-Bus

Refresh Clock

Interval Register

9-Bit Down

Counter

CLR

REQ

Refresh Control

Register

Refresh Base

Address Register

7

Refresh Request

 

BIU

 

 

 

 

Interface

Refresh Acknowledge

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9-Bit Address Counter

Refresh Address

Register

13

20-Bit

Refresh Address

A1539-01

Figure 7-1. Refresh Control Unit Block Diagram

7-1

Page 180
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Intel 80C188XL, 80C186XL user manual Chapter Refresh Control Unit