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80C186EC/80C188EC Microprocessor User's Manual

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REFRESH CONTROL UNIT<br />

Register Name:<br />

Register Mnemonic:<br />

Register Function:<br />

Refresh Control Register<br />

RFCON<br />

Controls Refresh Unit operation.<br />

15 0<br />

R<br />

E<br />

N<br />

R<br />

C<br />

8<br />

R<br />

C<br />

7<br />

R<br />

C<br />

6<br />

R<br />

C<br />

5<br />

R<br />

C<br />

4<br />

R<br />

C<br />

3<br />

R<br />

C<br />

2<br />

R<br />

C<br />

1<br />

R<br />

C<br />

0<br />

A1311-0A<br />

Bit<br />

Mnemonic<br />

Bit Name<br />

Reset<br />

State<br />

Function<br />

REN<br />

Refresh<br />

Control Unit<br />

Enable<br />

0 Setting REN enables the Refresh Unit. Clearing<br />

REN disables the Refresh Unit.<br />

RC8:0<br />

Refresh<br />

Counter<br />

000H<br />

These bits contain the present value of the<br />

down-counter that triggers refresh requests.<br />

The user cannot program these bits.<br />

NOTE:<br />

Reserved register bits are shown with gray shading. Reserved bits must be written<br />

to a logic zero to ensure compatibility with future Intel products.<br />

Figure 7-8. Refresh Control Register<br />

7.7.2.4 Refresh Address Register<br />

The Refresh Address Register (Figure 7-9) contains address bits RA12:1, which will appear on<br />

the bus as A12:1 on the next refresh bus cycle. Bit 0 is fixed as a one in the register and in all<br />

refresh addresses.<br />

7-10

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