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80C186EC/80C188EC Microprocessor User's Manual

80C186EC/80C188EC Microprocessor User's Manual

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REFRESH CONTROL UNIT<br />

Register Name:<br />

Register Mnemonic:<br />

Register Function:<br />

Refresh Clock Interval Register<br />

RFTIME<br />

Sets refresh rate.<br />

15 0<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 />

A1288-0A<br />

Bit<br />

Mnemonic<br />

Bit Name<br />

Reset<br />

State<br />

Function<br />

RC8:0<br />

Refresh Counter<br />

Reload Value<br />

000H<br />

Sets the desired clock count between refresh<br />

cycles.<br />

NOTE:<br />

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

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

Figure 7-7. Refresh Clock Interval Register<br />

7.7.2.3 Refresh Control Register<br />

Figure 7-8 shows the Refresh Control Register. The user may read or write the REN bit at any<br />

time to turn the Refresh Control Unit on or off. The lower nine bits contain the current nine-bit<br />

down-counter value. The user cannot program these bits. Disabling the Refresh Control Unit<br />

clears both the counter and the corresponding counter bits in the control register.<br />

7-9

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