REFRESH CONTROL UNIT

T1

T1

T1

T1

T1

T4

T1

CLKOUT

 

 

 

 

 

 

 

1

3

 

4

 

 

HOLD

 

 

 

 

 

 

 

 

2

 

 

 

 

HLDA

 

 

 

 

 

 

 

 

 

 

 

 

6

AD15:0

 

 

 

 

 

 

DEN

 

 

 

 

 

 

RD, WR,

 

 

 

 

5

 

BHE, S2:0

 

 

 

 

 

 

 

 

 

 

 

DT / R,

 

 

 

 

 

 

A19:16

 

 

 

 

 

 

NOTES:

1.HLDA is deasserted; signaling need to run DRAM refresh cycles less than TCLHAV.

2.External bus master terminates use of the bus.

3.HOLD deasserted; greater than THVCL.

4.Hold may be reasserted after one clock.

5.Lines come out of float in order to run DRAM refresh cycle.

A1534-0A

Figure 7-9. Regaining Bus Control to Run a DRAM Refresh Bus Cycle

7-13

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Image 192
Intel 80C188XL, 80C186XL user manual Clkout Hold Hlda DEN, RD, WR BHE, S2 DT / R A1916