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TI486 Microprocessor - Al Kossow's Bitsavers

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Functional Timing<br />

Figure 3-17. Pipelined Cache Fills Using KEN (With Different Numbers of Wait States)<br />

CLK2<br />

Cycle 1 I Cycle 2<br />

Pipelined I Pipelined<br />

(Read - Cache Fill) (Read - Cache Fill) I<br />

T1P I T2P I T2P : T1P I T2P I T1P<br />

cp11 cp21 cp11 cp21 cp11 cp2 cp11 cp21 cp11 cp2 cp11 cp21<br />

A2SO~~, ~7Ia, ~M _,......v._a_lid_1_~........__...,.....__<br />

Va_li_d _2..,..-___"!!f-~__-t""-v._a_lid_3_.....,...--<br />

015-00<br />

(Input During Read)<br />

I<br />

--.L/<br />

I<br />

I<br />

x<br />

Valid 1<br />

\<br />

I<br />

i<br />

I I I I I I I<br />

I<br />

I<br />

-I I<br />

: ;,..--.i-: __ \<br />

I<br />

~ ~alid2<br />

I<br />

I<br />

I<br />

I<br />

I<br />

~<br />

I<br />

: ;,.-.;-: -<br />

I<br />

I<br />

I<br />

~ vali~3<br />

~--r----r--~--r--~--r--<br />

I I I I<br />

I I<br />

, I<br />

3.2.6.2 Flushing the Cache<br />

To maintain cache coherency with external memory, the <strong>TI486</strong>SLC/E cache<br />

contents should be invalidated when previously cached data is modified in<br />

external memory by another bus master. The <strong>TI486</strong>SLC/E invalidates the<br />

internal cache contents during execution of the INVD and WBINVD<br />

instructions, following assertion of HLDA if the BARB bit is set in the CGRD<br />

configuration register, or following assertion of FLUSH if the FLUSH bit is set<br />

in CCRD.<br />

3-35

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