System Port

Table 4–14 21264/EV68A-to-System Commands Descriptions (Continued)

 

Command

 

Command

[4:0]

Function

 

 

 

ReadBlkMod

10001

Memory read with modify intent.

ReadBlkI

10010

Memory read for Istream.

FetchBlk

10011

Noncached memory read.

ReadBlkSpec2

10100

Speculative memory read (optional).

ReadBlkModSpec2

10101

Speculative memory read with modify intent (optional).

ReadBlkSpecI2

10110

Memory read for Istream (optional).

FetchBlkSpec2

10111

Speculative memory noncached ReadBlk (optional).

ReadBlkVic3

11000

Memory read with a victim (optional).

ReadBlkModVic3

11001

Memory read with modify intent, with a victim (optional).

ReadBlkVicI3

11010

Memory read for Istream with a victim (optional).

WrVictimBlk

00100

Write-back of dirty block.

CleanVictimBlk

00101

Address of a clean victim (optional).

Evict4

00110

Invalidate evicted block at the given Bcache index (optional).

ReadBytes

01000

I/O read, byte mask.

ReadLWs

01001

I/O read, longword mask.

ReadQWs

01010

I/O read, quadword mask.

WrBytes

01100

I/O write, byte mask.

WrLWs

01101

I/O write, longword mask.

WrQWs

01110

I/O write, quadword mask.

CleanToDirty6

11100

Sets a block dirty that was previously clean (optional for duplicate tags).

SharedToDirty6

11101

Sets a block dirty that was previously shared (optional for multiprocessor

 

 

systems).

STCChangeToDirty6

11110

Sets a block dirty that was previously clean or shared for a STx_C

 

 

instruction (optional for multiprocessor systems).

InvalToDirtyVic3,5

11011

Invalid to dirty with a victim (optional).

InvalToDirty5

11111

WH64 Acts like a ReadBlkMod without the fill cycles (optional).

4–22Cache and External Interfaces

21264/EV68A Hardware Reference Manual

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Compaq EV68A specifications 22Cache and External Interfaces