Functional Description

Table 3-4. PowerPC Bus to DRAM Access Timing — 50ns Hyper Devices

 

 

Clock Periods Required For:

 

Total

Access Type

 

 

 

 

 

 

1st

 

2nd

3rd

 

4th

 

 

Clocks

 

 

 

 

Beat

 

Beat

Beat

 

Beat

 

 

 

 

 

 

 

 

 

4-Beat Read after Idle (Quad-

8

 

1

1

 

1

11

word aligned)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4-Beat Read after Idle (Quad-

8

 

2

1

 

1

12

word misaligned)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4-Beat Read after 4-Beat Read

5/2 1

 

1

1

 

1

8/5

(Quad-word aligned)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4-Beat Read after 4-Beat Read

4/2 1

 

2

1

 

1

8/6

(misaligned)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4-Beat Write after Idle

4

 

1

1

 

1

7

 

 

 

 

 

 

 

 

4-Beat Write after 4-Beat Write

4/3 1

 

1

1

 

1

7/6

(Quad-word aligned)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1-Beat Read after Idle

8

 

-

-

 

-

8

 

 

 

 

 

 

 

1-Beat Read after 1-Beat Read

7/5 1

 

-

-

 

-

7/5

1-Beat Write after Idle

4

 

-

-

 

-

4

 

 

 

 

 

 

 

1-Beat Write after 1-Beat Write

9/7 1

 

-

-

 

-

9/7

Notes

1.These numbers assume that the PowerPC 60x bus master is doing address pipelining with TS_ occurring at the minimum time after AACK_ is asserted. Also, the two numbers shown in the 1st Beat column are for page miss/page hit.

2.In some cases, the numbers shown are averages and specific instances may be longer or shorter.

3

http://www.motorola.com/computer/literature

3-9

Page 171
Image 171
Motorola MVME2300 Series manual PowerPC Bus to Dram Access Timing 50ns Hyper Devices