Programming Model

DRAM Attributes Register

To satisfy DRAM component requirements before the memory is used at

!start-up, software must always wait at least 500μs after the initial setting

Caution

 

of a bank’s size bits to a nonzero value before the initial access to that

 

 

 

 

bank. These settings are stored in the DRAM Attributes register (offset

 

 

 

 

$FEF80010). The delay is introduced to ensure that the bank has been

 

 

 

 

refreshed at least eight times before use. The 500μs interval is sufficient,

 

 

 

as the CLK Frequency register (offset $FEF80020) is within a factor of

 

 

 

 

two of matching the actual processor clock frequency.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ADDRESS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

$FEF80010

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NAME

ram

0

 

0

0

0

ram

ram

ram

ram

0

0

0

0

ram

ram

ram

 

 

ram

0

0

0

0

ram

ram

ram

 

 

ram

0

0

0

0

ram

ram

ram

 

 

 

 

 

 

 

 

 

 

 

 

a en

 

 

 

 

 

a siz0

a siz1

a siz2

b en

 

 

 

 

b siz0

b siz1

b siz2

 

 

c en

 

 

 

 

c siz0

c siz1

c siz2

 

 

d en

 

 

 

 

d siz0

d siz1

d siz2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OPERATI

R/W

R

 

R

R

R

R/W

R/W

R/W

R/W

R

R

R

R

R/W

R/W

R/W

R/W

R

R

R

R

R/W

R/W

R/W

R/W

R

R

R

R

R/W

R/W

R/W

ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESET

0

X

X

X

X

0

0

0

0

X

X

X

X

0

0

0

0

X

X

X

X

0

0

0

0

X

X

X

X

0

0

0

 

PL

 

 

 

 

 

P

P

P

PL

 

 

 

 

P

P

P

PL

 

 

 

 

P

P

P

PL

 

 

 

 

P

P

P

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ram a/b/c/d en

Control bits that enable accesses to the corresponding block of DRAM when set, and disable them when cleared.

ram a/b/c/d siz0-2

These control bits define the size of their corresponding block of DRAM. Table 3-12shows the block configuration assumed by the Falcon pair for each value of ram siz0-ram siz2.

3

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

3-33

Page 195
Image 195
Motorola MVME2300 Series manual Dram Attributes Register, Ram a/b/c/d en, Ram a/b/c/d siz0-2