Programming Model

Table 3-4. DRAM Size Control Bit Encoding

DZ2 - DZ0

Memory Size

 

 

$0

Not defined for MVME172

 

 

$1

Not defined for MVME172

 

 

$2

Not defined for MVME172

 

 

$3

Not defined for MVME172

 

 

$4

4 MByte (non-interleaved)

 

 

$5

8 MByte (non-interleaved)

 

 

$6

DRAM is not present.

 

 

$7

16 MByte (interleaved)

 

 

DRAM/SRAM Options Register

Note that this register is read only and is initialized at reset.

ADR/SIZ

 

 

 

$FFF42024 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

23

22

21

 

20

19

 

18

17

16

 

 

 

 

 

 

 

 

 

 

 

NAME

 

 

F0

 

SZ1

SZ0

 

DZ2

DZ1

DZ0

 

 

 

 

 

 

 

 

 

 

 

OPER

R

R

R

 

R

R

 

R

R

R

 

 

 

 

 

 

 

 

 

 

 

RESET

 

 

 

Application Specific

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DZ2-DZ0DZx bits indicate the size and architecture of the non-ECC DRAM array. Software must initialize the DRAM Space Size Register ($FFF42024 bits 26 - 24) based on the value of DZ2 - DZ0. DZ2 - DZ0 are initialized at reset to a value which is determined by the contents of a factory- programmed resident device.

SZ1-SZ0SZx bits indicate the size of the SRAM array. Software must initialize the SRAM Space Size Register ($FFF42024 bits 9 - 8) based on the value of SZ1 - SZ0.

3

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3-27

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Motorola MVME172 manual Dram Size Control Bit Encoding, DRAM/SRAM Options Register, DZ2 DZ0 Memory Size