3

MC2 Chip

SRAM Space Base Address Register

ADR/SIZ

$FFF42020 (16 bits)

 

 

 

 

BIT

15-1

0

 

 

 

NAME

B31-B17

 

 

 

 

OPER

R/W

R

 

 

 

RESET

$FFE0 PL

 

 

 

 

B31-B17B31 - B17 are compared to local bus address signals A31

-A17 for memory reference cycles. If they compare, an SRAM cycle is initiated. Note that the same linkage that exists between the DRAM Base and Size Registers also exists for the SRAM decode logic. Refer to the DRAM Space Base Register description.

DRAM Space Size Register

ADR/SIZ

 

 

 

$FFF42024 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

31

30

29

 

28

27

 

26

25

24

 

 

 

 

 

 

 

 

 

 

 

NAME

 

 

 

 

 

 

 

DZ2

DZ1

DZ0

 

 

 

 

 

 

 

 

 

 

 

OPER

R/W

R/W

R/W

 

R/W

R/W

 

R/W

R/W

R/W

 

 

 

 

 

 

 

 

 

 

 

RESET

0 PL

0 PL

0 PL

 

0 PL

0 PL

 

0 PL

0 PL

0 PL

 

 

 

 

 

 

 

 

 

 

 

DZ2-DZ0The size bits configure the non-ECC DRAM decoder for a particular memory size. The following table defines their encoding. Note that the table specifies the allowed bit combinations for DZ2 - DZ0. Any other combinations generate unpredictable results.

DZ2 - DZ0 are set equal to the DZ2 - DZ0 bits of the

DRAM/SRAM Options Register. Note that changing DZ2

-DZ0 so that the DRAM architecture changes between interleaved and non-interleaved relocates the data. DZ2 - DZ0 are programmable to facilitate diagnostic software.

3-26

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Page 214
Image 214
Motorola MVME172 manual Sram Space Base Address Register, Dram Space Size Register