Motorola user manual Sixteen-Bit Compatibility Mode Configuration, DSP56301 RAM Configurations

Models: DSP56301

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Sixteen-Bit Compatibility Mode Configuration

3.5Sixteen-Bit Compatibility Mode Configuration

The sixteen-bit compatibility (SC) mode allows the DSP56301 to use DSP56000 object code without change. The SC bit (Bit 13 in the SR) is used to switch from the default 24-bit mode to this special 16-bit mode. SC is cleared by reset. You must set this bit to select the SC mode. The address ranges described in the previous sections apply in the SC mode with regard to the reallocation of X and Y data memory to program memory in MS mode, but the maximum addressing ranges are limited to $FFFF, and all data and program code are 16 bits wide.

3.6Internal Memory Configuration Summary

The RAM configurations for the DSP56301 are listed in Table 3-1.

Table 3-1.DSP56301 RAM Configurations

Bit Settings

 

 

Memory Sizes (in K)

 

 

 

 

 

 

 

MS

 

CE

Program RAM

X data RAM

Y data RAM

Cache

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

0

4

2

2

0

0

 

1

3

2

2

1

 

 

 

 

 

 

 

1

 

0

2

3

3

0

 

 

 

 

 

 

 

1

 

1

1

3

3

1

 

 

 

 

 

 

 

The actual memory locations for Program RAM and the Instruction Cache in the Program memory space are determined by the MS and CE bits, and their addresses are given in Table

3-2.

Table 3-2.DSP56301 RAM Address Ranges by Configuration

MS

 

CE

 

Program RAM Location

Cache Location

 

 

 

 

 

 

 

 

 

 

 

 

0

 

0

 

$000–$FFF

N/A

0

 

1

 

$000–$BFF

$C00–$FFF1

1

 

0

 

$000–$7FF

N/A

 

 

 

 

 

 

1

 

1

 

$000–$3FF

$400–$7FF1

Note: 1.

When enabled, the internal memory location is not accessible and the address range is assigned to external

 

program memory.

 

 

 

 

 

 

 

 

3-6

DSP56301 User’s Manual

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Motorola DSP56301 user manual Sixteen-Bit Compatibility Mode Configuration, Internal Memory Configuration Summary