ADDRESS SPACES

KS57C2308/P2308/C2316/P2316

 

 

EMB FLAG (EMB)

The EMB flag is used to allocate specific address locations in the RAM by modifying the upper 4 bits of 12-bit data memory addresses. In this way, it controls the addressing mode for data memory banks 0, 1 or 15.

When the EMB flag is "0", the data memory address space is restricted to bank 15 and addresses 000H–07FH of memory bank 0, regardless of the SMB register contents. When the EMB flag is set to "1", the general-purpose areas of bank 0, 1 and 15 can be accessed by using the appropriate SMB value.

+PROGRAMMING TIP — Using the EMB Flag to Select Memory Banks

EMB flag settings for memory bank selection:

1. When EMB = "0":

 

 

 

 

SMB

1

; Non-essential instruction since EMB = "0"

LD

A,#9H

 

 

 

LD

90H,A

;

(F90H)

A, bank 15 is selected

LD

34H,A

;

(034H)

A, bank 0 is selected

SMB

0

; Non-essential instruction since EMB = "0"

LD

90H,A

;

(F90H)

A, bank 15 is selected

LD

34H,A

;

(034H)

A, bank 0 is selected

SMB

15

; Non-essential instruction, since EMB = "0"

LD

20H,A

;

(020H)

A, bank 0 is selected

LD

90H,A

;

(F90H)

A, bank 15 is selected

2. When EMB = "1":

 

 

 

 

SMB

1

; Select memory bank 1

LD

A,#9H

 

 

 

LD

90H,A

;

(190H)

A, bank 1 is selected

LD

34H,A

;

(134H)

A, bank 1 is selected

SMB

0

; Select memory bank 0

LD

90H,A

;

(090H)

A, bank 0 is selected

LD

34H,A

;

(034H)

A, bank 0 is selected

SMB

15

; Select memory bank 15

LD

20H,A

; Program error, but assembler does not detect it

LD

90H,A

;

(F90H)

A, bank 15 is selected

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Image 26
Samsung KS57C2308 manual EMB Flag EMB, + Programming TIP Using the EMB Flag to Select Memory Banks