Z89C00 View Datasheet(PDF) - Zilog

Part Name

Description

Manufacturer

Z89C00

16-BIT DIGITAL SIGNAL PROCESSOR

Zilog 

ZILOG

ADDRESSING MODES

PRELIMINARY

Z89C00

16-BIT DIGITAL SIGNAL PROCESSOR

This section discusses the syntax of the addressing modes used in the discussion of instruction syntax in the instruction

supported by the DSP assembler. The symbolic name is descriptions.

Symbolic Name

<pregs>

Syntax

Pn:b

Description

Pointer Register

<dregs>

Dn:b

(Points to RAM)

Data Register

<hwregs>

X,Y,PC,SR,P

EXTn,A,BUS

Hardware Registers

<accind>

@A

(Points to Program Memory)

Accumulator Memory Indirect

<direct>

<expression>

Direct Address Expression

<limm>

#<const exp>

Long (16-bit) Immediate Value

<simm>

#<const exp>

Short (8-bit) Immediate Value

<regind>

(Points to RAM)

<memind>

(Points to Program Memory)

@Pn:b

@Pn:b+

@Pn:b–LOOP

@Pn:b+LOOP

@@Pn:b

@Dn:b

@@Pn:b–LOOP

@@Pn:b+LOOP

@@Pn:b+

Pointer Register Indirect

Pointer Register Indirect with Increment

Pointer Register Indirect with Loop Decrement

Pointer register Indirect with Loop Increment

Pointer Register Memory Indirect

Data Register Memory Indirect

Pointer Register Memory Indirect with Loop Decrement

Pointer Register Memory Indirect with Loop Increment

Pointer Register Memory Indirect with Increment

There are eight distinct addressing modes for transfer of

data (Figure 4 and the table above).

<pregs>, <hwregs> These two modes are used for simple

loads to and from registers within the chip such as loading

to the Accumulator, or loading from a pointer register. The

names of the registers need only be specified in the

operand field. (Destination first then source)

<regind> This mode is used for indirect accesses to the

data RAM. The address of the RAM location is stored in the

pointer. The “@” symbol indicates “indirect” and precedes

the pointer, so @P1:1 tells the processor to read or write to

a location in RAM1, which is specified by the value in the

pointer.

<dregs> This mode is also used for accesses to the data

RAM but only the lower 16 addresses in either bank. The

4-bit address comes from the status register and the

operand field of the data pointer. Note that data registers

are typically used not for addressing RAM, but loading

data from program memory space.

14

DC 4083-00

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