Rainbow-electronics AT89C2051 Manuel d'utilisateur télécharger pdf (Page 8)

Microcontroller

5-54

Appendix A — Virtual Machine Architecture

Table 1.

Fundamental Resource Set

Table 2.

General Addressing Modes

Notes: 1. Addressing mode is in lower 3 bits of op code.

2. Mode S+ always pops 16 bits from stack. Only 16-bit values can be pushed.

3. Modes [S+] and [S] will always use a 16-bit address on the top pf the stack but the final target can be 8 or 16 bits.

ACC 16-bit accumulator 8-bit accesses are auto zero-filled

INDEX 16-bit addressing register, cannot be manipulated as 8 bits

SP 16-bit stack pointer

PC 16-bit program counter

Syntax Coding Description

#n x0 ii(ii) Immediate (8 or 16-bit operand)

aaaa x1 dd dd Direct memory address

I x2 Indirect (through INDEX register) no offset

n,I x3 oo Indirect (through INDEX register) with 8-bit offset

n,S x4 oo Indirect (through SP) with 8-bit offset

S+ x5 On Top of Stack (remove)

[S+] x6 Indirect through TOS (remove)

[S] x7 Indirect through TOS (leave on stack)

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Rainbow-electronics AT89C2051 Manuel d'utilisateur Page 8