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instruction and its operands are located in on-chip memory. The following symbols are used:
Symbol
Meaning
Imm.
Immediate data (3, 8, or 16 bits)
abs.
An absolute address (8 bits or 16 bits)
disp.
Displacement (8 bits or 16 bits)
rs, rd, rn
General register number (3 bits or 4 bits) The s, d, and n correspond to the
letters in the operand notation.
Register Designation: 16-bit general registers are indicated by a 3-bit rs, rd, or rn value. 8-bit
registers are indicated by a 4-bit rs, rd, or rn value. Address registers used in the @Rn,
@(disp:16, Rn), @Rn+, and @-Rn addressing modes are always 16-bit registers. Data registers
are 8-bit or 16-bit registers depending on the size of the operand. For 8-bit registers, the lower
three bits of rs rd, or rn give the register number. The most significant bit is 1 if the lower byte
of the register is used, or 0 if the upper byte is used. Registers are thus indicated as follows:
16-Bit register
Register
rs, rd, or rn
0 0 0
0 0 1
:
1 1 1
R0
R1
:
R7
8-Bit registers
rs, rd, or rn
Register
0 0 0 0
0 0 0 1
:
0 1 1 1
1 0 0 0
1 0 0 1
:
1 1 1 1
R0H
R1H
:
R7H
R0L
R1L
:
R7L
Bit Data Access: Bit data are accessed as the n-th bit of a byte operand in a general register or
memory. The bit number is given by 3-bit immediate data, or by a value in a general register.
When a bit number is specified in a general register, only the lower three bits of the register are
significant. Two examples are shown below.
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