
Instruction Set Overview
B-5
Instruction Set Description
B.1.1.2 Single Operand Instructions (Core Instructions)
The instruction format using a single operand, as shown in Figure B–2,
consists of two main fields to form a 16-bit code:
operational code field, nine bits with four MSBs equal to 1h
byte operation identifier, one bit [B/W]
destination field, six bits [destination register + Ad]
The destination field is composed of two addressing bits and the four-bit
register number (0....15). The destination field bit position is the same as that
of the two operand instructions. The byte identifier (B/W) indicates whether the
instruction is executed as a byte (B/W = 1) or as a word (B/W = 0).
Figure B–2.Single-Operand Instructions
B/W Destination Register
15 0
0
9712 11 6 5 4 3
00 1X XXXX
Ad
10
Destination FieldOperational Code Field
Status Bits
VNZC
RRA[.W]; RRA.B dst MSB → MSB ...LSB → C0***
RRC[.W]; RRC.B dst C → MSB ........LSB → C****
PUSH[.W]; PUSH.B dst SP – 2 → SP, src → @SP – – – –
SWPB dst swap bytes – – – –
CALL dst PC→2 + @SP, dst → PC – – – –
RETI dst TOS → SR, SP + 2 → SP * * * *
TOS → PC, SP + 2 → SP
SXT dst Bit 7 → Bit 8 ........ Bit 15 0 * * *
B.1.2 Conditional and Unconditional Jumps (Core Instructions)
The instruction format for conditional and unconditional jumps, as shown in
Figure B–3, consists of two main fields to form a 16-bit code:
operational code (op-code) field, six bits
jump offset field, ten bits
The operational-code field is composed of the op-code ( three bits), and three
bits according to the following conditions.
Figure B–3.Conditional and Unconditional Jump Instructions
15 091213
001 X X X X X
10
Operational Code Field
XX XX XXXX
OP-Code Jump-On Code
Sign Offset
Jump Offset Field
Conditional jumps jump to addresses in the range of –511 to +512 words
relative to the current address. The assembler computes the signed offsets
and inserts them into the op-code.
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