IA70C20 Datasheet, PDF (16/27 Pages) InnovASIC, Inc – 8-Bit Microcontroller

IA70C20
8-Bit Microcontroller
Figure 7. Register-File Indirect Addressing Mode Object Code
(PC)
(PC + 1)
OPCODE
RRnn
Rn-2
Rn-1
Rn
Rn+1
3.8 Indexed Addressing Mode
Data Sheet
August 19, 2008
16-Bit
Effective
Address
In indexed addressing mode, a 16-bit address formed by adding the contents of
the B register to a 16-bit direct memory address is used to access the operand.
The assembly language statement for the indexed addressing mode contains the
direct memory address written as a 16-bit constant value or a label, preceded by
an @ sign and followed by a B in parentheses: @LABEL(B). The addition
automatically transfers any carries into the MSB. Figure 8 illustrates how the
object code produced by an instruction using the indexed addressing mode
generates a 16-bit effective address.
Figure 8. Indexed Addressing Mode Object Code
(PC)
(PC + 1)
(PC + 2)
1.1.1.1 OP
CO
ADDRDE
MSB
ADDR
LSB
Reg B
Index
16-Bit
Effective
Address
4. Instruction Overview
Following is a listing of assembly language instructions for the IA70C20. Labels,
mnemonics, operands, and comments must be separated by at least one space in the
assembly code:
TMS7000 Family Instruction Overview
Mnemonic
ADC
B,A
Rs,A
Rs,B
Rs,Rd
%iop,A
%iop,B
Opcode
69
19
39
49
29
59
Bytes
1
2
2
3
2
2
Cycles
Tc(C)
5
8
8
10
7
7
Status
CNZI
RRRx
Operation Description
(s) + (Rd) + (C)  (Rd)
Add the source, destination, and
carry bit together. Store at the
destination.
IA211030117-05
Page 16 of 27
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