Overall Context:

️· This is an excerpt from the IA70C20 microcontroller's documentation, specifically focusing on addressing modes used in its assembly language.

1. Addressing Modes - Overview

️· The IA70C20 assembly language supports *eight* addressing modes.

2. Single-Register Addressing Mode

️· Purpose: Uses a single register (Rn, where n ranges from 0 to 127) as an operand. A and B represent registers 0 and 1 respectively.
️· Object Code Format: The object code layout depends on if register A or B is used as the operand. (See Figure 1 in the text - it describes the format).
- `OPCODE OPCODE Rn` (if Rn is the operand)

3. Dual-Register Addressing Mode

️· Purpose: Uses *two* registers: a source and a destination. The source is always listed first in the assembly language.
️· Object Code Format: The byte requirements vary based on the instruction type. (See Figure 2). The first byte is always the opcode.

4. Peripheral-File Addressing Mode

️· Purpose: Handles I/O operations. Uses ports (Pn) to read from or write to peripherals.
️· Instructions: `MOVP`, `ANDP`, `ORP`, `XORP`.
️· Object Code Format: The format depends on if the destination is the peripheral or a general-purpose register. (See Figure 3).

5. Immediate Addressing Mode

️· Purpose: Uses a *constant* eight-bit value directly within the instruction. This value can be represented as a constant or labeled with a percent sign (%).
️· Format: `%value`
️· Notes: The `MOVD` instruction uses 16-bit immediate operands.

Key Figures & Tables:

️· Table 1: Lists the eight addressing modes and provides simple examples.
️· Figure 1: Shows the object code layout for single-register addressing.
️· Figure 2: Illustrates the byte requirements for dual-register instructions.
️· Figure 3: Shows the byte requirements for peripheral-file instructions.



In essence, this documentation segment explains how different types of data (registers, peripherals, constants) are referenced and used within IA70C20 assembly language programs.