The operand notation used in this web presentation indicates the type of operands that can be used with the various instructions.
MAL instructions fall into five main categories.
The operand notation used in this web presentation indicates the type of operands that can be used with the various instructions.
The following symbols are used in the MAL machine instructions tables
to indicate the syntax required for a machine instruction operand.
These symbols are usually subscripted to distinguish between two source
operands or between source and destination operands.
The subscript d indicates a destination
operand and subscripts s, s1, and
s2 indicate source operands.
| Symbol | Meaning |
|---|---|
| label | an instruction label |
| addr | a memory address (see next table) |
| const | a constant |
| R | a general purpose register |
| Rc | a general purpose register or a constant |
| F | a floating point register |
| Fc | a floating point register or a constant |
| C | a control register |
Constants must be integers except for float (.s suffix) or
double (.d suffix) instructions.
| Symbol | Meaning |
|---|---|
| label | an instruction label |
| addr | a memory address (see next table) |
| const | a constant |
| R | a general purpose register |
| Rc | a general purpose register or a constant |
Constants must be integers.
The following modes can be used for memory addresses.
| Mode | Notation | Meaning |
|---|---|---|
| direct | label | The operand address is the address assigned to label |
| register direct | (R) | The operand address is the contents of register R |
| base displacement | const(R) | The operand address is the sum of the contents of register R and const |
In this table, R must be a general purpose register and const must be an integer constant.