SI format

The operand fields of SI-format instructions designate immediate data and a virtual storage address.

┌────────┬─────────┬────┬────────────┐
│Op Code │    I₂   │ B₁ │     D₁     │
└────────┴─────────┴────┴────────────┘
0         8        16   20          31

Symbols used to represent immediate data (see HEX40 and TEN in the instructions labeled ALPHA2 and BETA1 in the examples) are assumed to be equated to absolute values 0 - 255.

Symbols used to represent implicit addresses (see IMPLICIT and KEY in the instructions labeled BETA1 and BETA2) can be either relocatable or absolute.

Symbols used to represent displacements (see DISPL40 in the instruction labeled ALPHA2 in the examples) in explicit addresses are assumed to be equated to absolute values 0 - 4095.

Examples:

ALPHA1   CLI             40(9),X'40'
ALPHA2   CLI             DISPL40(NINE),HEX40
BETA1    CLI             IMPLICIT,TEN
BETA2    CLI             KEY,C'E'

When assembled, the object code for the instruction labeled ALPHA1, in hexadecimal, is:

95409028

where

95: Is the operation code.
40: Is the immediate data.
9: Is the base register.
028: Is the displacement from the base register