Table of Contents

Branch on Less Than (LSS)/OP=21

Format

OP A Syllable

OP = 21

The A Syllable is the branch address. Address may be indexed, indirect or extended. When not extended the final address controller bits specify the most significant digit of the address. This permits branching to any adddress up to and including 299,998 relative to Base #1 without indexing or extension. When the address is indexed, the final base indicant should resolve to a value of 1. The processor will always treat the resolved address as being relative to Base #1. The processor will not check for improper memory assignments.

Function

If the Comparison Flags are LOW, the A address is selected as the next program instruction address otherwise the next instruction is fetched with no significant action.

The address field of a non-taken branch must have the same attributes as any address, however the address does not have to resolve to a valid address. For example, a six-digit address may not contain an undigit in the extended digit position as this condition causes the processor to mistakenly treat this address as an eight digit address. An odd address only causes errors if the branch is taken.

Undigits in address positions other than the address controller and extended digit may result in incompatible behavior (see Compatibility Notes A.51).

Notes

Use of branch prediction op codes may result in incompatible behavior. See Compatibility Notes A.06.

Comparison Flags

The Comparison Flags are not modified by this instruction.