Index Register Select

Index Register Select is a flag in the processor status register (bit 5). It indicates how wide the index registers are.

When clear, both index registers are 16 bits wide. When set, both index registers are 8 bits wide.

It is not possible to control the width of the two index registers individually.

It can be affected by:

• REP
• SEP
• PLP
• RTI

See Also

• Memory/Accumulator Select