Instructions that use indexed addressing with an 8-bit offset have access to the first 511 locations in memory. These instructions execute in one less cycle and require one less byte of storage than their counterparts that use 16-bit offsets.
Target addresses are formed by taking the unsigned sum of the 8-bit offset and the contents of the index register and can range from $0000 (offset = $00 and X = $00) to $01FE (offset = $FF and X = $FF).
Most 68HC05 devices have 512 bytes of RAM or less, which makes indexed addressing with 8-bit offsets especially useful for operations on tabular or string data maintained in on-chip RAM.