MC68HC05E0 Datasheet, PDF (6/96 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit

Conventions
Where abbreviations are used in the text, an explanation can be found in the
glossary, at the back of this manual. Register and bit mnemonics are defined in the
paragraphs describing them.
An overbar is used to designate an active-low signal, eg: RESET.
Unless otherwise stated, shaded cells in a register diagram indicate that the bit is
either unused or reserved; ‘u’ is used to indicate an undefined state (on reset).