AMD 8 manual Appendix B, Conventions and Abbreviations, Signals and Bits, Preliminary Information

Preliminary Information

25175H —March 2003 AMD Athlon™ XP Processor Model 8 Data Sheet

Appendix B

Conventions and

Abbreviations

This section contains information about the conventions and abbreviations used in this document.

Signals and Bits

■Active-Low Signals—Signal names containing a pound sign, such as SFILL#, indicate active-Low signals. They are asserted in their Low-voltage state and negated in their High-voltage state. When used in this context, High and Low are written with an initial upper case letter.

■Signal Ranges—In a range of signals, the highest and lowest signal numbers are contained in brackets and separated by a colon (for example, D[63:0]).

■Reserved Bits and Signals—Signals or bus bits marked reserved must be driven inactive or left unconnected, as indicated in the signal descriptions. These bits and signals are reserved by AMD for future implementations. When software reads registers with reserved bits, the reserved bits must be masked. When software writes such registers, it must first read the register and change only the non-reserved bits before writing back to the register.

■Three-State—In timing diagrams, signal ranges that are high impedance are shown as a straight horizontal line half-way between the high and low levels.

Appendix B - Conventions and Abbreviations 87