Compaq 850 manual Notational Conventions, Signal Labels, Register Notation and Usage, BIT Notation

Chapter 1 Introduction

1.3NOTATIONAL CONVENTIONS

1.3.1 VALUES

Hexadecimal values are indicated by a numerical or alpha-numerical value followed by the letter “h.” Binary values are indicated by a value of ones and zeros followed by the letter “b.” Numerical values that have no succeeding letter can be assumed to be decimal.

1.3.2 RANGES

Ranges or limits for a parameter are shown using the following methods:

Example A: Bits <7..4> = bits 7, 6, 5, and 4.

Example B: IRQ3-7, 9 = IRQ signals 3 through 7, and IRQ signal 9

1.3.3 SIGNAL LABELS

Signal names are indicated using abbreviations, acronyms, or, if possible, the full signal name in all capital letters. Signals that are meant to be active (asserted) low are indicated with a dash immediately following the name.

1.3.4 REGISTER NOTATION AND USAGE

This guide uses standard Intel naming conventions in discussing the microprocessor’s (CPU) internal registers. Registers that are accessed through programmable I/O using an indexing scheme are indicated using the following format:

03C5.17h

Index port

Data port

In the example above, register 03C5.17h is accessed by writing the index port value 17h to the index address (03C4h), followed by a write to or a read from port 03C5h.

1.3.5 BIT NOTATION

Bit values are labeled with bit <0> representing the least-significant bit (LSb) and bit <7> representing the most-significant bit (MSb) of a byte. Bytes, words, double words, and quad words are typically shown with most-significant portions on the left or top and the least-significant portions on the right or bottom respectively.

1-2Compaq Deskpro EXS and Workstation 300 Personal Computers

Featuring the Intel Pentium 4 Processor

First Edition – December 2000