Cortex-A15 Technical Reference Manual: Conventions

Conventions

Conventions that this book can use are described in:

Typographical

The typographical conventions are:

italic

Highlights important notes, introduces special terminology, denotes internal cross-references, and citations.

bold

Highlights interface elements, such as menu names. Denotes signal names. Also used for terms in descriptive lists, where appropriate.

monospace

Denotes text that you can enter at the keyboard, such as commands, file and program names, and source code.

monospace

Denotes a permitted abbreviation for a command or option. You can enter the underlined text instead of the full command or option name.

monospace italic

Denotes arguments to monospace text where the argument is to be replaced by a specific value.

monospace bold

Denotes language keywords when used outside example code.

< and >

Enclose replaceable terms for assembler syntax where they appear in code or code fragments. For example:

MRC p15, 0 <Rd>, <CRn>, <CRm>, <Opcode_2>

Timing diagrams

The figure named Figure 1 explains the components used in these diagrams. When variations occur they have clear labels. You must not assume any timing information that is not explicit in the diagrams.

Shaded bus and signal areas are undefined, so the bus or signal can assume any value within the shaded area at that time. The actual level is unimportant and does not affect normal operation.

Figure 1. Key to timing diagram conventions

Timing diagrams sometimes show single-bit signals as HIGH and LOW at the same time and they look similar to the bus change shown in Figure 1. If a timing diagram shows a single-bit signal in this way then its value does not affect the accompanying description.

Signals

The signal conventions are:

Signal level

The level of an asserted signal depends on whether the signal is active-HIGH or active-LOW. Asserted means:

HIGH for active-HIGH signals
LOW for active-LOW signals.

Lower-case n

At the start or end of a signal name denotes an active-LOW signal.

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