Intel i86W Manual page 8

PREFACE
• Chapter 9, "Programming Examples," illustrates the use of the i860 microprocessor
by presenting short code sequences in assembly language.
• The appendices present instruction formats and encodings, timing information, and
summaries of instruction characteristics. These appendices are of most interest to
assembly-language programmers and to writers of assemblers, compilers, and
debuggers.
RELATED DOCUMENTATION
The following books contain additional material concerning the i860 microprocessor:
• i860™ 64-Bit Microprocessor
(Data Sheet), order number 240296
• i860™ 64-Bit Microprocessor Assembler and Linker Reference Manual, order number
240436
• i860™ 64-Bit Microprocessor Simulator-Debugger Reference Manual,
order number
240437
NOTATION AND CONVENTIONS
The instruction chapters contain an algorithmic description of each instruction that uses
a notation similar to that of the Algol or Pascal languages. The metalanguage uses the
following special symbols:
• A
~
B indicates that the value of B is assigned to A.
• Compound statements are enclosed between the keywords of the "if' statement (IF
... , THEN ... , ELSE ... , FI) or of the "do" statement (DO ... , OD).
• The operator
+ +
indicates auto increment addressing.
• Register names and instruction mnemonics are printed in a contrasting typestyle to
make them stand out from the text; for example,
dirbase.
Individual programming
languages may require the use of lowercase letters.
Hexadecimal constants are written, according to the C language convention, with the
prefix Ox. For example, OxOF is a hexadecimal number that is equivalent to decimal 15.
RESERVED BITS AND SOFTWARE COMPATIBILITY
In many register and memory layout descriptions, certain bits are marked as reserved or
undefined.
When bits are thus marked, it is essential for compatibility with future pro-
cessors that software not utilize these bits. Software should follow these guidelines in
dealing with reserved or undefined bits:
• Do not depend on the states of any reserved or undefined bits when testing the values
of registers that contain such bits. Mask out the reserved and undefined bits before
testing.
• Do not depend on the states of any reserved or undefined bits when storing them in
memory or in another register.
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