AMD AMD5K86 - Software Environment and Extensions

18524BjO-Mar1996
AMD~
AMD5iJ6 Processor Technical Reference Manual
3
Software Environment and
Extensions
The AMD5
K
86 processor is compatible with the instruction set,
programming model, memory management mechanisms, and
other software infrastructure supported by the 486 and Pen-
tium (735\90,815\100) processors. Operating system and appli-
cation software that runs on the Pentium processor can be
executed on the AMD5
K
86 processor without modification.
Because the AMD5
K
86 processor takes a significantly different
approach to implementing the x86 architecture, some subtle
differences from the Pentium processor may be visible to sys-
tem and code developers. These differences are described in
AppendixA.
The AMD5
K
86 processor implements the following extensions
to the 486 architecture:
• 4-Mbyte Page Size
•
Global Pages
• Protected Virtual Extensions
• Virtual-8086 Mode Extensions (VME)
• Machine-Check Registers and Exceptions
• Model-Specific Registers (MSRs)
•
Time Stamp Counter (TSC)
•
New Instructions: CPUID, CMPXCHG8B, MOV to and from
CR4, RDTSC, RDMSR, WRMSR, and RSM
• 110 Breakpoints
3-'