Software Environment And Extensions - AMD K5 Technical Reference Manual

18524C/0—Nov1996
Software Environment and
Extensions
The AMD-K5 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 AMD-K5 processor without modification.
Because the AMD-K5 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
Appendix A.
The AMD-K5 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
I/O Breakpoints
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