HP 64783A, Руководство пользователя

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Understanding Emulation and Analysis Of The
Memory Management Unit
You only need to read this chapter if you are using the on-chip MMU (Memory
Management Unit) of the MC68040 or MC68LC040 microprocessor. If you are
using an MC68EC040, or if you are using an MC68040 or MC68LC040 with its
MMU disabled, you won’t need the information in this chapter.
This chapter begins with a discussion of terms and conditions you need to
understand when you are using the MC68040 or MC68LC040 emulator/analyzer
with the MMU enabled. Under these conditions, many capabilities and features
become available that are not otherwise offered. Also, some of the features you
have been using behave differently. These are discussed in this chapter.
Terms And Conditions You Need To Understand
The following paragraphs explain the differences between logical and physical
memory, and between static and dynamic virtual memory systems.
Logical vs Physical
When you develop a program, compile it or assemble it, and link it, addresses are
assigned to contain each of the bytes of the program. These addresses are logical
addresses. When the program is loaded into hardware memory so that it can be
executed by the microprocessor, it is loaded into physical address space. When you
are not using an MMU, the program is loaded into physical memory hardware at
the logical addresses assigned in the linker load map. Under these conditions, there
is no need to differentiate between logical addresses and physical addresses because
they are the same (simply addresses). When you use the MMU, it becomes
necessary to understand the difference between logical addresses and physical
addresses.
Most emulation and analysis commands that require an address as part of the
command use logical addresses. Some emulation and analysis commands will
accept either logical or physical addresses.
Chapter 10: Using Memory Management
Understanding Emulation and Analysis Of The Memory Management Unit
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