Mapping Memory - HP 64751 User Manual

Mapping Memory

Because the emulator can use target system memory or emulation memory (or
both), it is necessary to map ranges of memory so that the emulator knows where to
direct its accesses.
Up to 7 ranges of memory can be mapped, and the resolution of mapped ranges is
256 bytes bytes (that is, the memory ranges must begin on 256 byte boundaries and
must be at least 256 bytes in length).
The emulator contains 4 Kbytes of dual-port emulation memory and provides two
slots for additional emulation memory modules:
•
HP 64171A 256 Kbyte Memory Modules or HP 64171B 1 Mbyte Memory
Modules (0 wait state emulation memory through 16.7 MHz, 1 wait state
above 16.7 MHz).
•
HP 64172A 256 Kbyte Memory Modules or HP 64172B 1 Mbyte Memory
Modules (0 wait state emulation memory through 25 MHz).
•
HP 64173A 4 Mbyte Memory Modules (0 wait state emulation memory
through 22 MHz, 1 wait state above 22 MHz).
(The 68340 processor is programmed for the correct number of wait states by user
code.) If memory modules are mixed, the performance characteristics of the slower
module should be used.
Emulation memory is made available to the mapper in blocks. When you map an
address range to emulation memory, at least one block is assigned to the range.
When a block of emulation memory is assigned to a range, it is no longer available,
even though part of the block may be unused.
Emulation memory in bank 0 of the emulator probe is divided into 4 equal blocks,
and memory in bank 1 is divided into 2 equal blocks. The 4 Kbyte block of
dual-port emulation memory is 1 block.
When you map ranges of emulation memory, blocks are allocated so as to leave the
greatest amount of emulation memory available. For example, if you map the range
0 through 0FFH as emulation memory, the 4 Kbyte block of dual-port memory is
used if possible; if that block has already been used, the next smallest available
block is used.
Chapter 5: Configuring the Emulator
Mapping Memory
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