HP 64782 User Manual page 137

Using the Emulator
In the previous figure, there is a block labeled DE-SIM module. It receives as
inputs from the 6833x:
•
Port C which can be BR, BG, BGACK, FC0-2, and A19-23 or CS0-10.
•
CSBOOT.
•
SIZ0,1.
The DE-SIM module provides as outputs:
•
Address lines A23-A19 and FC2-0 to the memory mapper and the analyzer.
•
A "bus cycle in progress" signal based upon AS or chip selects.
The 6833x SIM is configured through the registers in the SIM register class;
these registers control how the 6833x uses external signal lines to access
memory.
The emulator's DE-SIM module is configured through the registers in the
EMSIM register class. The DE-SIM module controls how the emulator
interprets the signals from the 6833x when accessing emulation memory and
passing information to the analysis trace.
Normally, the SIM and EMSIM registers should be programmed with the same
values so they will be working together.
One of the primary functions of the DE-SIM is to provide A23-A19 to the
memory mapper and analyzer so they will have the complete 24-bit address
bus. This is easy if Port C of the 6833x is programmed as address lines;
however, if any of these lines are programmed as chip selects, the
corresponding address lines are not available external to the 6833x. The chip
selects, however, have access to the full 24-bit address inside the 6833x. You
can therefore locate memory using a chip select at an address that is not
possible to decode externally. If properly programmed, the DE-SIM can use
information in the programming of the chip selects to re-create the upper
address lines. This provides the ability to map emulation memory at these
addresses and also provides a correct address in the analysis trace so that
symbolic debugging is possible.
Normally, the DE-SIM would be programmed through the EMSIM registers to
match the programming of the 6833x SIM as it will exist after all of the
boot-up configuration is complete. This can be done before the boot-up code
is run. In fact, the programming of the EMSIM registers is part of the
configuration and will be loaded along with the memory map and other
configuration items when a configuration file is loaded.
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