HP 64751 User Manual page 124

Chapter 5: Configuring the Emulator
Selecting the Emulation Monitor
Background Monitor
When a background monitor is selected, the Background Debug Mode (BDM) of
the 68340 processor is used. The BKPT line is asserted to enter the monitor.
Foreground Monitor
The foreground monitor is an assembly language program that is executed by the
68340 emulation microprocessor in its normal operating mode.
When a foreground monitor is selected, the foreground monitor or downloaded
custom monitor is loaded into dual-ported emulation memory and consumes a
4 Kbyte block of the 68340's address range.
The foreground monitor program is included with the interface software as
/usr/hp64000/monitor/fm64751.s. It can be assembled with the HP AxLS
68000/10/20 Assembler/Linker/Librarian or with the Microtec Research 68000
assembler and linker.
You may customize the foreground monitor if necessary; however, you must
maintain the basic communications protocol between the monitor and the emulation
system controller. Comments in the monitor program source file detail sections
that cannot be changed.
Comparison of Background and Foreground Monitor Programs
Monitor Program Characteristic
Takes up processor memory space
Allows the emulator to respond to target system
interrupts during monitor execution
Can be customized
Resident in emulator firmware
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Background
No
No
No
68340 emulation Yes, (custom monitor
processor's BDM must be assembled,
linked, and loaded)
Foreground
Yes, 4 Kbytes
Yes
Yes