HP 68302 User Manual page 100

Chapter 4: Plugging the Emulator into Target Systems
Configuring the Emulator for In-Circuit Operation
foreground monitor since these functions will be "frozen" during all
background monitor operation. "Step 5. Decide whether to use the
foreground monitor" will further explain these issues.
While running in the background monitor, the watchdog timer will not be
serviced. However, knowing that the FRZ pin is asserted during background
monitor operation makes it easy for you to freeze the watchdog timer during
this time. Freezing the watchdog timer will be discussed later.
On-Chip Locations
Most of the special features of the 68302 are controlled via a 4 Kbyte block of
on-chip locations (RAM and special registers). The address of that 4 Kbyte
block is determined by the value written to the BAR. When you configure the
emulator, you must map that 4 Kbyte block of memory as target RAM.
Mapping that block as "guarded" or "emulation" memory will prevent proper
operation or result in guarded memory access errors.
Any display or modify of on-chip locations, including registers, requires the
emulation monitor program. If you do a display or modify of these locations
or registers while running your program, the emulator will briefly break into
the monitor, perform the display or modify, then return to your program.
Step 2. Set up your chip-selects
Failure to setup the chip-select registers is by far the most common cause of
problems when using the 68302 emulator. If you remember that load,
modify/display, step and run commands often rely on valid chip-select
settings, you can avoid most of the common mistakes made by users.
The 68302 has 4 chip-selects, only one of which is enabled after a reset
condition. Nearly all 68302 target systems rely on at least one chip-select for
accesses to memory. If you are going to access any target memory that relies
on a chip-select, then you MUST be sure that the appropriate chip-select
registers are initialized first. In some cases, even executing code from
emulation memory will require that you first initialize your chip selects. This
can be done in one of two ways:
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