Z86L9900100ZEM Datasheet, PDF (42/70 Pages) Zilog, Inc. – ICEBOX

Counter Jumps to Unexpected Address
Troubleshooting Guide
11. Check P42 pin. If P42 stays low check the target pod and ensure that it is not shorting to
ground. If it is shorted, ensure that you are using the proper emulation pod, see Table 1-1.
12. After resetting the emulator, wait a minimum of 5 seconds before running ZDS.
13. If P42 always shows low, check the 40-pin target pod’s pin 31.
NOTE: The previous Z86L71 and Z86L98 ICEBOX 40 pin target pod have pin 31 connecting to
ground for emulating the L73/87/89. That target pod can not be used for Z86L990 emulation. Only use
the target cable which is shipped with the Z86L99 ICEBOX.
COUNTER JUMPS TO UNEXPECTED ADDRESS
Any instruction other than a DI instruction is used to disable interrupts. Possible causes
include:
• The stack overflows into the general register locations.
• Extra POP, PUSH, IRET, or RET is encountered (stack unbalanced).
• Program resets repeatedly.
– Program counter rolls over from value FFFF to 0000 and proceeds back to the
beginning of program.
– Watch-Dog Timer (WDT) is not initialized or refreshed.
• Unintialized interrupt vector is activated. The interrupt vector is not set to the interrupt
handler.
A–2
UM005100-IRR0400