Z89C6700ZEM Datasheet, PDF (3/6 Pages) Zilog, Inc. – Z8 GUI Emulator Software

Workaround: Always close the port window before
leaving the GUI.
7. Do not put breakpoint at address after Stop instruction.
This will cause program counter to continue at that
location after a Stop-Mode Recovery.
8. Breakpointing in interrupt service routine and single-
stepping pass the IRET statement will cause global
interrupts to be disabled.
9. Clicking on the HALT Button does not always Halt
ICEBOX execution.
10. Single-stepping into the HALT instruction will cause an
ICEBOX "Fatal Error".
11. Halting the program execution or breakpointing when
interrupts are enabled will globally disable interrupts.
If halting occurs, the program must be reset and
started from address %000c hex.
12. The C67 ICEBOX uses the Z86C50 ICE Chip; therefore,
emulation at more than 12 MHz requires that the
Expanded Register File (ERF) timing of the ICE Chip
be slowed down to SCLK x 2. This is accomplished by
loading value %01 to ICECON Register (Bank F,
Register A) of the ICE Chip.
Example:
PUSH RP
LD RP, #%0F
LD %A, #%01
POP RP
Z89C6700ZEM
CP95TAD0504
13. Due to the limitation in the Z86C50 ICE Chip, a software
workabound for the interrupt vector fetching must be
in place when configuring the emulator for ROMless
emulation.
ROM Emulation
The ROM emulation has the correct sequence for
vectored interrupts, shown as follows:
Push Program Counter (PC) lower byte on stack
Push PC upper byte on stack
Push FLAG on stack
Fetch the upper byte of vector
Fetch the lower byte of vector
Branch to service routine specified by vector
ROMless Emulation
ROMless emulation has the incorrect sequence for
vectored interrupts. This sequence is shown as follows:
Push PC lower byte on stack
Push PC upper byte on stack
Push FLAG on stack
Fetch the upper byte of vector
Write the upper byte of vector to high byte of PC
Fetch lower byte of vector according to the modified
PC
Branch to service routine specified by vector
The following figures illustrate the vectored interrupt
operation for ROM and ROMless emulation,
respectively:
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