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Regardless of the memory or I/O maps, if the BTHRDY pseudo-variable equals TRUE the
target system must return a valid READY signal for each bus cycle (except HALT and SHUT
DOWN) that the processor initiates. Otherwise, a time-out will occur if one or more of the
time-out pseudo-variables are enabled (time-outs are enabled by default). The time-out
pseudo-variables are the following:
•
BUS ACT allows a system time-out when the processor bus is inactive for more than one
second.
•
IORDY allows a system time-out when an I/O access takes more than one second.
•
MEMRDY allows a system time-out when memory access time is longer than one second.
•
PHANG allows a system time-out when coprocessor memory accesses exceed one second
(8086/8088 and 80186/80188 probes only).
Erratic operation can occur if READY violates the setup or hold requirements or is asserted at
the wrong time during a bus cycle. If the time-out pseudo-variables are disabled and the target
system does not provide READY, the PICE HALT command will not return the probe to
interrogation mode; return to interrogation mode by entering the RESET UNIT command.
Mapping Input/Output
The MAPIO command displays or changes the PICE I/O map. If you display the I/O map right
after invoking PICE software, you will see all I/O ports mapped to USER, as shown in the
following example:
m m o
MAPIO 0 LENGTH 1 D 0 00 H USER
The I/O map determines the source of input data and the destination of output data. You can
map I/O ports to USER or ICE. The prototype hardware reads or writes I/O ports mapped to
USER.
All bus cycles (memory reads and writes, interrupt acknowledges, I/O reads and writes, and
halt cycles) initiated by the processor in the PICE system are active in the target system
Introduction to Using the PICE™ System
After the command is executed, program memory values are the
following:
Address
Value at that address
.start
. start +1
.start+ 2
.start+ 3
.start+ 4
.start+ 5
.start+ 6
The algorithmn used by the PICE system reads from program mem
ory, even though you designated the partition as WRITE with the
MAP command.
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