Service manual

Service Manual
*PGo
Execute code on the target machine
Syntax
*PGo <exec addr>
*PGo -V <vector number>
Parameters
<exec addr> Address to begin execution
<vector number> Index into ROM vector table
The following vectors are currently defined:
0 Restart the test code at the beginning
1 Restart test code, ignoring test adapter
2 Restart test code, simulating power-on reset
3 Restart test code, expecting display adapter
4 Restart test code, simulating test link
5 Wait to receive command
6 Exit test code as though from soft reset
7 Exit test code as though from power-on reset
Note that RISC OS does not currently distinguish
between the effects of 6 and 7, and the test code will
behave similarly for vectors 1,2,3 and 4.
Use
Used to execute parts of the ROM test code or code
loaded onto the target machine with *PLoad. ROM-
resident code is normally executed through a vector
table providing protection against address changes in
later ROM versions.
Example
*PGo -v 7
Start RISC OS on the target machine.
Related commands
•PLoad
*PReset
Perform a hardware reset on the target machine
Syntax
*PReset
*PReset nn
*Preset -P
Parameters
Hold Reset permanently active
nn Cycle Reset with reset time nn microseconds
Use
Reset the target machine when some operation has
caused a crash or hang-up.
Generate cycling reset to make the first few execution
cycles visible. If about 25 microseconds of executions
is allowed, the first few bus cycles will be clearly
visible on an oscilloscope due to the high repetition
rate. This may be used to debug a system which
crashes before running the test code, by examining
the system signals for evidence of shorted address or
data lines, missing control signals etc.
Force a permanent Reset condition. This will cause
the ARM to generate a constantly-incrementing
address, which will therefore cycle round the entire
address space of the processor. The resulting
patterns may be used to check for address line
Integrity, address decode operation etc.
The *Reset command with no parameters may be
used to stop periodic resets or remove the permanent
reset condition. Note that *Reset -p and *Reset nn
return to the command prompt after setting the
operation up: it is not necessary to Esc from these
operations.
Example
*PReset 25
Generates a square wave on the processor reset
line with reset asserted for 25 microseconds and
execution enabled for 25 microseconds.
Related Commands
None
5-12 Issue 2, June 1991 Part 5 - Main PCB fault diagnosis