Service manual

Service Manual
You can select the standard POST sequence: in fact,
the display interface is hard-wired to generate this
command then passively display the resulting text
output. It is therefore also possible to display the POST
results on the host's display.
Note: if you attempt to access logical memory without
first setting up MEMC, the target will trap with an
exception error, jump to a vector which cannot be set
up, and crash. It is safe to access ROM (&3800000 to
&3FFFFFF) and physical memory space (&2000000 to
&2FFFFFF). You can address 10 space with careful
reference to the 10 address map.
The command syntax has been chosen to reflect the
similarity with the commands in the RISC OS *Debug
module. This results in rather untypeable commands:
the use of command aliases is recommended.
You can use the RISC OS Help command to provide
reminders of the Probe *Commands and their syntax.
For a detailed description of how the diagnostic
interface works, see the section entitled Display/debug
interface on page 5-14.
*PMemory
Display values in target system memory
Syntax
*PMemory [-BRQ] <addr1>
*PMemory [-BRQ] <addrl> [+l-]<addr2>
*PMemory [-BRQ] <addrl> [+l-]<addr2>
+<addr3>
Parameters
B Optionally read and display as bytes
R Read repetitively
Q Suppress output (and speed-up loop)
<addr1> Address for start of display
<addr2> offset from <addr1>
<addr3> offset from <addr1 + addr2>
Use
*PMemory is used to list areas of memory in the
target system, with syntax similar to that used by
*Memory (PRM IV).
The single-address form displays a 256 byte block of
memory starting from <addr1>.
The two-address form displays memory starting at
<addr1> and ending at <addr1 + addr2>.
The three-address form displays memory starting at
<addr1 offset by addr2> and ending at <addr1 offset
by <addr2 + addr3>>.
The repetitive functions may be used to exercise the
target's bus for hardware debugging - the R
command will start a repeated read operation on a
given address (single-address command) or range of
addresses
(multiple address command).
Note that use of the R option alters the default
address range of the single-address command from
256 bytes to a single (byte or word) operation and
also limits reporting of the data value read to loops on
which the value changes.
The Q option suppresses all output to greatly
increase the loop iteration rate.
Example
*PMemory 3800000
Displays the first 256 bytes of the MOS ROM, in
wordwide format.
Related commands
*Memory, *PMemoryA
5-10 Issue 2, June 1991 Part 5 - Main PCB fault diagnosis