Service manual

Service Manual
000000 Timers failed to get to TO done, T1 not
done. Either indicate 10C cannot time
properly
other Number of wait loops expired before
failure.
Since in this test the clock signals for IOC and VIDC are
both derived from the same clock (see Fig 1-2: System
timing on page 1-2) errors in the speed of this clock will
result in the ratio remaining correct. A fault will not be
indicated, but the measured processor speed may be
abnormal.
The screen colour is restored to purple at the end of this
test.
ARM type test
The final test attempts to read the ARM 3 identification
register. If an ARM 2 is fitted, an undefined instruction
trap should be taken. This test will not be performed if
memory is faulty, since it relies on the operation of
memory for vector storage.
The test is announced with the message
ARM ID:
or
ARM ID: skipped
and the results are indicated with a message of the form
ARM ID xxxxxxxx
where xxxxxxxx may be
00000000 ARM 2 fitted
91560300 ARM 3.0 ID register content
FFFFFFFF Fault: exception not taken, no ID read.
Result reporting
At the close of the test sequence, the screen colour is
set to red if a failure has been recorded in the tests,
green if not. The test result is transmitted to the operator
by flashing the disc selection light in accordance with the
scheme described earlier.
An overall PASS/FAIL message is also displayed with
the same result code - this will be either
PASS: xxxxxxxx
Or
FAIL: xxxxxxxx
where xxxxxxxx is a bitmap summarising the test results
and other flags. The meaning assigned to these bits is
as follows:
Status bits
00000001 Self-test due to power-on
00000002 Self-test due to interface hardware
00000004 Self-test due to test link
00000008 Long memory test performed
00000010 ARM 3 fitted
Fault bits
00000200 ROM failed checksum test
00000900 MEMO CAM mapping failed
00000800 MEMC protection failed
00004000 VIDC (Virq interrupt) timing failed
00008000 Sound (Sirq interrupt) timing failed
00020000 Ram control line failure
00040000 Long RAM test failure
Only bits 8 to 31 indicate faults: any of the bits 0 to 7 may
be set with a green screen and the PASS message
displayed. Bit patterns not defined above may be
assigned to future versions of the test software.
Using the external diagnostic
interface
When this interface is attached, the target machine will
accept a small number of commands and associated
parameters which you can use to exercise memory and
peripherals, examine memory or peripheral registers, or
even load test code into the target machine for remote
execution.
In order to be able to test the target machine using this
interface, you need the following:
• a host computer (ie an Archimedes computer fitted with
a standard Acorn User Port podule) that boots up from
the floppy disc drive by default. You can configure this
with the *Command *Configure drive 0
• a display adaptor
• a test disc
• an interface cable.
To use the external diagnostic interface, proceed as
follows:
1 Open the compartment on the rear of the display
adaptor to reveal the 20-pin IDC connector and cable.
2 Plug the IDC connector into the user port on the host
machine.
3 Connect the interface cable to the 9-way D-type socket
on the display adaptor.
4 Connect the other end of the interface cable to the test
link LK4 on the target machine
5 Place the test disc in the floppy drive on the host
machine.
6 Switch on the host machine, so that it boots up using
the test disc.
7 Switch on the target machine.
You are now ready to test the target machine. Software
support for the external test interface is currently provided
by a RISC OS relocatable module called Probe, which
provides a set of SWIs corresponding to the low-level
interface commands and a set of *Commands modelled
on the RISC OS *Debug commands. The following pages
contain information on these *Commands.
Part 5 - Main PCB fault diagnosis Issue 2, June 1991 5-9