Performance
Verification
Lexicon
Diagnostics
Reflex
software contain two categories of
Diagnostics:
Power
Up
Diagnos-
tics,
which
are
run
automatically
each time the unit
is
powered on,
and
User
Diagnostics, which
are
invoked
by
simultaneously pressing the
front
panel
STORE/CLEAR
and
PARAMETER/LEARN
buttons
during
power
up.
Power
Up
Diagnostics
when
power is first
applied
to
the system,
a
series
of diagnostic
tests
are
run
to
help
avoid
having
the normal
operating
software attempting to run on faulty
hardware.
When the
system
first
powers
up,
the maskable interrupt
(from
the
UART/
MIDI IN)
is disabled,
the UART
is
initialized
and
the
nonmaskable interrupt
(NMI)
is
disabled
by
toggling DlSABLEINT/from
Output
Register
2
(U5
pin
9)
low.
Nonmaskable
interrupts, which
occurfrequently (every
51
2us),
must
be
tightly controlled.
A low
on the
DISABLEINT/ line
prevents the
NMI/ line from
being pulled
low
and triggering
an
interrupt.
Once the
DISABLEINT/ line
is
low
the software
loads software into the Lexichip which
allows it
to output a
WC/
signal
at the properfrequency
(32kHz).
At this point, the software jumps to the
diagnostic section, which turns
on
all
of the
front
panel
LEDs
except the
headroom
LED for
approximately two
seconds. It turns
off
the LEDs, checks
to see
if
a
key
was pressed and then begins
running
its
tests.
At power
up the following
diagnostic
tests
are
run:
A ROM
Test
B
RAM
Test
C
WCS Test
E
Interrupt Test
Upon
completion
of these
tests,
the
SRAM
(U9)
is cleared
to
all
Os,
and the
normal
operating
software
is
run.
Pass/Fail
of Power
Up
Diagnostics
When
the
Power
Up
Diagnostics
pass,
the display
stays
blank until
the
normal
operating software
displays
the letter
L (while
the registers are
read
from
the
EEPROM),
then
the selected preset or register ID number.
If
a test
fails,
the
letter
ID
of the
test is displayed and the
test
is continuously
re-run.
To
skip
a
failing
test,
press
and
hold
the
STORE/CLEAR
and
PARAMETER/LEARN
buttons
for
approximately 1/2
second.
ROM
Test
This
is
a
checksum
test
of the system
ROM. A checksum
test
is
performed
by
reading each memory
location in ROM
and adding the stored value stored.
This number
is compared
with
the total calculated
when
the software was first
assembled.
A
mismatch indicates
a problem
with
the ROM
or
with the
Z80’s
ability
to
read the
ROM
(shorted
address
line,
etc...). The last
two memory
locations are reserved
to
store the comparison
value. In
practice,
the
ROM
test is
primarily
useful
for verifying
that the contents of the ROM
were
transferred
correctly
from
the
master
and
are
uncorrupted.
3-6
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