Intermittent
Process
Check
Use the following procedure
to
help you find the cause
of
intermittent process checks:
1. Before resetting the
PROCESS
CHECK light, refer
to
Error Checking in Section 4
of
this manual. This
provides a list
of
lines you may probe
to
help
isolate the process check error to a card or a
device.
3-82
Use the following probe points and card
references, along
with
the 5100 logic diagrams
and MAPs
to
isolate the process check error:
•
Rd
data error
(-G2-S08)
- This is a parity error
on
data in the read data register
of
the
controller. Cards that can cause this error are:
the controller
(G2)
card; the display (J2) card;
the BASIC,
I/O,
and diagnostic (H2) cards: the
read/write storage (K2,
K4,
L2,
L4,
M2, M4,
N2, and
N4)
cards; and the APL supervisor (H4)
card. A parity error, resulting in
an
Rd
data
error, occurs
if
there is
an
attempt to read from
a read/write storage address
for
which the
read/write storage cards
are
not installed. This
means that
if
less than 64K
of
read/write
storage is installed,
an
error
in
the
microprogram can cause a process check.
• Bus
in
error (+G2-U09) - This error is a parity
check
on
bus in. Cards that
can
cause this
error
are
the controller
(G2)
card; the base
I/O
(F2)
card; the
ROS
adapter
(E2)
card; the
expansion feature (B2) card; and the
I/O
cable
driver (A2) card.
In
addition, this error can be
caused by the following
I/O
devices: keyboard,
tape unit, printer, or Auxiliary Tape Unit.
To determine the device address, probe the
following address line points and refer
to
the
following chart:
XO
F2-007
X1
F2-B07
X2
F2-009
X3
F2-002
YO
F2-B09
Y1
F2-01O
Y2
F2-B10
Y3
F2-011
Note: An active line will
have
a + voltage level.
Device
Address
Address Lines Device
Name
o
2
3
4
5
6
7
8
9
10
11
12
13
14
15
XOYO
XOY1
XOY2
XOY3
X1YO
X1Y1
X1Y2
X1Y3
X2YO
X2Y1
X2Y2
X2Y3
X3YO
X3Y1
X3Y2
X3Y3
Controller G2
Nonexecutable
ROS
(BASIC C4 and APL
ROS
C2,
02, 04)
Not
assigned
Not
assigned
Keyboard and the
APL-BASIC switch
Printer
Not
assigned
Not
assigned
Expansion feature
Not
assigned
Not
assigned
Not assigned
Not
assigned
Not assigned
Tape units
All
I/O
• +Address check (F2-B13) - This is a device
address check on the base
I/O
(F2)
card. The
base
I/O
(F2)
card and the controller
(G2)
card
can
cause
this error.
• +Address check,
ROS
adapter (E2-010) - The
device addresses are checked at the
ROS
adapter
(E2)
card and the error can be probed
there.
• +Address check, expansion feature (B2·J13) -
The device addresses are checked at the
expansion feature (B2) card and the error can
be
probed there.
• +Address check, printer (A2-P12) - The device
addresses are checked at the printer adapter
card and the error can be probed there.
• +Address check, auxiliary tape (C1-P05) - The
device addresses are checked at the auxiliary
tape adapter card and the error can be probed
there.
Only one
of
the device address lines
XO,
X1, X2,
or X3, and only one
of
the device address lines,
YO,
Y1, Y2, or Y3 will be up when a device is
addressed. The device address check, occurs
when any odd number
of
the eight lines is up
when a device is addressed.
r\
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