Intermittent Process Check - IBM 5100 Maintenance Information Manual

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\
/
i
\