IBM Series 1 User Manual page 255

TNL: GN34-0368 to GA34-0033-0 (February 4,1977)
DPe ADAPTER DESIGN CONSIDERATIONS
The DPe
adapter feature
is
used
in
applications requ1r1ng
access to the processor I/O channel. It does not provide
cycle steal capability. Therefore it
is
limited to direct
program control applications.
The overhead attributable to the DPC adapter, given
that all user device delays on the DPC interface are zero is
2.5 microseconds maximum added to the execution of the
Operate I/O instruction.
Recommended
input dri ver:
Requirement:
Input
terminators:
TTL
open collector
Down
level:
+0.6
volt maximum
w
42 rnA;
minimum
current required at
down level, 42 mA
iJ)
+0.6
volts
150 ohm dnd 300 ohm divider network to +5 Vdc
± 10%;
effective
termination impedance
equals
100
ohms
)21£.
Because this interface is non-isolated, it is
important
to
ensure that
there is
a
good ground
connection
between the OEM device
being attached and the card file
containing the DPe adapter
feature card.
If
there is not
a
good ground
connection,
a
large
common-mode
voltage may
be
developed, and damage
to
the
device
or
feature
card
could
result.
The
performance
of this
interface may
be affected
by
noise.
Appropriate arc
suppression,
noise
filtering, etc.,
may be necessary on the
user's inputs.
The DPC
adapter
should be connected to a device
with a
maximum of
6. 1
m
(20 ft)
of twisted-pair cable.
Attachments
to the
top-card connector
must
use a polarized Berg1 housing
part
number 65405-013
(or equivalent) and
a
contact part
number
of 75598-003 (or
equivalent)
with 124 AWG wire.
The
cable to
the
customer access panel
feature
can
be
made using a 160-pin male connector block, Amp2 part number
20279g-2
(or equivalent), male contacts Amp
part
number
66101-1 (or equivalent), and 424 AWG wire.
The
DPe adapter
card
connector
pin
assignment
for
ground
points
should
be followed at the device end of the
cable.
Diagnostic wrap capability is provided at all the DPC
adapter feature connection points for devices.
1Berg Electronics, Division of E.l. duPont de Nemours, Co.
2Amp, Incorporated
6-22
GA34-00]]
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