IBM Series 1 User Manual page 234

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TNL: GN34-0368 to GA34-0033-0 (February 4,1977)
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Each device
attachment must have the capability to redrive or propagate
a poll as part of the serial polliny mechanism.
This
polling mechanism must
be
contained
on
that part
of
the
device attachment card(s) that plugs into the 1/0 socket.
This is to ensure that: 1) cabling delays are not
encountered,
i.e.
cabling out to the
poll
mechanism
at
the
device may cause incorrect
timing sequences
to
occur
depending
on
cable length and driving/receiving cdpability,
2) powering down a device must not affect the ability to
propagate a poll.
All
I/O
channel drivers, receivers,
dnd
logic necessary
to condition receivers should be on that
part
of device
attachment card(s) that pluys
into the I/O
socket. This
would include at least device address comparison logic, some
DPe command logic (for detecting a write sequence), and
service
qate
capture logic.
1PL
logic,
to
the extent that the attachment should
h a vet he a b iIi t
y
to hal
d.
the s tat e
0
f
the .. e nab leI
PI.
c Y c 1 e
steal
requ~sts
and transfer-s" pending device ["espouse,
should be located on that portion ot the attachment that
plugs into and derives power from the I/O
socket.
Otherwise, this may preclude the
capability
of the device to
execute a
processor-initidted
IPL in
auto
IPL mode.
For attachments to devices which are capable of exe-
cuting processor initiated IPL, at least that portion of the
IPL logic which will detect and hold the indication that the
attached device is to IPL should reside on that part of the
attachment which plugs into and takes power from the I/O
socket. (See also IPL sequence description.)
Printed Circuit Wire Lengths. Printed circuit wire lengths
between I/O channel drivers/receivers and the connector tabs
on the interfacing card should be held to
2
inches maximum.
Tag inputs and outputs, and request in lines should favor
shorter lengths.
5 i9.1E!1
.£!~.£i.!lg.
All I/O channel cireui
t
modules shoH ld
have clamping for negative excursions of the signal input.
£irf.!!i.!: Mod!!1g Voli~~~ Tolerances. Circuit modules used in
device attachments that utilize voltages from IBM supplies
must be capable of operating with ±10 percent tolerances
from nominal
as
seen at the module pins.
Ci££uil
Modul~ Ovg£YQ1!~g~.
an
overvoltage rating for
nominal.
All circuit modules
voltage
supplied
must
of 40\
have
over
Processor I/O Channel 2-73