Horizon Grounding - NorthStar HORIZON Manual

appropriately configuring the 16-pin Interrupt header at location
lAo See the schematic drawings for details. Also, see the
Motherboard Control Byte section for programming details for
arming and disarming interrupts.
Note that interrupts during disk activity can cause detected read
errors as well as undetected write errors. Therefore, it is
recommended that interrupts always be disabled during use of the
disk (s) .
HORIZON GROUNDING
Improper grounding of a complete HORIZON computer system can
adversely affect reliablility as a result of ground noise. A
complete system is properly grounded if chassis ground and signal
ground are connected together in one place only. Therefore, the
following grounding procedure is recommended.
1. Connect the HORIZON chassis to signal ground by soldering a
jumper wire between the two holes of the location C47 at the
extreme left rear corner of the motherboard. If the HORIZO~
is being used in an environment where static electricity is
a problem (e.g. synthetic fiber rugs or dry weather), then
install a .047 ceramic disc capacitor at location C47
instead.
2. Be sure that chassis ground and signal ground are not
connected on each piece of external equipment connected to
the HORIZON. Examples of external equipment are a CRT
terminal, a printer or a third disk drive.
3. For shock protection, be sure that the chassis of each piece
of external equipment is grounded by using a 3-wire power
cord or by connecting it to the HORIZON chassis with a wire.
Note that the HORIZON chassis is grounded with a 3-wire
power connection.
North Star HORIZON Computer
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