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much as possible, and always touch the chip's container or
surface which it is touching before picking up the chip.
Also touch a surface or container before placing the chip
back in it.
Touch the soldering iron to the work surface or to a small
piece of metal foil on the work surface before touching it
to the PC board for soldering.
chip is not the path for any static discharge.
insertion as the last steps in assembly to avoid unnecessary
exposure.
POLARITY
Many electronic components will not work if they are connected
backwards.
way only will have a mark of some sort to indicate which way
is which.
corresponding mark at each place, or an indication that all
such components go the same way as a marked "typical" one.
I.C.'s
All I.C.'s must be inserted with pin 1 in the correct location
to avoid damaging the I.C.
by several different marks.
square notch in the center of the end near Pin 1.
common one is a slightly depressed or raised dot in the
corner of the chip next to Pin 1.
always be present to indicate Pin 1.
other circular markings on the centerline of the chip, usually
towards one or both ends; these should be ignored.
is some kind of Pin 1 mark on the bottom of the chip also.
(Note:
Many I.C.'s have a code for date of manufacture which
is a 4 digit code.
the 25th week of 1974.
number.
The code will be alone, the device number will have
manufacturer-dependent suffixes and prefixes,
is a 7404 type chip.
will be found, such as a square pad, a dot, an arrow showing
Pin 1 direction with the note "typical"
on the board face the same way), or similar mark.
24
Touch a PC board before inserting the chip.
Any component which it is important to insert one
The board where they go will have some sort of
e.g. 7425 would indicate manufacture in
Do not confuse these with the device
On the PC board, some Pin 1 indication
IMSAI 8080 System
General assembly Notes
In general, make sure the
Pin 1 is indicated on the chips
The most common is a rounded or
One or both of these will
Sometimes there are
(indicating all chips
Save MOS IC
Another
Often there
e.g., SN7404N
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