Where is pin 1?

I have a DIP chip that has a notch on one side and a big dot on another (opposite) side. I am a little bit confused as to where pin 1 is. I think that it's to the left of the notch, if I hold the notch upwards, but I am not sure. Why s there a dot if there is also a notch?

bottom view, pin 1 is clock wise to the notch most likely.

Manufacturer and part number?

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

void _-void-_ in the obvious place

Look in the data sheet- this will tell you.

I can't imagine what you mean. Scan it and post in abse perhaps ?

In the meantime get the data sheet ! What is the part btw ?

Graham

That's a really obtuse answer ! Who looks at the bottom view ? Will the markings be visible from the bottom ?

Graham

It has been a standard since the 1930s.

Octal valve pins were counted clockwise from the spigot, later all-glass vales were counded clockwise from a pip or a missing pin. It made sense if you were looking at the valveholders on the underside of a chassis.

When ICs were introduced, exactly the same system was use - but some manufacturers began to confuse the issue by printing the diagrams as anti-clockwise viewed from above. It still made sense from the underside of a printed circuit board, the designer and serviceman just had to remember that the data book was printed backwards.

On a lot of IC packages, the pisition of Pin 1 *was* marked so it could be seen from the bottom (e.g. a notch in one end of the package, from which you count clockwise).

Sounds as though they are still keeping to the standard.