What is the ISO symbol for a NOR logic gate

Question

What is the ISO symbol for a NOR logic gate

wolf33055 (Mechanical)

(OP)

1 Dec 03 05:16

I've spent the last two hours looking on the internet, can anyone tell me what one looks like. it must be the ISO symbol.

Thanks

Chris

zeitghost (Computer) · Answer 1 · 2003-12-01 07:13:02

It is undoubtedly some fatuous rectangular box with a nonsense symbol inside it.

Unfortunately, my quick look in my library only reveals mil std symbols that people can understand.

rgds
Zeit.

zeitghost (Computer) · Answer 2 · 2003-12-01 09:42:40

According to this

http://www.cs.man.ac.uk/teaching/electronics/CS121/manu...

the normal symbol is ISO.

If true, I'm amazed.

(search the pdf for ISO).

rgds
Zeit.

tsection (Electrical) · Answer 3 · 2003-12-01 10:37:35

Yer I think the symbol your looking for is the 'fatuous rectangular box' with a "1" in it, this implies an OR gate then with the usual smal circle on the output pin that would imply the output is NOT'ed.

At lest this is a valid symble for a NOR gate in my old collage notes.

BrianG (Military) · Answer 4 · 2003-12-02 03:35:36

Just like Zeit I thought it would be a boring box symbol, however I decided to check our on-line Standards database for all available publications on logic symbols.

Apart from the expected MIL, IEEE and ISA standards, for new or recent standards there was only a British Standard BS-5070-4(1990) and two Dutch NEN NPR5156 and NPR5157.

I did find one ISO standard ISO-5784-2 (1989) but this is for fluid logic devices, not electronic ones. So, as there does not appear to be an ISO standard why not use the original MIL ones!

Skogsgurra (Electrical) · Answer 5 · 2003-12-02 04:22:00

I have seen them all and this is how I remember the different logic symbols:

There are three common "families" of logic gate symbols: the ISO, the IEEE and the DIN families.

The ISO - which I peronally think is the original - uses modified "half-circles" with the output to the right and the inputs to the left. There is a difference between AND inputs and OR inputs; the AND gates have a straight vertical line where the inputs land and the OR gates have a curved line, like a ")". There is another difference between AND and OR, the OR gates had a more "pointed" half-circle, but there is some dispute about how pointed it really was or should be.

The NOT function which turns an AND into a NAND and an OR into a NOR is handled by output negator (a small circle at the output). The XOR has two curved lines "))" on the input. More complex functions like counters, flip-flops etcetera use boxes with letters that clarify the function.

The IEEE symbols are all boxes with symbols that describe their functions. The AND has an "and" symbol "&" and the OR has a symbol that says that "one or more" of the inputs shall be true for a tru output. The symbol for "one or more" is = and > combined (cannot find the symbol on my keyboard). The XOR has just a "1" inside the box since an XOR produces a true output when only one of the inputs is true.

The DIN symbols were similar to the ISO symbols, but they all looked like the ISO AND gate. The difference between AND and OR is that the inputs stop at the vertical input line for an AND and go all the way to the semi-circle to the right for an OR. There was an extra vertical line at the input for the XOR. The NOT was a circle or a dot at the output (or input, if needed).

wolf33055 (Mechanical) · Answer 6 · 2003-12-02 08:50:50

Thats great.

I thought it was the curved type not the square type.

Where this has all come from is i had an contral exam the other day in which i was asked to draw an iso symbole for an NOR gate. I drew the curved one but my notes say its the box type with the greater or equal to sign.

I would like something that i can print off or even the relevent iso number if posable

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What is the ISO symbol for a NOR logic gate