> I'm trying to use a 176 pin component. Is there a way to list all the pins
> whether each one is input, output, etc. ? It's a real drag double-clicking
> one, comparing its "electrical type" to my data sheets.

As others have suggested, you can generate a report

Another possibility is to double-click on a pin, and set it to a selected
state. But *also* invoke the global editing feature so that all pins of the
*same type* are *also* selected. So if the pin you are looking at is an
input pin, *all* input pins will then be selected. Or if that pin was an
output pin instead, then all ouptput pins will then be selected, etc. Doing
this will help provide a quick indication of which pins are which.

> Is there a standard way to indicate (on paper) which pins are input and
> pins are output on a (b)-flavored schematic symbol ?

As someone else has suggested, you could "colour code" your pins. I have
done so in some instances (but not always) myself.

> Does anyone actually use the "Hi-Z" pin type ?
> David Cary

A "Hi-Z" pin is similar to an "Output" pin in that it is *never* an input
pin. However, an "Output" pin is always either logic high or logic low. A
"Hi-Z" pin differs it that it can be either logic high, logic low, *or*
(additionally) in a high impedance state. Various ICs, e.g. 74HC125
(quadruple tri-state buffer) use such pins, and I have personally created a
number of components which use such pins.

"IO" pins can be either input or output. As such, I regard such a pin as
being, in a way, a "superset" of a "Hi-Z" pin, in that the pin can *also* be
an *input* (when its associated output circuitry is in a high impedance
state). As such, there is a difference between "IO" pins and "Hi-Z" pins,
just as there is a difference between "Hi-Z" pins and "Output" pins.

I am not sure off-hand whether "Open Collector" and "Open Emitter" pins are
output-only or I/O in nature. (Can anyone answer on this one?) Maybe there
is a case for Protel to support "Output Only Open Collector", "IO Open
Collector", "Output Only Open Emitter", and "IO Open Emitter" type pins, to
support yet-better ERC checking of schematic files. (I have an idea that
someone else has already suggested this though.)

(In case you don't know, "Open Collector" pins can be either high-Z or
(low-Z) logic low, and "Open Emitter" pins can be either high-Z or (low-Z)
logic high; as I said, I don't know if they can *also* be inputs. But there
still could be a case for providing distinct types of pins, depending upon
whether each of these can also be inputs or otherwise.)

Geoff Harland.
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