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Re: gEDA-user: Introduction and some questions/thoughts on gEDA/gaf...



On Tuesday 13 September 2005 10:29 pm, Stuart Brorson wrote:
> > [snip]
> >
> > >Sorting chips by function (opamp, regulators, microcontrollers..) should
> > > be better since manufacturers of some chips change but the names are
> > > preserved. For example old uA723 is now made by Texas and not by
> > > Fairchild who introduced the prefix uA (originally "micro"A) in 1970's.
> > > Some popular chips can have many manufacturers, so it will make the
> > > problem where to put them.
> >
> > 	Hmmm.  An interesting idea.  Currently, there are directories
> > (like micro or tube) which are exactly this.  Does this really scale?
> > What do others think of this?
>
> Designing an optimal parts library is more difficult than one
> might think at first blush.   On one hand, there are lots of parts
> which aren't associated with any one particular manufacturer, such as
> passives, common diodes (1N4148), transistors (2N2222)  or (showing my
> age) many common vacuum tubes.    On the other hand, it's logical to
> organize other parts by manufacturer.  Examples which spring to mind
> are MicroChip PICs, Intel microprocessors, or speciality parts such as
> the MAX232.

Stuart is right on target in my opinion. Further, this problem seems to know
no bounds (Except with most FPGA's). For example, Glue logic chips like 
ttl/cmos, ecl, bus drivers and low voltage chips are a problem. Taking only 
the LV (Low voltage) family:

74ALB		 Advanced - Low Voltage - BiCMOS 
74LV (U)		 Low	Voltage (Unbuffered output) (CMOS)
74LVC (R) (U)	 LV - CMOS (damping Resistor)(Unbuffered output)
74LVCH		 Low - Voltage - CMOS - bus Hold
74ALVC		 Advanced - Low - Voltage - CMOS
74LVT (R)	(U)	 LV - TTL (damping Resistor(Unbuffered output) (BiCMOS)
74LVTZ		 Low - Voltage - TTL - High Impedance power-up
74ALVC (R)	 ALV - CMOS (bus Hold) (damping Resistor)
74ALVCH		 Advanced - Low - Voltage - CMOS - bus Hold
74LCX		 LV - CMOS (operates with 3v and 5v supplies)
74VCX		 LV - CMOS (operates with 1.8v and 3.6v supplies
74CBTLV		 CBT - Low Voltage

Now, add part numbers to the above list. Part numbers that are shared
by just about *all* of the manufacturers of chips in the LV family.  Also, I'm 
not going to waste bandwidth naming the different manufacturers just in
the LV series of logic - Lets just say the number of manufacturers is 
*mind boggling*.

Regards

Marvin

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