I love the PIC16F505 chip.  I've used it successfully in many designs.  Careful 
to not count 12 Output lines, it only has 11 I/O and 1 Input only.  The other 
sad thing I remember (please correct me if I'm wrong) is the internal 
oscillator is only 4Mhz.  To get 20Mhz operation, you must use an external 
oscillator.  I don't like the VCC pin 1, Gnd pin 14 either.

J.


>An outside of the box idea is a PIC 16F505 has an internal osc, 14 pin DIP 
>with 12 usable I/O lines and you only need 11 of them. And its about half the 
>cost around 75 cents in bulk.  So program it, slap the power leads on, and it 
>does its thing.

True, a GAL can process I/O ten million times faster than the eye can perceive, 
whereas the PIC running a tight loop and simple table lookup might only be able 
to process a hundred thousand times faster than the eye can perceive.  Fast 
enough for human I/O devices, although not for memory decoding.

Something I dislike about Microchip is they never hook up GND to pin 7.  If 
they did, you could program up a couple of their processors to emulate many TTL 
logic chip at up to "hundreds of KHz" speeds just by loading a simple program 
into the PIC.  I need a 7400.  No wait I need a 7402, I'll just reprogram it.  
That doesn't work because Microchip always wires GND to pin 1 or something 
inconvenient like that.  Doesn't matter for a new design, only if you're trying 
to make a "7447 replacement" (other than that being a 16 pin, obviously)





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