Selecting PIC chips

[The Master]

Hi, sorry but ive still not got the hang of this yet. I need 3 different types of PIC chip.

Heres what i need

Type1:-
1 switch input
1 zero crossing input (for PWM)
2 LED outputs
4 outputs to triac opto isolators (also for PWM)
2 pins for external oscillator
2 Hardware UART pins (TX not required but preferable)

Type2:-
Same as Type1 but with 4 extra outputs for triacs (8 total)

Type3:-
Same as Type1 but with another 8 outputs for triacs (16 total)

I would also like about 2 I/O pins spare on each one incase of last minute design changes. I dont want to waste too many pins though. I thought about the PIC16F88 that mister_e recommended (http://www.picbasic.co.uk/forum/showpost.php?p=53581&postcount=4) for Type1. I think that would give me 3 or 4 spare pins (depending on MCLR). I didnt really want to waste that many though and i dont have a clue for the other 2 types

[skimask]

http://www.microchip.com/ParamChartSearch/params.aspx?branchID=1002&mid=10&lang=en&pageId=74

Parametric search at Microchip's website...just start clicking items that match what you've already got, but click on more pins...
I come up with the 16F88x (3,4,6,7)
Anything else?

[The Master]

I tried using that search before but i kept getting no results. I tried just putting 1 search field in and nothing happened. I didnt notice that the search link doesnt actually show you the results.

When im looking for a chip that has RX/TX pins is that "A/E/USART" instead of "UART"? Whats the difference between them?

What is the difference between program memory KBytes and KWords?

There are 3 chips that i think would do what i need. PIC16F648A, PIC16F87 and PIC16F88. All 3 seem to be more or less the same. Is "16F88x" the same as "PIC16F88"?

[tenaja]

Your best bet is to compare all of the chips on the m'chip site. Click the checkbox on the left and then click compare (or whatever they call it). then you'll see the exact differences. Then read the datasheets and you'll learn more.

To be nice, here are a few answers...
The Enhanced UART just has more features. :)
Program memory; kbytes is the amount of physical space in the chip. Kwords is when you take the kbytes and divide it by the bits per program word. In reality, kbytes is irrelevant; you only need to know kwords.
The 16F88x series is NOT the same as the 16F88. In general, you can always tell if a chip is "the same" when they are in the same datasheet--if not, then they vary significantly enough to warrant a new sheet. You can read the datasheets to get the exact differences between the two series, but they are too numerous to list. The 16F88 series was sort of a ground-breaking chip, setting new standards for the PIC in power consumption and other features in a small chip--years ago. The 16F88x was introduced a few years later, and has more features/memory, etc.

[The Master]

I have been using the filter checkboxes. Thats probably the only part of that search that i actually know how to use.

The Kwords thing makes sense. I was reading something earlier about how some PICs have 14 bit words. I also noticed that PIC basic tells you how many words it used when compiling a program.

I found the PIC16F88 and PIC16F883/4/6/7 and filtered to just those 5. The PIC16F88x all seem to have enough pins to act as all 3 types. I think that might be why skimask suggested them. The PIC16F88 seems to be a better match for Type 1. I do want 1 or 2 spare I/O pins but i dont want to waste a lot of them. The 16F88 also has more ram than the others. Im not sure if i will need all that though. Apart from that i cant see much of a difference between them. 4 KWords should be pleanty because i normally only use about 900