Debbie,
The 877 devices are characterized by their maximum operating frequency.  
The 877A devices are all dc to 20 megahertz.  The 877 and 877A use 
different programming algorithims which isn't a big deal since you are 
using a PS+ programmer. 

I like the 877A and have put over 2000 in the field without incident.  I 
also like tiny bootloader and use it with my non comercial projects.

Bill

cyberia429-piclist@yahoo.com.au wrote:

>Picers - I need to buy a few 16F877's/F877A's but I'm somewhat confused by the
>options. A company like, eg Futurlec offers the following :-
>
>http://www.futurlec.com/
>
>PIC16F877-04/P 	PIC16F877 Flash 40-pin 4MHz 8kB Micro 
>PIC16F877-20/P 	PIC16F877 Flash 40-pin 20MHz 8kB Micro. With A/D PIC16F877A-I/L
>	
>PIC16F877A Flash 44-pin 4MHz 8kB Microcontroller (??) 
>PIC16F877A-I/P 	PIC16F877A Flash 40-pin 4MHz 8kB Microcontroller 	
>
>For starters, 44 pin is no good 'coz I use a 40 pin Picstart+
>
>What's this 4Mhz vs 20MHz? There's no mention of different speed limits in my
>PIC16F87X Microchip data sheet - they're all DC to 20MHz, aren't they?  	
>
>I'm only in the xptal stage - doing LCDs, starting out on I2C, ADC  & stuff
>like that. Would anyone be willing to offer advice on what I should go for?
>Especially any gotchas v/v the F877A? 
>
>Thankz if can help - Debbie :)
>
>Find local movie times and trailers on Yahoo! Movies.
>http://au.movies.yahoo.com
>  
>

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