[Lowfer] TAG and Bill

[Stewart Nelson]

Hi Eric and all,

PICs have different kinds of program memory, depending on the model:

ROM -- Mask programmed at the factory.  Least expensive for large
  production runs, but high setup fee makes it impractical for amateurs.

OTP -- Can be programmed electrically, by the distributor or user, but
  only once.  Suitable for projects where you trust the code and don't
  expect to modify it.

EPROM -- Programmed electrically; can be erased with UV and programmed
  again.  The long erase times are a nuisance, and the quartz window
  makes the part more expensive.  Becoming less popular.

Flash -- Can be electrically erased and reprogrammed many times.
  The 16F84 used by the picfun timer is flash based.

See the Microchip site at http://www.microchip.com/ for details
on available parts.

Some distributors will program chips for a couple of bucks, but if
you want to experiment with the code, you will need your own
programmer.  One that will do the 16F84 and a few other types
can be had for less than $20.  See
http://hacker.instanet.com/PicPrgrKits.html .  For about $100, you
can buy a unit that will program many kinds of parts from many
manufacturers.  You can also find designs on the Net for simple
homebrew programmers that cost less than $10 in parts.

Good luck and 73,

Stewart KK7KA


----- Original Message ----- 
From: "Eric Smith" <eric@willow.nutstreet.net>
To: <lowfer@mailman.qth.net>
Sent: Sunday, February 09, 2003 7:33 PM
Subject: Re: [Lowfer] TAG and Bill


> Hmmm... you know, I've never used a PIC before, and I've long wanted to.  
> That page was all 
> non-english characters to me (no windows computers) but I think I can do 
> one anyway.  I did quite a bit of assembly language programming in the 
> late '70s (8080, Z80) and it looks like their simple risc instruction sets 
> are easy.
> 
> What do you do -- write the code, and then they burn it for you that way 
> (hope you don't have any bugs :)  ?