AVR-Chat

techy fellow wrote:
> Thanks alot for the fast reply. I managed to buy a discarded portable
> hand-held device (I think it is for entering of PINs) real cheap. My
> intention is to savage whatever is in there. The main item I'm
> looking at is the 2 X 16 LCD panel (no back light). But I spotted
> this chip on the PCB. Thought if I can make use of it, I will buy
> some more. It cost about USD 3.80 per piece and it is considered
> cheap even for the LCD itself. In singapore, the same LCD cost about
> USD 7.80 when new.


The 87C530, look for the "7" in the "87", this "7" means with internal
customer programmable code memory.

In the old days, anything with "7" means an eprom, like the 27Cxx (for eprom
chips), 87C51 (for the 8051 with internal eprom), etc.   Being a 87XXX it
means the chip comes out of the factory with the memory all "FFh", and it
would be programmed by the customer.  It has a real eprom inside, the
difference is if it has a crystal window or not.

With the crystal window, you could erase the eprom (by using UV light) and
reprogram again and again.  Crystal window (not glass) requires mechanical
physical protection for installation, so the chip NEEDs to be done in
ceramic.  Without the crystal window, the chip can be made in plastic, thus,
lower cost, but then, once programmed the chip can't be erased, so the name
OTP (one time programming).  Both versions, with the window or not, will
have the same prefix "87C530", they are EXACTLY the same inside, if you
could poke a hole over the OTP chip and expose it to UV it would erase, and
would be programmed again, but chances are you would damage the chip.

Wagner Lipnharski - email:  wagner@ustr.net
UST Research Inc. - Development Director
http://www.ustr.net - Orlando Florida 32837
Licensed Consultant Atmel AVR _/_/_/_/_/_/
December 26, 2003 12:34 pm