OTP means One Time Programmable. Can only program once because the EPROM window has been covered up by the manufacturer.

In-Circuit Serial Programming(ICSP) is when you can program the target device serially while it is still in the circuit(you need to isolate a few pins). On the PIC16F84 you only need 5 pins to program it serially. Check the data sheet for the particular device you are using.
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PIC website with other cool info.
www.geocities.com/researchtriangle/lab/6584
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Steve Kosmerchock
Engineering Technician
CELWAVE
Phoenix     AZ        USA
email:   steve.kosmerchock@celwave.com
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---- PICLIST(a)MITVMA.MIT.EDU's Message ----

IĞm really new in the WorldĞs PIC but I ever want to know every detail
about what IĞm learning.  IĞve read some Data sheet from Digikey and found
some terms like:

        1. - In-Circuit Serial  Programing, What is this?

        2. - In the data sheet exist a camp that say:  "Configuration" , some PICs
are EPROM and some other PICs are OTP.  I think That the EPROM ones can be
programmable but What is the mean of OTP ?

        Somebody can help me please ?  IĞll be very glad...