Specifications

mikroElektronika | Free Online Book | PIC Microcontrollers | Introduction: World of Microcontrollers
drawers. Suppose, the drawers are clearly marked so that it is easy to access any of them. It is easy enough to find out the contents of the
drawer by reading the label on the front of the drawer.
Each memory address corresponds to one memory location. The content of any
location becomes known by its addressing. Memory can either be written to or read
from. There are several types of memory within the microcontroller.
Read Only Memory (ROM)
ROM (Read Only Memory) is used to permanently save the program being executed. The size of a program that can be written depends on the size
of this memory. Today’s microcontrollers commonly use 16-bit addressing, which means that they are able to address up to 64 Kb of memory, i.e.
65535 locations. As a novice, your program will rarely exceed the limit of several hundred instructions. There are several types of ROM.
Masked ROM. Microcontrollers containing this ROM are reserved for the great manufacturers. Program is loaded into the chip by the
manufacturer. In case of large scale manufacture, the price is very low. Forget it...
One Time Programmable ROM (OTP ROM). If the microcontroller contains this memory, you can download a program into this memory, but the
process of program downloading is a “one-way ticket”, meaning that it can be done only once. If an error is detected after downloading, the only
thing you can do is to download the corrected program to another chip.
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