As you are taking an interest in this CD ROM, the chances are that you already have an idea what a PICmicro is, but just to refresh your memory....

A PICmicro is a microcontroller integrated circuit device manufactured by Arizona Microchip. A microcontroller is essentially similar to a microprocessor but it additionally contains its own program command code memory, data storage memory, bidirectional (input/output) ports and a clock oscillator. Many microprocessors require the use of additional chips to provide these extra requirements; microcontrollers are totally self-contained.

The great advantage of microcontrollers is that they can be programmed to perform many functions for which many other chips would normally be required. This not only makes for simplicity in electronic designs, but also allows some functions to be performed which could not be done using normal digital logic chips - i.e. circuits for which, previously, a microprocessor and its peripheral chips would have been required.

There are many types of PICmicro microcontroller available, ranging from those which can only be programmed once, to those that can be repeatedly reprogrammed. There are two basic types of the latter: those that require an ultra-violet light unit to erase their previous data before being reprogrammed, and those that are electrically erasable.

Amongst the latter PICmicro microcontrollers is the PIC16F84 (and PIC16F84A). It is an EEPROM (electrically erasable programmable read only memory) device, which means that it can be rapidly reprogrammed as often as you wish, without the need for ultra-violet light. This ease of reprogrammability makes it ideal for the tutorials on this CD ROM and for on-board software development in the real world.

You may also have heard of the PIC16C84 device. This was the original member of Microchip's EEPROM microcontroller family, but has now been replaced by the superior PIC16F84.

The PIC16F84 (and PIC16F84A) may have suffixes, such as -04 or -10. The suffix indicates the maximum clock rate at which the chip can be used: -04 means 4MHz, -10 means 10MHz, -20 means 20MHz.

Whilst it is the 'F84 device which is referred to throughout this series of articles, the information about the commands which we present here is, in most instances, also applicable to other members of the PICmicro family, in which there are many devices, of increasing functional complexity, such as the PIC16F87x series for example.

Once you understand a PIC16F84, though, you should have no difficulty applying your knowledge to other PICmicros.