The BASIC Stamp is a microcontroller with a small, specialized BASIC interpreter (PBASIC) built into ROM. It is made by Parallax, Inc. and has been popular with electronics hobbyists since the early 1990s.
The end result is that a hobbyist can connect a 9 V battery to a BASIC Stamp and have a complete system. A serial connection to a personal computer allows the programmer to download software to the BASIC Stamp, which is stored in the onboard non-volatile memory device: it remains programmed until it is erased or reprogrammed, even when the power of the stamp is removed. If the power is reconnected the stamp immediately starts executing the program in slot 0 (of 8, numbered 0..7).
The BASIC Stamp is programmed in a variant of the BASIC language, called PBASIC. PBASIC incorporates common microcontroller functions, including PWM, serial communications, I²C and 1-Wire communications, communications with common LCD driver circuits, hobby servo pulse trains, pseudo-sine wave frequencies, and the ability to time an RC circuit which may be used to detect an analog value.
Once a program has been written in the 'Stamp Editor', an integrated development environment (IDE) in Windows, the syntax can be checked, tokenized and sent to the chip through a serial/USB Mini-B cable, where it will run.
There are currently four variants of the interpreter:
The BS2 sub-variants feature more memory, higher execution speed, additional specialized PBASIC commands, extra I/O pins, etc., in comparison to the original BS2 model. While the BS1 and BS2 use a PIC, the remaining BASIC Stamp 2 variants use a Parallax SX processor.
A number of companies now make "clones" of the BASIC Stamp with additional features, such as faster execution, analog-to-digital converters and hardware-based PWM which can run in the background.
The Parallax Propeller is gradually accumulating software libraries which give it functionality similar to the BASIC Stamp; however, there is no uniform list of which PBASIC facilities now have Spin equivalents.
A Basic Stamp 1 can be seen as part of the bomb installed in a soda machine in the 1998 film The X-Files