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Mactronics :: Parallax Basic Stamp
The Basic Stamp is a microcontroller made by Parallax. The Basic Stamp is an interpreter for P-Basic a dialect of BASIC. The stamp is a very cost effective and flexible. Most important you can program the Basic Stamp from your mac thanks to Murat's MacBS2 application. The low cost and simplicity make the stamp perfect for many prototyping and control applications.

The Basic Stamp is made up or the Interpreter IC, a 256 byte EEPROM that holds the tokenized P-Basic code and a 4MHZ resonator. The development boards also include a breadboard for prototyping. You can get development boards with a serial or USB interface.

The stamp is programmed in our simple P-BASIC language. The language includes familiar instructions, such as GOTO, FOR...NEXT, and IF...THEN, as well as SBC instructions such as SERIN (serial input) PWM, and BUTTON. Each instruction takes 2-3 bytes of EEPROM space, resulting in a maximum program size of 80-100 instructions. Programs are executed at the rate of about 2000 instructions per second.

To program the stamp you will need Murat's MacBS2 and a USB to serial adapter for boards with a serial interface. MacBS2 works with Keyspan's adapters USA28 and USA19, you may also use adapters with the FTDI's FT232 chipset (more info).
Here is some info on some stamps. This info is taken directly from Parallax site.
The BASIC Stamp 2 is a 24-pin DIP (Dual inline package) module. Most commonly referred to as a microcontroller, on occasion you may see it being called a single board computer since it has its very own processor, memory, clock, and interface (via 16 I/O pins). The BASIC Stamp essentially serves as the brains inside of electronics projects and applications that require a programmable microcontroller.

Processor Speed: 20 MHz, Program Execution Speed: ~4,000 instructions/sec. RAM Size: 32 Bytes (6 I/O, 26 Variable), EEPROM (Program) Size: 2K Bytes, ~500 instructions, I/O Pins: 16 +2 Dedicated Serial, Voltage Requirements: 5 - 15 vdc, Current Draw at 5V: 3 mA Run / 50 µA Sleep, PBASIC Commands: 42, Size: 1.2"x0.6"x0.4"
The BASIC Stamp 2px module (BS2PX24) is the highest performing of all the BASIC Stamp microcontrollers, running nearly 1.6 times faster than the BASIC Stamp 2p. The BS2px includes a built-in voltage comparator, as well as user-configurable Pull-up Resistor, Schmitt Trigger, and Logic Threshold circuitry on every I/O pin.

Processor Speed: 32 MHz Turbo, Program Execution Speed: ~19,000 instructions/sec., RAM Size: 38 Bytes (12 I/O, 26 Variable), Scratch Pad RAM: 128 Bytes, EEPROM (Program) Size: 8 x 2K Bytes ~4,000 Instructions, I/O Pins: 16+2 Dedicated Serial, Voltage Requirements: 5 - 12 vdc, Current Draw at 5V: 55 mA Run / 450 ?A Sleep, PBASIC Commands: 61, Size: 1.2"x0.6"x0.4"
Tutorials and Related Links

The BS 2 does not have Analog to Digital functionality, but we can achieve similar functionality with a Resistance and Capacitance circuit. BS2 has an RCTime that returns the time it takes a capacitor to charge through a resistor. Here is a tutorial about RCTime.
http://www.emesystems.com/BS2rct.htm

Basic Stamp FAQ by Al Williams. Link last checked on Nov/11/05
http://www.wd5gnr.com/stampfaq.htm

Basic Stamp Tutorial. Link last checked on Nov/11/05
http://www.phanderson.com/stamp/tutorial.html

Basic Stamp Programming
http://www.reflections.co.nz/home/micro/Software/Stamp-detail-incl-instr-set.htm

Basic Stamp Tutorial
http://www.mines.edu/Academic/courses/physics/phgn317/lab8/Lab8_02.htm

Basic Stamp Support by EMC
http://www.emesystems.com/BS2index.htm

Basic Stamp Web-Ring
http://www.webring.org/cgi-bin/webring?ring=stamp;list
Here is a list of some good books that I own and recommend:

Data Acquisition Techniques Using PCs (Good)
Build Your Own Low-Cost Data Acquisition and Display Devices (The code is in pascal, no disk/website with source code, yet is really good)
PC Interfacing and Data Acquisition : Techniques for Measurement, Instrumentation and Control
Find more books...