Hi,
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Well what do you whant exaclly, because there are many types of boards !!
You have the Carrier Board and The BOE (Board of Education), and another one that i don't remenber the name.
Anyway if you are a begginner with the stamp you could use a breedboard, the stamp only requires one reset switch wich is not even critical and 4 or 3 pins to conect to the PC, you can make your own cable and conect it to the breedboard like that you don't even need to buy or make any board and the breedboard lasts 4ever !! $$$
And their boards are very antiquated !!! Later you can build one for yourself with newer memory ic's they offer 2Kb lol and you can get one Serial with 128K at microchip.com, and perhaps and RTC (Real Time Clock) wich is very usefull or a Temperature Sensor, all in SMD taking less size than the Stamp itself lol
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And remember that the I/0 pins of the stamp can't provide more than 25 mA, nor the PORT can take more than that i think, be caerfull when driving high current periperals to the ports or you will end up with the STAMP's PIC wasted !! And should i remember you that a STAMP is rather expensive !!!!! I know i have one too !!!!!!