The New Parallax BS2-SX

copyright, Peter H. Anderson, Baltimore, MD, Nov, '98


Parallax caught many of us by surprise in offering the BS2SX which is 2.5 times faster than the BS2, adds 63 bytes of scratchpad RAM and adds seven blocks of 2048 byte memory.

This is not the BASIC Stamp 3 that we have all been waiting for. I guess we all have our wish list for the Stamp 3. Mine includes A/D, access to a real time clock/counter and an interrupt capability.

The BS2SX doesn't have these features, but I am impressed with the added scratchpad RAM and increased program ROM and the fact that Parallax managed to do this with little perturbation in the use of this new product to current BS2 users. Certainly, for those needing the extra speed, RAM and ROM, the modest increase in price is well worth the money.


I now the BS2-SX in stock. The price is $59.00. It is 15 percent less for people who qualify for the Parallax "Stamps in Class" Program.

Power Requirments.

The power requirements are a bit different for the BS2SX and if you order from us, we will include a voltage regulator package which provides nominally +6.4 to terminal 24 of the BS2SX and also +5VDC for powering your peripheral circuitry. This is discussed in greater detail below.

Documentation and Software

Parallax has both software and documentation for the BS2SX on their web site. Click on the "software" and "documention" buttons at the Parallax Site.


The BS2SX is a BS2 which is 2.5 times faster and provides eight 2048 program EEPROM blocks and 63 scratchpad bytes which may be used for temporary storage or for communicating between processes. Writing to scratch pad, reading from scratch pad and spawning a new process are implemented using the PUT, GET and RUN commands. There are also some changes in the time critical tasks; e.g., COUNT, SEROUT and SERIN.

Aside from the power requirements, the BS2SX is pin for pin compatible with the BS2.

Currently the BS2 provides a very low dropout regulator which permits the user to power the Stamp with a wide range of voltages from 5.0 V up to ??? on terminal 24. It appears this is limited to 6.0 to 9.0 VDC on the BS2SX.

For anyone buying the BS2SX from us, we offer a free regulator kit.

This kit consists of two 7805 regulators, capacitors, diodes and resistors and drawings. One regulator is configured with two series diodes between the common and ground so as to provide +5.0 plus 2 diode drops = 6.4 VDC to power the BS2-SX. The other regulator is configured in the normal manner so as to provide a source of +5VDC for your peripherals. This avoids using the on-board regulator on the expensive BS2-SX to power external circuitry.

You can then power this with any wall power unit in the range of 9.0 to 16.0 VDC. You probably have half a dozen laying around. If you don't, we have a unit which will power the regulator circuitry and also may be used to drive steppers, solenoids and the like at up to one amp. This is $6.00.

Detailed Information

I have tinkered with this new device for a few days. The following are some of my observations. I will add to them as I can.

Happy Tinkering.