In SX Microcontrollers, SX/B Compiler and SX-Key Tool, phipi wrote:

A big consideration is how to program the chip once it's soldered in place. Using an SX, this is particularly easy using the crystal pins and the SX Key. You hardly have to design aroound the programming, save for possibly a jumper to disconnect the crystal. With a PIC it's a lot more complicated. You either have to use high-voltage programming or sacrifice a pin to enable low-voltage programming. In any event, programming is done through port pins that may not be connected conveniently for this purpose.

An alternative that I've used in several designs where size is an issue and/or an A/D converter is needed is the Atmel AVR, specifically the ATTINY13. This is an 8-pin device available in an SOIC that has an internal 9.6MHz clock. It sells for $0.81 in hundreds. Although programming is done through three port pins, plus the reset pin, the serial algorithm is very simple. I use a BASIC Stamp to program these parts once they're on board, via a short cable and a spring-loaded test clip to grab the AVR from both sides. An AVR is nothing like a PIC or SX, though. The instruction set and architecture take some getting used to.

-Phil

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