However, the notion of cost is an issue. For persons in developing nations to be able to do the simple Vcc sampling that is under discussion, the instrument must cost less than, say, $15US. Even that would be burdensome to most.

I've seen no PC-scopes using USB or any other transport mechanism that cost so little. One alternative would be to use something the third-world developer is likely to have on available, namely some sort of MCU evaluation board, hopefully with an on-board ADC. That would address the problem, provided the eval board was not the system under examination.

It would be nice if you could provide a link to a PC-based 'scope that had software that was freely downloadable, along with the documented file format(s) to which you refer.

RE