I think it sounds great Ika
I've played around with VB quite a bit with regards to UART, but not with USB unfortunately..
If you keep it simple, then the raw programming of the micro will be minimal, especially if you use UART
The Logic Analyzer;
Monitor the status of the Pin and when it changes send a byte through UART with the relevant information (high/low). The VB program will display a running image with the data with its refresh rate (time scale) being changeable by the user.
The time it takes to send one byte via UART will be your smallest resolution. Its crude, but it will work for a simple logic analyzer, and will get decent speeds with a fast enough UART.
The Oscilloscope;
This will require bi directional UART, primarily for setting the time scale. Create a routine that waits for a positive zero crossover, and then grabs 256 samples and stores the data into an array.
The time between samples could be extended with NOP's or by burning cycles (as required by the user on the VB side of things). Send the 256 bytes of data to the PC, for display on the VB program. It simply maps the 256 ADC values on a graph and waits for the next signal.
Your thoughts?
Sorry about your post on my site BTW, I used Web Expressions to update the site instead of a standard ftp program, problem is, it deleted all folders that were not found locally on the computer - the forum being one of them.