This is just a simple signal tracer for the RS232 port on the Interface 1.

Theory of operation

This tool will strobe the CTS line and then wait for incoming data on the RX data line. When it collects 1024 samples, it will trace them on the screen in four successive rows and loop back. The fastest possible sample rate can be acheived by running INI instructions one after another. Each of these will take 16 T-states to run giving us an effective sample rate of 3.5MHz/16=218KHz. Timing error will therefore be +/- 8 States, or 2.286us.

Usage

Use LOAD *"b"CODE to load it, and RANDOMIZE USR 32768 to run. Pressing any key will exit. Each point is an individual sample and as the yellow markers are spaced at 8-pixel intervals they mark time divisions of 128 T-states (27.34us). Every 7th line marks 256us, so the next version will probably highlight this.

Screenshots

Version 1.0 showing some bytes coming in on the serial port at 57600bps.