I'm trying to come up with a Arduino-based device that allows access to Arduino shields, sensors etc. by means of accessing this device via the R: handler.
On the hardware side, I've already set things up (all you need is Data In, Out, Command and GND), and when the device is connected, I can see the typical command frame on the serial interface of the Arduino when the ATARI boots up.
What puzzles me, however, is that no other devices seem to send anything on the SIO bus if the device is not connected. For example, when I tell DOS to list the directory on a printer with
I only get the error on the ATARI, but no data shows up on the bus.
The same goes for accessing the R: handler with any of the drivers known to me which come with Itay's ICE-T disk image, as well as the ARGS drivers (https://atariwiki.or...RS232 Cartridge). For example, the PRCONN driver loads fine, and when accessing R: through a simple BASIC program, such as
OPEN #1,4,0,"R:":FOR X=1 TO 1000:GET #1, A:PRINT A:NEXT X
prints "1" repeatedly, but nothing comes up on the bus.
My plan B would be to implement access via one of the unused disk drive ids (such as D7: ), becaus that apparently seems to work. But having it based on R: would make it more convenient to use with other programs, such as terminals like ICE-T and others.
If anone has an idea how to move on from here, I'd be very grateful.