I have a report from the owner of the all three devices that they do not work when all are being employed.
When GR8NET and MFR are inserted into the machine, machine behaves weirdly restarting and rebooting, but sometimes works properly after several reboots. I am trying to find the cause of it, to no much success so far.
I need people who have all three devices to build this configuration and see if it works properly - will be clear if machine will start and get through to game in MFR or to BASIC several times.
Technical info: for some reason machine misbehaves when GR8NET is searching for its other instances through the machine; I looked into circuit diagram, and see that WSX has series resistors on the signal wires towards the slots. Not sure what designers wanted to achieve, but as MFR, most probably, does not have logic shifter and uses series resistors to divide input voltage to 3.3V specification, it will consume some current in any state, causing voltage drop because of resistors on the machine's main board. This may also cause signal distortions. This is anecdotic theory, but I can not come out with any other which would explain the nature of failure.
