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I can get Multi-User BASIC to run with the two serial ports at 020 and 022 (octal) but when I change BASIC's setup to include the third serial port at 006 octal (the SIO board running the cassette interface, adjusted to 9600 baud and 8N1) I find that Multi-User BASIC isn't running on that third terminal. BASIC still fires up, it just isn't talking to the third terminal (which terminal works fine when plugged into port 020). Anyone know what I'm missing?

Regards

Gabriel Egan

Timesharing BASIC requires all terminals to be on a 2SIO (or equivalent) port. Set port 3 to be a 2SIO port instead of SIO and it will work.

Mike

Great! That worked. Three dumb terminals running BASIC at once off of processor makes the modern computers in my lab looked puny, even if BASIC is a little slow. Incidentally, there's a 'gotcha' in the Serial Port Setup using octal (so the ports are 020, 022, 024) and BASIC using decimal (so the same ports are 16, 18, 20), but that's just the sort of thing my students need to be aware of so it's all good.

I did notice also that Multi-User BASIC is set up by default to put ports 16 and 18 at interrupt level 2 and put port 20 at interrupt level 3. My first instinct was to change the setup so that all three ports are at interrupt level 2 but although Multi-User BASIC allows this configuration it won't boot with those settings. I'm guessing that the 88-VI board only allows two devices at each interrupt level, although I'm still only part-way through understanding the manual for that device.

What a marvellous learning experience this all is. Kudos to the clone manufacturer.

Gabriel Egan