PIA question

[bxdanny]

When an OSI dual-drive system is booted, Port A of the disk PIA is initially configured by the boot ROM as all inputs, even though line PA6 is really an output, the drive B select line. That doesn't seem to cause any problems; the system boots fine from the A drive, and the B drive doesn't interfere. So I'm guessing that means that the line is physically in a high (logic 1) state, keeping the B drive deselected.

Now suppose software tries to set the line low, but without changing the data direction register. Will it in fact go low, or will it remain high (perhaps with a read of the port nevertheless indicating that it is low)? Will doing this put undue strain on the chip?

I have realized that my "Enhanced Pico-Dos" is in fact doing this if you try to SElect drive B. The current version will configure the PIA correctly if it is reset and warm-started, but otherwise it won't. Drive B access works fine in the emulator, but I am thinking that perhaps it will not on real hardware.