CLRCHN insights.

[Whammo]

CLRCHN does two things:

1. Sets screen and keyboard as the current output and input channels respectively.

2. Sends IEC UNLISTEN and/or UNTALK over the serial bus if- there were current IEC channels.

Use CLRCHN after:

-OPEN-ing other I/O channels (like a tape or disk drive)

Use CLRCHN before:

• CLOSE-ing a current channel.

• CHKIN: When changing the current input channel from keyboard to any OPEN-ed input channel.

• CHKOUT: When changing the current output channel from screen to any OPEN-ed output channel.

[Whammo]

CLRCHN does not seem to be needed after opening channel #15, the command channel. #389
Even after having opened the buffer file- s" #" 2 2 open ioabort
Absolutely required when opening #8 to load the directory. #550

[Whammo]

I think the takeaway is that files are a bit wonky but quite friendly in BASIC. Redirecting input from the disk and the screen(?) is also the foundation of durexForth.