----- Original Message ----- From: "Mark McDougall" <msmcdoug at optushome.com.au> > I'm not sure how the CoCo drive works - I'm guessing from your comments it > doesn't interrupt the 6809 when data is ready?!? IIRC the drive HALTs the processor until the buffer is transferred. That's why the OS-9 clock gets off time when you do disk I/O. NM