Function 0Ch (peek) never worked correctly (character was not returned in AX); I guess nothing uses this function (?).

Function 01h (transmit char w/wait) now will set the timeout flag (0x8000) in the AX if the VDD_WRITE function fails (returns value other than 1).

Optimize Function 18h (read block) - no need for the extra VDD_STATUS call.

Use newly defined FOSSIL macros instead of magic numbers of port status bits.

Log the git branch/hash values to the Windows debug log (via sbbsexec.dll).