This ROMWBW version is an extract of https://github.com/mecparts/zmp/bin
as at Aug 23rd, 2021.

- Overlay files must reside on default drive at time program is
  launched.  This seems to preclude the path search feature of
  ZSDOS/ZCPR which would be nice.  Need to look into this.
- Need some mechanism for user to select a CIO unit other than CIO 1
  without modifying and rebuilding application.
- Initialization messages refer to CIO 1 as CIO 0
- System hangs after error message if there is no CIO 1 unit
- When leaving program, terminal cursor remains hidden

--WBW 1:42 PM 8/23/2021

- When leaving program, terminal cursor remains hidden (fixed)
- System hangs after error message if there is no CIO 1 unit (fixed)
- Initialization messages refer to CIO 1 as CIO 0 (fixed)

--WBW 1:58 PM 8/23/2021

- Restore cursor on normal program exit.
- Revert original HBIOS conout and default console code as there
  is no associated facility for direct HBIOS conin.
- Allow setting port 0 and port 1 CIO device from command line
  ZMP 2 sets comms port to CIO 2. Can set primary and secondary
  i.e. ZMP 21 but only primary supported on this ZMP version.
  Untested on Ron Murrays ZMP15
- Space getting short so messages shortened. 

--PMS 8/24/2021

- Refactored overlay to resolve some stack issues.
- Removed support for setport because it didn't make much sense
  with ability to specify port on command line.
- Added an equate (pcfg) which controls whether port configuration
  is implemented.  It is set to false (no port configuration).
  because ZMP it is unable to handle   many RomWBW serial port settings 
  (notably the hard-wired 115200 baud of many RCBus systems).  You 
  must now used MODE to configure port before starting ZMP.

--WBW 1:55 PM 4/16/2025