Make local echo in STM8 eForth optional

ECHO

\ STM8 eForth ECHO 
\ Make local echo in STM8 eForth optional
\ Note1: since this code patches TAP, and sets the startup word, 
\       it should be loaded with #require ECHO
\ Note2: the RAM address of variable TAPECHO must be below 0x0100,
\       it's recommended to #require ECHO early on in the main file
\ Note3: this file sets the 'BOOT vector for initializing TAPECHO -
\       any startup code must execute this task!

#require TAP
#require 'PROMPT
#require .OK
#require HI

  NVM 
  VARIABLE TAPECHO

  : ECHO ( f -- )
    \ turn on (true), or off (false) interpreter echo
    ( f ) IF 
      [ ' TX! ] LITERAL TAPECHO !
      [ ' .OK ] LITERAL 'PROMPT !
    ELSE
      [ ' DROP ] LITERAL TAPECHO !
      [ ' CR ] LITERAL 'PROMPT !
    THEN
  ;

  \ Initialize ECHO
  -1 ECHO
    
  \ patch TAP
  TAPECHO ' TAP 5 + C!

  : START ( -- )
    \ code for initializing TAPECHO
    0 ECHO
    \ HI
  ;

  \ set 'BOOT to startup code 
  ' START 'BOOT !
  RAM