ASM sources are greatly polished. More explanations are added as
comments. Split environmental variable 'systemID' into 'CPU' and
'Model'. Most hForth source files can be used with other CPUs
without modification by using conditional compilation (see
COREEXT.F and DOUBLE.F for example). Thanks Neal Crook for comments
and many valuable suggestions. Now all ASM sources can be assembled
by TASM 1.0 and MASM 6.11. Many typographical errors are corrected.

Control structure words are all revised. Control-flow stack is
implemented on data stack. Control-flow stack item is represented by
two data stack items as below:

Control-flow stack item     Representation (parameter and type)
-----------------------    -------------------------------------
     dest                    control-flow destination      0
     orig                    control-flow origin           1
     of-sys                  OF origin                     2
     case-sys                x (any value)                 3
     do-sys                  ?DO origin           DO destination
     colon-sys               xt of current definition     -1

hForth can detect a nonsense clause such as "BEGIN IF AGAIN THEN"
easily. CS-ROLL and CS-PICK can be applied to the list of dests and
origs only. This can be verified by checking whether the ORed type
is 1. I can not think of a control-structure-mismatch that current
hForth cannot catch.

Some bugs are fixed including RESTORE-INPUT.


Changes from 0.9.9

1997. 6. 30.
      Add TRHOW after FLUSH-FILE in SAVE-BUFFERS and BYE in MSDOS.F.

1997. 6. 23.
      Fix pack" in HF86ROM.ASM and HF86RAM.ASM.
      Fix SIO.F according to new EXE program structure.

Changes from 0.9.7

1997. 5. 26.
      MSDOS.F: Fix RESTORE-INPUT to restore BLK correctly.
1997. 2. 28.
      Facelift to be used with other CPUs.
1997. 2. 19.
      Split environmental variable systemID into CPU and Model.
1997. 2. 6.
      Add Neal Crook's microdebugger and comments on assembly definitions.
1997. 1. 25.
      Add $THROWMSG macro and revise accordingly.
1997. 1. 18.
      Remove 'NullString' from assembly source.
1996. 12. 18.
      Revise 'head,'.
1996. 12. 14.
      DOSEXEC.F: Revise (DOSEXEC) in MSDOS.F.
1996. 12. 6.
      OPTIONAL.F: Fix 'compiles>' for colon-sys.
1996. 11. 29.
      OPTIONAL.F: Remove PICK which was added in assembly source.
      OPTIONAL.F: Revise CASE, ENDCASE, OF, ENDOF, RETRY for
		control-flow stack.
      OPTIONAL.F: Revise '.xt' due to the removal of 'do."' and change
		of 'doS"'.
1996. 12. 3.
      Revise PICK to catch stack underflow.
1996. 11. 29.
      Implement control-flow stack on data stack. Control-flow stack
	      item consists of two data stack items, one for value
	      and one for the type of control-flow stack item.
      control-flow stack item	data stack representation
	      dest	      control-flow_destination	      0
	      orig	      control-flow_origin	      1
	      of-sys	      OF_origin 		      2
	      case-sys	      x (any value)		      3
	      do-sys	      ?DO_origin	 DO_destination
	      colon-sys       xt_of_current_definition	     -1
      Add PICK.
      'bal' is now the depth of control-flow stack.
      Drop 'lastXT'.
      Introduce 'notNONAME?'
      Add 'bal+' and 'bal-'. Drop  'orig+', 'orig-', 'dest+', 'dest-',
	      'dosys+', and 'dosys-'.
      Revise ':NONAME', ':', ';', 'linkLast', 'head,', RECURSE, 'DOES>',
	      CONSTANT, CREATE, VALUE, VARIABLE, and QUIT.
	      This change makes RECURSE work properly in ':NONAME ... ;'
	      and '... DOES> ... ;'.
      Revise 'rake', AGAIN, AHEAD, IF, THEN, +LOOP, BEGIN, DO, ELSE, LOOP,
	      UNTIL, and WHILE.
      Revise SLITERAL, '."', 'doS"' to allow a string larger than
	      max char size.
      Revise $INSTR and remove 'do."'.
      Revise 'pack"'.
      ASM8086.F: Revise ';CODE' for control-flow stack.
      COREEXT.F: Provide CODE definition of ROLL.
      COREEXT.F: Revise '?DO' for control-flow stack.
      COREEXT.F: Revise 'C"' to catch exception -24 'parsed string overflow'.
1996. 8. 17.
      HF86EXE.ASM: Revise MAX-UD.
1996. 8. 10.
      HF86EXE.ASM: Replace 'COMPILE,' with 'code,' in the definition of
		'compileCREATE'.
1996. 7. 19.
      DOUBLE.F: Fix 'M+'. Thanks M. Edward Borasky.
1996. 6. 19.
      Fix '/STRING'.
1996. 4. 15.
      ASM8086.F: ';CODE' is fixed. END-CODE is changed.
1996. 3. 1.
      MSDOS.F: Shift value of 'ior' of FILE words to system THROW code area,
		i.e. -4096..-256 .
      MSDOS.F: Remove subtle bug in 'SAVE-SYSTEM-AS'.

Changes from 0.9.6

1996. 2. 10.
      Revise FM/MOD and SM/REM to catch result-out-of-range error in
	      '80000. 2 FM/MOD'.
1996. 1. 19.
      Rename 'x,' to 'code,'; 'x@' to 'code@'; 'x!' to 'code!';
	      'xb@' to 'codeB@' and 'xb!' to 'codeB!'.
1996. 1. 7
      Rename non-Standard 'parse-word' to PARSE-WORD.
1995. 12. 2
      Drop '?doLIST' and revise 'optiCOMPILE,'.
1995. 11. 28
      Drop 'LIT,:' all together.
      Return CELLS to non-IMMEDIATE definition.

Changes from 0.9.5

1995. 11. 27.
    In ASM8086.F
    ';CODE' is redefined following the change of 'DOES>' and 'doCREATE'.
1995. 11. 25.
    Add RETRY described by Dr. Astle in Forth Dimensions 17(4), 19-21 (1995).
1995. 11. 25.
    Make 'lastXT' VALUE word.
1995. 11. 24.
    For RAM model only
	Replace 'xhere' with HERE.
	Revise doVALUE, VALUE, TO, and all $VALUE macros.
1995. 11. 23.
    Revise doCREATE, CREATE, pipe, DOES>, and >BODY.
    'pipe' is no longer processor-dependent.
1995. 11. 17.
    Move ERASE to ASM8086.F.