figForth Glossary

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Glossary: “an alphabetical list, with meanings, of the words or phrases in a text that are difficult to understand…“ Cambridge Dictionary

Important Forth Concepts/Definitions…

  • The Dictionary

Linked List

  • The Dictionary’s Linked List Structure

Dictionary/Word Fields

  •   Name Field
  •   Link Field
  •   Code Field
  •   Parameter Field

Stack Requirements

  • Stack Requirements

Forth Words

Glossary Item Format

The first line of each entry shows a symbolic description of the action of the procedure on the parameter stack. The symbols indicate the order in which input parameters have been placed on the stack. Three dashes “—” indicate the execution point; any parameters left on the stack are listed. In this notation, the top of the stack is to the right The definitions are presented in the order of their ASCII sort

All symbols are 16-bit values on the Parameter Stack ("the stack")

            The symbols include:
addr    memory address
b       8 bit byte (i.e. high 8 bits zero) within a 16-bit word
c       7 bit ASCII character (high 9 bits zero)  within a 16-bit word
d       32 bit signed double integer, most significant portion with sign on top of the stack
ud      32 bit unsigned double integer, most significant portion on top of the stack
f       boolean flag. 0 = false, non-zero = true
ff      boolean false flag = 0
tf      boolean true flag = non-zero
n       16 bit signed integer number
u       16 bit unsigned integer

    The capital letters on the right show definition characteristics:
C   May only be used within a colon definition. A digit indicates number of memory addresses used,
                                                    if greater than one
E   Intended for execution only
P   Has precedence bit set. Will execute even when compiling
U   A User variable

Unless otherwise noted, all references to numbers are for 16 bit signed integers. on 8 bit data bus computers, the high byte of a number is on top of the stack, with the sign in the leftmost bit. For 32 bit signed double numbers, the most significant part (with the sign) is on top
All arithmetic is implicitly 16 bit signed integer math, with error and underflow indication unspecified

Word Requirements

“the words or phrases in a text that are difficult to understand”, or rather, in this case, to define a set of rules (“requirements”) that determine the behaviour of Forth Words…

Stack Requirements

As Forth uses the Parameter Stack to pass values during the execution of Forth Words, there are some simple stack rules (“requirements”) to be followed for each Word and these stack rules are documented

Alphabetically

!    !CSP    <#    #    #>    #S    ‘    (    (.”)    (+LOOP)    (;CODE)    (DO)    (FIND)    (LOOP)    (NUMBER)    *    */    */MOD    +    +!    +-    +LOOP    ,    -    -DUP    -FIND    -TRAILING    .    .”    .R    /    /MOD    0    0<    0=    0>    0BRANCH    1    1+    1-    2    2!    2*    2+    2-    2@    2DROP    2DUP    2SWAP    :    ;    ;CODE    ;S    <    <BUILDS    =    >    >R    ?    ?COMP    ?CSP    ?DUP    ?EXEC    ?PAIRS    ?STACK    ?TERMINAL    @ ABORT    ABS    AGAIN    ALLOT    AND    BACK    BASE    BEGIN    BL    BINARY    BLANKS    BRANCH    C!    C,    C@    CFA    CMOVE    COLD    COMPILE    CONSTANT    CONTEXT    COUNT    CR    CREATE    CURRENT    CSP    CONTEXT    D!    D+    D-    D.    D.R    D0=    D<    D=    D>    D@    DABS    DECIMAL    DEFINITIONS    DEPTH    DIGIT    DLITERAL    DMINUS    DO    DOES>    DP    DPL    DROP    DUP    ELSE    EMIT    ENCLOSE    END    ERASE    ERROR    EXECUTE    EXPECT    FENCE    FILL    FLD    FORGET    FORTH    HERE    HEX    HLD    HOLD    I    ID.    IF    IMMEDIATE    IN    INTERPRET    J    KEY    LATEST    LEAVE    LFA    LIT    LITERAL    LOOP    M*    M*/    M/    M/MOD    MAX    MIN    MINUS    MOD    NFA    NOOP    NUMBER    OR    OUT    OVER    P!    P@    PAD    PFA    QUERY    QUIT    R0    R>    R@    REPEAT    ROT    RP!    RP@    S->D    S0    SIGN    SMUDGE    SP!    SP@    SPACE    SPACES    STATE    SWAP    THEN    TIB    TOGGLE    TRAVERSE    TYPE    U*    U.    U.R    U/    U<    UNTIL    USER    VARIABLE    VLIST    VOCABULARY    VTABLE    WARM    WARNING    WHILE    WORD    XOR    [    [COMPILE]    ]

Primatives (“Code Definitions”)

FILL    ROT    <    -    2-    2+    1+    1-    P!    D!    C!    !    P@    D@    C@    @    TOGGLE    +!    2DUP    DUP    2SWAP    SWAP    2DROP    DROP    OVER    DMINUS    MINUS    D+    +    0<    0=    >R    R>    R@    LEAVE    ;S    RP@    RP!   S->D    SP!    SP@    AND    OR    XOR    U/    U*    CMOVE    ?TERMINAL    EMIT    KEY    ENCLOSE    (FIND)    DIGIT    J    I    (DO)    (+LOOP)    (LOOP)    0BRANCH    BRANCH    EXECUTE    LIT   

“Compile-Time” Words

COLON    CONSTANT    DOES>    USER    VARIABLE    VOCABULARY    .”    ;CODE    AGAIN    ELSE    REPEAT    IF    LITERAL    LOOP    +LOOP    THEN    UNTIL    WHILE   

“Run-Time” Words

DOCOL    DOCON    DODOES    DOUSE    DOVAR    DOVOC    ;S    LIT    (;CODE)    BRANCH    0BRANCH    (LOOP)    (+LOOP)    (.”)   

Entry Points

NEXT    WHPUSH    HPUSH    PAUSE

Other Meanings

The “input stream”

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