This is a fork of ubasic with the aims of

• Making it smaller (removing lots of the more memory expensive coding)
• Bringing it up to ECMA55 and a bit beyond
• Making it faster (pretokenisation etc)
• Making it run on FUZIX boxen usefully

Currently

• Negative numbers are now supported
• Types for things are a bit clearer as they will matter
• Upper or lower case is permitted
• Errors in the original debugging code are fixed
• Variables may now be A-Z or A0-A9..Z0-Z9 as per ECMA55
• PRINT supports , for tab fields, ; for supressing newline
• PRINT constant string length is unlimited
• INPUT is added including support for a prompt
• FOR NEXT now supports STEP as per ECMA55
• PEEK() is now a function as in normal basic - X = PEEK(4)
• STOP replaces the rather odd "END"
• ABS() INT() and SGN() are implemented
• REM works as in normal BASIC
• DATA and RESTORE are supported but not yet READ !
• AND and OR keywords work (but not yet NOT)
• GOTO and GOSUB allow expressions ("computed GOTO")
• GO SUB and GO TO are two tokens so can be spaced
• PRINT TAB() (SPC() is not ECMA55 nor is PRINT AT)
• String variables (A$-Z$ required)
• LEFT$(), RIGHT$(), MID$(), CHR$()
• VAL(),CODE()
• LEN()
• Proper print parsing (we don't allow PRINT ABC printing A then B then C. You must as in normal basic use ; or , .
• Faster RETURN and loops - we save the tokenizer pointer rather than mucking about playing hunt the line number
• Statements can be separated by :
• Removed the existing IF THEN ELSE in favour of a traditional IF THEN and : usage (IF THEN IF THEN ELSE ELSE ... gets horrible to parse and the old code messed it up badly)
• Arrays (1 or 2 dimensions required by ECMA55)
• Stdio is not used
• Logical expressions with AND and OR differently priorities to boolean & |
• Introduce "mod" to replace use of % - which we may need for other stuff later
• CLS
• PRINT AT

In comparison with ECMA55, then apart from all the floaty stuff it's missing

• Implicit dimensioning of arrays
• The ^ operator (or ** equivalent)
• RND
• SQR
• DEF FN / FN (single or no variable required by ECMA55)
• READ
• Unquoted data strings

Space saving work needed

• Replace malloc() with a proper sbrk based basic allocator
• Only prealloc A-Z/A$-Z$ pointers
• Work out why factor and relation are so big - and shrink them
• Why are input_statement and dim_statement so big ?
• Maybe kill the line finding array
• Fast way to walk lines
• Pretokenize code to make smaller and faster
• Switch to compiling ?

Other useful stuff to add

• XOR
• USR()
• INKEY$
• ON expr GO TO/SUB ... {ELSE}
• ON ERROR
• ON TIMER/SIGNAL
• PAUSE
• Short tokens "P." etc
• DO WHILE
• DO UNTIL
• I/O streams PRINT# INPUT# OPEN# CLOSE# etc
• Command mode
• CLEAR
• NEW
• SAVE / LOAD / CHAIN
• Unix syscall bindings 8)
• Unify GOSUB/NEXT/etc stack so that RETURN wipes out next frames etc