avrbasic

An interactive BASIC interpreter for the ATmega328p.

Re-live your TRS-80 memories with your ATmega. Maybe.

I’ll do a hardware diagram and stuff like that soon.

Parts list:

• ATmega328p
• ST7920, headers, lots of pin–plug header cables
• the keyboard in /keyboard, or anything else that uses UART
• Whatever you use to program and power your AVR

Language description:

• Integers and strings are supported.
  • Integers are any string of numbers from -32768 to 32767.
  • Strings are any set of characters within double-quotes. No escaping is permitted.
• Variables are identified by labels ending in % (integers) or $ (strings).
  • Only the first two letters are significant.
  • XY% and XYZ% are the same (integer) variable.
  • XY$ is a (distinct) string variable.
• Expressions are numbers, strings, labels (variable references), in conjunction with any combination of +, -, *, /, = (equality test).
  • Usual binding order applies. Override with parentheses.
  • Numbers support all operators. Strings only support + and =.
  • Testing equality results in the number 1 (true) or 0 (false) regardless of the operand types.
• The following statements are supported:
  • LET label = expr — assign a variable
  • PRINT expr[, expr …] — output any expression
  • INPUT ["MESSAGE",] label — get user input
  • IF expr THEN — start executing code only if expr is a non-zero integer or non-empty string
  • ELSEIF expr THEN — during an IF, if a previous block has not executed, start executing code if expr evaluates as above
  • ELSE — during an IF/ELSEIF, if no previous block has executed, start executing code
  • END IF — end an IF/ELSEIF
  • [number] stmt — store program code at the given line number
  • GOTO number — transfer program control to given line during RUN
  • RUN — run stored program
  • LIST — list stored program code
  • CLEAR – erase stored program (use if pheap runs out)