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COR24 BASIC — Demo Programs

A small gallery of programs that exercise the v1 interpreter. Each demo has a matching scripts/demo-<name>.sh wrapper that builds (if needed) and runs the corresponding examples/<name>.bas through pv24t, the host-side p-code interpreter.

Running

./scripts/build-basic.sh        # one-time, or after editing src/
./scripts/demo-hello.sh
./scripts/demo-calc.sh
./scripts/demo-fizzbuzz.sh
./scripts/demo-fibonacci.sh
./scripts/demo-factorial.sh
./scripts/demo-count.sh
./scripts/demo-memdump.sh
./scripts/demo-startrek.sh
./scripts/demo-trek-adventure.sh
./scripts/demo-robot-chase.sh

Each script feeds the .bas file to the interpreter as if it were typed at the REPL. The files include trailing RUN and BYE lines so they run end-to-end and exit cleanly.

Demo Index

Script File What it shows
demo-hello.sh examples/hello.bas Immediate-mode PRINT and BYE. The smallest possible program.
demo-calc.sh examples/calc.bas Arithmetic, LET, mixed string/expression PRINT. (Note: shows the open ABS bug — see issue #1.)
demo-fizzbuzz.sh examples/fizzbuzz.bas FOR/NEXT, IF...THEN GOTO, divisibility via (I/N)*N=I, multi-target dispatch.
demo-fibonacci.sh examples/fibonacci.bas Iterative two-variable swap inside FOR/NEXT. First 10 Fibonacci numbers.
demo-factorial.sh examples/factorial.bas Iterative product accumulator inside FOR/NEXT. Mixed-type PRINT of N;"!=";F.
demo-count.sh examples/count.bas Minimal FOR/NEXT smoke test, counts 1..10.
demo-memdump.sh examples/memdump.bas POKE then PEEK round-trip on a low scratch address. Demonstrates the byte-MMIO syntax.
demo-startrek.sh examples/startrek.bas Full Star Trek battle game — 8×8 galaxy, phasers, torpedoes, shields, warp/impulse movement. Biggest program in the suite.
demo-trek-adventure.sh examples/trek-adventure.bas Text adventure translated from a 1980s magazine BASIC listing. Wake alone on a doomed Enterprise, find tools, patch the engine before orbit decays. Numeric menu parser (no string variables in v1).
demo-robot-chase.sh examples/robot-chase.bas 9×9 text-grid port of the 1970s Chase / Robots game. Keypad movement (1–9, 5=wait), teleport (0), and a 3×3 LRS-style regional summary (10=LRS). Exercises PEEK/POKE to emulate parallel arrays for robot state.
(no wrapper) examples/blink.bas LED blink loop targeting the COR24 LED MMIO at 0xFF0000. Hardware/cor24-emu only — pv24t traps because the address is outside its VM memory.

Demo Notes

hello.bas

PRINT "HELLO WORLD"
BYE

Immediate mode — no line numbers. The simplest possible smoke test.

calc.bas

Demonstrates arithmetic precedence ((A+B)*2), integer division (100/7=14), and the mixed-type PRINT form (PRINT "X=";X).

Open bug: the last line shows ABS(-42)=10 instead of 42. ABS is declared in src/basic_tokens.pas but not initialized in the ik keyword table, so the tokenizer falls through and consumes A as variable A. Tracked in sw-cor24-basic#1 and queued as saga step 025-fix-abs-bug.

fizzbuzz.bas

There is no MOD operator in v1. Divisibility is tested with (I/N)*N = I since integer division truncates. The dispatch chain checks 15 first, then 3, then 5; each branch jumps to a print line and back to NEXT via GOTO.

fibonacci.bas

Classic three-variable rotation:

50 PRINT A
60 LET C=A+B
70 LET A=B
80 LET B=C

Outputs the first ten terms (0..34). Watch out for overflow: integers are 24-bit signed, so the sequence stays valid up through the low millions.

factorial.bas

N! via straight FOR I=1 TO N accumulation. With N=7 you get 5040. The 24-bit integer ceiling caps you at 12! (479,001,600); 13! overflows.

count.bas

The smallest stored-program example: FOR I=1 TO 10 / PRINT I / NEXT. Useful as a baseline when poking at the build pipeline.

memdump.bas

Pokes the bytes 72, 73, 33 ('H', 'I', '!') into addresses 100..102, then loops with PEEK(I) to print each byte:

100=72
101=73
102=33

The address range is just regular pv24t VM memory; no MMIO. The demo exists to show that the language form POKE addr,val and PEEK(addr) round-trips correctly. For real MMIO targets, see blink.bas.

blink.bas — hardware only

POKE 16711680,0 then POKE 16711680,1 toggles bit 0 at COR24's IO_LEDSWDAT register (0xFF0000), where LED D2 lives. On real hardware (or cor24-emu) this physically blinks the LED.

Under pv24t it traps. The host-side p-code interpreter only allocates linear VM memory and 0xFF0000 is far outside the allocated region. There is intentionally no demo-blink.sh wrapper — running it would just trap. To exercise it, target the emulator/hardware p-code VM (pvm.s) instead of pv24t. That path isn't wired into build-basic.sh yet; it'll come with the unit build pipeline (steps 018–019) which produces a .p24m image loadable by cor24-emu.

Same caveat applies to LED/switch-style demos in general: under pv24t the LED syscall (sys 3) is a no-op and READ_SWITCH (sys 6) always returns 0.

Recursion?

Short answer: no, not usefully.

COR24 BASIC v1 has GOSUB/RETURN with a 64-deep return stack, so you can call a subroutine from within itself — the return addresses nest correctly. But there are no parameters and no per-call locals: all 26 variables (A..Z) are global. Each "recursive" call overwrites the same storage as its caller, so by the time RETURN fires, the supposed "local state" is gone.

There is also no tail-call optimization. GOSUB always pushes, RETURN always pops; a GOSUB immediately followed by RETURN still consumes a stack slot for the duration of the call. Every level counts against the 64-slot ceiling.

The practical implication: write loops, not recursion. Factorial, Fibonacci, GCD, and friends are all comfortable as iterative FOR/NEXT or GOTO loops, which is exactly the style this flavor of BASIC was designed for.

Adding a new demo

  1. Drop examples/<name>.bas ending with RUN and BYE.
  2. Copy an existing wrapper: 
    cp scripts/demo-hello.sh scripts/demo-<name>.sh
sed -i '' "s/hello/<name>/g" scripts/demo-<name>.sh
  3. Add a row to the table above.
  4. ./scripts/demo-<name>.sh to verify.