web-sw-cor24-smalltalk

Browser-based live demo for the sw-cor24-smalltalk project: a tiny integer-only "Tinytalk" hosted entirely in COR24 BASIC v1, in the spirit of the ~1000-line BASIC-hosted Smalltalk evaluator that Alan Kay's group built in 1972.

Live demo: https://sw-embed.github.io/web-sw-cor24-smalltalk/

Part of the Software Wrighter COR24 Tools Project.

Intro

Three nested fetch/decode/execute loops are running at all times in your browser:

Browser (WASM):
  pa24r p-code VM        <- runs the BASIC interpreter
  +- COR24 BASIC v1      <- runs vm.bas + image_dN.bas + dN_*.bas
     +- Tinytalk VM      <- src/vm.bas: dispatch, send, primitives
        +- Smalltalk image  <- class table, method dicts, bytecodes

Same architecture as the rest of the web-sw-cor24-* family (basic, pascal, snobol4, forth, ...): one Yew SPA, one Trunk build, one p-code VM in WebAssembly. No backend.

The point is not speed (it is slow). The point is to make the mental model of object-oriented dispatch visible: every step the VM takes runs through real CLASSOF -> LOOKUP -> ACTIVATE -> primitive-or-frame-push, hand-coded as GOSUB chains in BASIC.

Quickstart

# Run the dev server (port 9075, exclusive dist/ lock).
./scripts/serve.sh

# Open http://localhost:9075/

Pick a demo from the dropdown and hit Run (or Cmd/Ctrl-Enter). Esc stops a running session. Reset reloads the demo source. Clear wipes the output panel. For the interactive demo (d5_calc), an input row appears below the output -- type a value and press Enter (or click Send).

Demos

Seven demos ship with the build, bundled at compile time from ../sw-cor24-smalltalk/{src,examples}/ via build.rs:

Demo	Result	Description
repl	varies	Interactive integer calc REPL (default). Selectors: 1=+ 2=- 3=* 4=< 14=max:; 0 quits.
hello	hello, world	Smallest possible v1-dialect demo: Transcript show: 'hello, world'. Transcript cr. First demo to print real text instead of bare integers.
add	7	3 + 4 via SmallInteger>>+ (primitive method).
counter	2	Counter class with one instance variable; user-defined init / incr / value; nested user->primitive sends.
boolean	42	5 < 10 ifTrue: 42 ifFalse: 0 via True/False objects with their own polymorphic ifTrue:ifFalse:. No native IF makes the choice.
max	5	5 max: 3 via SmallInteger>>max: whose bytecode uses JUMP_IF_FALSE for real conditional control flow inside a Smalltalk method.
factorial	120	5 fact via recursive SmallInteger>>fact. First proof that the v0 frame stack handles non-trivial nesting.
bounded	5	BoundedCounter extends Counter, overriding incr to cap at 5; init and value resolve via the superclass walk. First inheritance demo.

The source pane shows the canonical Smalltalk source (.st) for each demo. Under the hood, build.rs runs tools/stc.awk (the COR24 Smalltalk compiler in ../sw-cor24-smalltalk/) to produce the per-demo image, which is concatenated with vm.bas and the hand-assembled top-level driver into the BASIC bundle the WASM runner executes. BASIC is implementation substrate, not surfaced in the UI.

Architecture

• assets/basic.p24 -- the COR24 BASIC v1 interpreter, compiled Pascal-to-p-code, vendored via scripts/vendor-artifacts.sh from ../sw-cor24-basic/build/ (or ../web-sw-cor24-basic/assets/ as fallback).
• build.rs -- for each demo, runs tools/stc.awk from the source repo to compile examples/<demo>.st to its image, then concatenates image + vm.bas + examples/<demo>.bas (the hand-assembled top-level driver), stripping trailing RUN/BYE so runner.rs can append the right ones based on the demo's interactive flag. Also embeds basic.p24 and emits BUILD_SHA / BUILD_HOST / BUILD_TIMESTAMP for the footer.
• src/runner.rs -- ports pv24t (the canonical p-code tracer) to Rust/WASM. Loads basic.p24 into memory, feeds the BASIC bundle into the interpreter as stdin, ticks in 200 K-instruction batches, pauses at INPUT for interactive demos.
• src/lib.rs -- Yew App: demo dropdown, read-only Smalltalk source pane, output pane, status bar with a budget escalator, REPL input row, octocat corner, footer with build stamp.
• src/demos.rs -- static catalog. smalltalk field is include_str! from ../sw-cor24-smalltalk/examples/<demo>.st; runtime field is include_str! from OUT_DIR (the compiled BASIC bundle).
• scripts/serve.sh -- dev server on port 9075 with an exclusive dist/ lock (prevents races between a running server and a stray trunk build).
• scripts/build-pages.sh -- release build into pages/ for GitHub Pages, same lock.

Build for GitHub Pages

./scripts/build-pages.sh
git add pages/
git commit -m "Release: deploy <date>"
git push

The --public-url is /web-sw-cor24-smalltalk/ so paths resolve under https://sw-embed.github.io/web-sw-cor24-smalltalk/.

Related projects

• sw-cor24-smalltalk -- the Tinytalk VM and per-demo images this site runs.
• sw-cor24-basic -- the COR24 BASIC v1 interpreter source (Pascal -> p-code).
• sw-cor24-pcode -- canonical p-code VM, assembler (pa24r), tracer (pv24t).
• web-sw-cor24-basic, web-sw-cor24-pascal, web-sw-cor24-ocaml, web-sw-cor24-snobol4 -- sibling browser demos in the same family.

Links

• Blog: Software Wrighter Lab
• Discord: Join the community
• YouTube: Software Wrighter

Copyright

Copyright (c) 2026 Michael A. Wright

License

MIT. (C) 2026 Michael A Wright. See LICENSE.