tinystories-imac-g3

TinyStories 260K for a 1998 iMac G3

This repository packages source and conversion tools for running a tiny TinyStories language model locally on a stock 1998 iMac G3 with 32 MB of RAM, Mac OS 8.5, and a 233 MHz PowerPC 750 processor.

The original project ports a small llama2.c-style TinyStories model to Classic Mac OS. A prompt is written to prompt.txt; the app tokenizes it, runs local transformer inference, and writes the generated continuation to output.txt.

This prepared Hugging Face package does not include generated big-endian model files or a prebuilt Classic Mac app binary. It includes the runtime source, Retro68 build files, and conversion script needed to produce the Mac-ready artifacts from karpathy/tinyllamas.

Contents

• source/imac_llm.c: Classic Mac OS inference runtime.
• source/imac_llm.r: Mac resource file.
• source/CMakeLists.txt: Retro68 build configuration.
• source/imac-llm-repo.tar.gz: archived source snapshot from the GitHub repo.
• scripts/endian_swap.py: converts Little Endian model/tokenizer files for PowerPC.

Model Lineage

The runtime targets karpathy/tinyllamas TinyStories 260K:

• dim=64
• hidden_dim=172
• n_layers=5
• n_heads=8
• n_kv_heads=4
• vocab_size=512
• checkpoint size around 1 MB

The Classic Mac port fixes the grouped-query attention weight layout for this model shape and byte-swaps the model/tokenizer for the PowerPC 750's big-endian architecture.

Build

Download the upstream model artifacts:

curl -L -o stories260K.bin https://huggingface.co/karpathy/tinyllamas/resolve/main/stories260K/stories260K.bin
curl -L -o tok512.bin https://huggingface.co/karpathy/tinyllamas/resolve/main/stories260K/tok512.bin
python3 scripts/endian_swap.py

Then build the Classic Mac OS app with Retro68:

mkdir build
cd build
cmake ../source -DCMAKE_TOOLCHAIN_FILE=/path/to/Retro68-build/toolchain/powerpc-apple-macos/cmake/retroppc.toolchain.cmake
make

Expected generated outputs from the original project include a MacBinary app, disk image, and Classic Mac application bundle depending on the Retro68 build configuration.

Runtime Target

• iMac G3 Rev B, October 1998
• 233 MHz PowerPC 750
• 32 MB RAM
• Mac OS 8.5
• no command line required on the target machine

Limitations

• Requires Retro68 for building.
• Requires manual transfer to the iMac over FTP/HTTP or another Classic Mac-friendly path.
• Requires increasing the Classic Mac app memory partition.
• Uses a tiny model intended for children's-story continuations, not assistant behavior.
• Big-endian generated model files are not included in this prepared package.

Citation and Links

• GitHub: https://github.com/maddiedreese/imac-llm
• Base artifacts: https://huggingface.co/karpathy/tinyllamas/tree/main/stories260K
• TinyStories paper: https://arxiv.org/abs/2305.07759
• llama2.c: https://github.com/karpathy/llama2.c
• Retro68: https://github.com/autc04/Retro68