---
license: apache-2.0
library_name: gguf
pipeline_tag: text-generation
tags:
- ternary
- 1.58-bit
- gguf
- llama-cpp
- q2_0
- on-device
- prismml
- bonsai
base_model:
- prism-ml/Ternary-Bonsai-1.7B-unpacked
---
Prism ML Website |
White Paper |
Demo & Examples |
Discord
# Ternary-Bonsai-1.7B-gguf
Ternary (1.58-bit) language model in GGUF Q2_0 format for `llama.cpp`
## Resources
- **[White Paper](https://github.com/PrismML-Eng/Bonsai-demo/blob/main/ternary-bonsai-8b-whitepaper.pdf)**
- **[Demo repo](https://github.com/PrismML-Eng/Bonsai-demo)** — examples for serving, benchmarking, and integrating Bonsai
- **[Discord](https://discord.gg/prismml)** — community support and updates
- **Kernels**: Q2_0 is not yet in mainline `llama.cpp`. Use our fork at [PrismML-Eng/llama.cpp](https://github.com/PrismML-Eng/llama.cpp) (`prism` branch, default) which adds Q2_0 support for CPU (NEON/generic) and Metal. Upstream PR coming soon.
## Model Overview
| Item | Specification |
| :--------------- | :----------------------------------------------------------------------- |
| Base model | Qwen3-1.7B |
| Parameters | 1.72B |
| Architecture | GQA, SwiGLU MLP, RoPE, RMSNorm |
| Context length | 32,768 tokens |
| Vocab size | 151,936 |
| Weight format | GGUF Q2_0 g128: {-1, 0, +1} with FP16 group-wise scaling |
| Packed Q2_0 size | **436 MiB** (0.46 GB) |
| Ternary coverage | Embeddings, attention projections, MLP projections, LM head |
| License | Apache 2.0 |
## Quantization Format: GGUF Q2_0 (g128)
Each weight takes a value from {-1, 0, +1}, with one shared FP16 scale per group of 128 weights:
```
w_i = scale_g * t_i, t_i in {-1, 0, +1}
```
Q2_0 encodes each weight as a 2-bit code `q in {0, 1, 2, 3}`, dequantized via `w = (q - 1) * scale`. One 128-element block is 34 bytes (2 bytes FP16 scale + 32 bytes of packed 2-bit codes) for an effective **2.125 bits/weight**. The fourth code point (`q = 3`, reconstructing to `+2 * scale`) is reserved for future extensions; for ternary weights it is unused.
### Memory
| Format | Size | Reduction | Ratio |
| :---------------- | ----------: | --------: | ---------: |
| FP16 | 3.44 GB | -- | 1.0x |
| **GGUF Q2_0 g128**| **436 MiB** (0.46 GB) | **86.6%** | **7.5x** |
## Files in this repo
| File | Format | Size | Recommended |
| :-------------------------------- | :----- | -----: | :---------- |
| `Ternary-Bonsai-1.7B-F16.gguf` | FP16 | 3.44 GB | baseline / re-quantization source |
| `Ternary-Bonsai-1.7B-Q2_0.gguf` | Q2_0 (g128) | 442 MB | **recommended** (lossless for ternary) |
## Quickstart
### Build from the Prism fork
```bash
git clone https://github.com/PrismML-Eng/llama.cpp
cd llama.cpp
cmake -B build -DGGML_METAL=ON # or -DGGML_CUDA=ON, -DGGML_VULKAN=ON
cmake --build build -j
```
### `llama.cpp` CLI
```bash
./build/bin/llama-cli \
-m Ternary-Bonsai-1.7B-Q2_0.gguf \
-p "Explain quantum computing in simple terms." \
-n 256
```
### `llama.cpp` server
```bash
./build/bin/llama-server -m Ternary-Bonsai-1.7B-Q2_0.gguf -c 4096
```
## Throughput (llama.cpp, Apple M4 Pro 48 GB)
| Backend | PP512 (tok/s) | TG128 (tok/s) | FP16 TG (tok/s) | Speedup |
| :--------------- | ------------: | ------------: | ---------------: | ---------: |
| Metal (GPU) | 2,088 | **229** | 60 | **3.8x** |
| NEON CPU (10 t) | 508 | **123** | — | — |
Flags: `-ngl 99 -fa 1` for Metal; `-ngl 0 -fa 1 -t 10` for CPU.
## Fidelity (Q2_0 vs FP16 baseline)
Measured on wikitext-2 (20 chunks, context 512) via `llama-perplexity --kl-divergence`:
| Metric | Value |
| :------------------ | ---------: |
| Mean KL | 0.000000 |
| Top-1 agreement | 100.000 % |
| RMS Δp | 0.015 % |
| PPL ratio (Q/base) | 1.0048 |
Q2_0 is effectively lossless for ternary weights — the ternary values land exactly on three of the four 2-bit code points.
## Benchmarks
Evaluated with EvalScope v1.4.2 + vLLM 0.15.1 on NVIDIA H100. Full benchmark suite:
| Model | Size | Avg | MMLU-R | MuSR | IFEval | GSM8K | HE+ | BFCLv3 |
| :-------------------------- | ----------: | --------: | -----: | ---: | -----: | ----: | ---: | -----: |
| **Ternary Bonsai 1.7B** | **0.44 GB** | **58.47** | 52.9 | 50.8 | 70.1 | 74.2 | 51.8 | 51.0 |
| *1-bit Bonsai 1.7B (prior)* | *0.24 GB* | *49.60* | 43.2 | 45.1 | 63.0 | 66.3 | 45.1 | 34.9 |
| Qwen3 1.7B | 3.44 GB | **66.57** | 66.8 | 50.1 | 70.3 | 83.1 | 57.3 | 71.8 |
| Qwen3 0.6B | 1.19 GB | **48.02** | 47.5 | 41.5 | 62.8 | 64.1 | 30.5 | 41.7 |
| LFM2 1.2B | 2.34 GB | **46.73** | 52.9 | 25.4 | 77.5 | 62.2 | 36.0 | 26.4 |
| Gemma3 1B | 2.00 GB | **45.53** | 43.2 | 37.0 | 61.9 | 64.4 | 40.2 | 26.5 |
| Llama 3.2 1B | 2.47 GB | **39.88** | 47.2 | 29.2 | 47.7 | 49.0 | 35.4 | 30.8 |
## Intelligence Density
```
density = -ln(1 - score/100) / size_GB
```
| Model | Size | Intelligence Density (1/GB) |
| :-------------------------- | ----------: | --------------------------: |
| **Ternary Bonsai 1.7B** | **0.44 GB** | **2.001** |
| *1-bit Bonsai 1.7B (prior)* | *0.24 GB* | *2.832* |
| Qwen3 0.6B | 1.19 GB | 0.549 |
| Qwen3 1.7B | 3.44 GB | 0.318 |
| Gemma3 1B | 2.00 GB | 0.304 |
| LFM2 1.2B | 2.34 GB | 0.269 |
| Llama 3.2 1B | 2.47 GB | 0.206 |
## Citation
```bibtex
@techreport{ternarybonsai,
title = {Ternary Bonsai: 1.58-bit Language Models at 8B, 4B, and 1.7B Scale},
author = {Prism ML},
year = {2026},
month = {April},
url = {https://prismml.com}
}
```
## Contact
For questions, feedback, or collaboration inquiries: **contact@prismml.com**