Trashboy

A pocketable TRS-80 Model III/IV. Yes, really.

What is this?

A handheld TRS-80 Model III / IV emulator running on an ESP32-S3 board with a 640×480 RGB LCD.

It runs at original-hardware clock speed — 2.028 MHz for Model III, 4.055 MHz for Model IV — synchronised to wall-clock time so games play at their original speed. The 8 × 12 (M3) and 8 × 10 (M4) glyphs are blitted into an LVGL canvas with 90° rotation, so the portrait panel reads as a landscape Model III screen.

Hardware

Software stack

• ESP-IDF — Official ESP32 software stack
• LVGL v9.1 in LV_DISPLAY_RENDER_MODE_PARTIAL with software rotation done inside the flush callback (the panel has no hardware rotation, and lv_display_set_rotation alone only swaps reported dimensions). An adaptive flush callback skips the rotation entirely when the emulator is running, since its TRSCanvas pre-rotates glyphs into an unrotated buffer.
• libz80 Z80 emulation core in components/ptrs/, derived from apuder/pTRS-80.
• RetroStore C SDK (components/retrostore-c-sdk/, git submodule) for fetching downloadable game media. HTTP and decode buffers live in PSRAM to keep internal SRAM available for BT/Wi-Fi coexistence working memory.
• esp-hid wrapping BT Classic + BLE for the keyboard host.
• TRS-IO / TRS-LIB (components/trs-io/, components/trs-lib/) for on-screen menus, the F5 settings UI, and TRS-80 system I/O glue.

Want the full picture? See firmware/ARCHITECTURE.md — boot sequence, task layout, the rotation handoff between splash and emulator, memory placement rules, and lessons-learned annotations.

Build & flash

# Once per shell session:
source ~/.espressif/tools/activate_idf_v6.0.1.sh

cd firmware
idf.py set-target esp32s3        # only the first time
idf.py build
idf.py -p /dev/ttyACM0 flash monitor

On WSL2, the USB device routing is its own little adventure — see firmware/wsl.md.

Repo layout

.
├── assets/         Artwork (logo PNGs)
└── firmware/       ESP-IDF project — the action lives here
    ├── main/         app_main, LVGL UI, splash, Wi-Fi setup,
    │                 RetroStore browser, MCP23017 buttons, input test
    ├── components/   Z80 core, TRS-80 emulator, BT keyboard,
    │                 RetroStore SDK, TRS-IO, TRS-LIB
    ├── scripts/      Serial logger, asset rotation helpers
    ├── ARCHITECTURE.md
    └── wsl.md

Status

Active development on the lvgl9 branch. Recent direction: ESP-IDF v6 migration, MCP23017 board buttons over IRQs, GT911 touch driver, RetroStore game launching with PSRAM-backed buffers, an adaptive flush callback for the LVGL pipeline.

_{Not affiliated with Tandy or Radio Shack. The TRS-80 trademark belongs to whoever owns it now.}