TeensyROM+ (PCB v0.4) — the next generation of the TeensyROM multi-function cartridge for Commodore 64/128. This is a fully assembled and tested TeensyROM+, including a pre-programmed Teensy 4.1 — no soldering, no flashing, nothing to configure.This is the complete package: your TR+ cartridge, snapped into a low-profile 3D-printed case (designed/manufactured by 0ldSkull Retro), plus a 32GB SD card preloaded with games, demos, and utilities ready to take full advantage of everything TR+ can do — just plug in and go.

TR+ runs 100% of the standard TeensyROM feature set from the same firmware base — nothing is removed or downgraded from the original TR. TR+ simply adds a genuinely new tier of capability on top, unlocked by real bus-mastering DMA hardware that the original TR doesn't have.

TR+-Exclusive New Features:

• Kernal Replacement — load a custom KERNAL ROM image with zero hardware modification. Pick any KERNAL right from the file browser; your choice is remembered automatically.
• 512KB REU (RAM Expansion Unit) — a real REU your C64 software can detect and use. Pre-load an REU image from SD/USB, and save its live contents back out with one button press.
• Freezer Cartridge Support — Action Replay, Retro Replay and Super Snapshot V5 (PAL and NTSC) emulated natively. Freeze into it on demand with the dedicated "Alt" button.
• Remote DMA Memory Access — real-time read/write of C64 memory from an external app over Serial or Ethernet. This is the engine behind projects like c64cast (streaming video/audio straight through your C64).
• Battery-Backed Real-Time Clock — built-in coin-cell (CR1225) holder keeps the correct time through power cycles, no soldering required. No Ethernet re-sync needed once it's set.
• External Reset Detect — an external reset (C64U button, User port, etc.) drops you right back into the TR menu, same as pressing the TR button.
• Programmable Alternate Button — a second "Alt" button assignable to AutoLaunch (jump straight into your favorite title), Pause/Unpause, jump to menu, reboot, or disable.
• Full Expansion Port Test Suite — validates every cartridge port signal individually (address/data bus, DMA, BA, R/W, IRQ, NMI, and all cart control lines) — only possible with TR+'s true bus-mastering hardware.

Everything the Original TeensyROM Does (all included, none lost):

• Instant PRG/P00 loading and CRT ROM emulation from USB drive, SD card, or internal flash
• MIDI USB Host & Device — play your SID chip from a USB MIDI keyboard or DAW; Sequential, Datel/Siel, Passport/Sentech, and Namesoft MIDI cartridges emulated
• Custom ASID Player — stream .SID or .MIDI files straight from a modern PC to real SID hardware
• Ethernet internet interface — connect to Telnet BBSes, use the built-in web browser to surf/search/download, Swiftlink + 38.4k modem emulation
• NFC Launch System — tap an NFC tag for instant, old-school-cartridge-style loading
• Remote control via the cross-platform TeensyROM-Web app or Command Line Interface
• SID File Player with voice muting and speed control
• Bitmap picture viewer, PETSCII/text viewer, custom BASIC commands, Autolaunch, and more
• >100 files built-in: SIDs, games, utilities, tests, and pictures — ready to plug and play, no external media required to get started
• Firmware updates straight from SD/USB — just drop the .hex file, no special software needed

Compatibility: Compatible with C64 and C128 machines/variants — NTSC and PAL both supported. Fully validated on C64, C64C, SX-64, and C128, plus modern reproductions including the C64U/Ultimate 64, Mega65 (r5+), and Reloaded MKII.

What's in the box:

• Assembled & tested TeensyROM+ cartridge (PCB v0.4)
• Low-profile 3D-printed enclosure
• 32GB SD card, preloaded with a curated collection of games, SIDs, demos, and utilities.

Firmware is actively developed and updated — free firmware updates for the life of the device, just drop the file on the SD card.

Docs, demos & community:

• Full documentation, feature guides, and firmware revision history: TeensyROM on GitHub
• Demo videos on YouTube, including an NFC reader demo
• Questions, feature discussions, and updates: come say hi on the TeensyROM Discord Server

By purchasing from me — the designer — you're directly supporting continued development of this project. Thank you!

-Travis / Sensorium