PLAY THE HARDWARE / 6502

Two 6502 computers you can run in a browser

The 65uino and ABN6502 r2 began as physical circuit boards. Now you can boot their real firmware, press their controls and explore their internals without installing anything. Start from the 6502 Emulators landing page, or jump straight into either machine.

Start with the 65uino

65uino emulator with its real BIOS displayed on the board's OLED
The board photograph is the backdrop; the OLED, button and pins are interactive.

The 65uino emulator models Anders Nielsen’s 6507-based board in the Arduino Uno form factor. Its 6532 RIOT supplies RAM, I/O and a timer. The original BIOS draws on a 128 × 64 OLED, and the virtual button navigates its menu. Try the bundled Hello OLED demo, pull an available GPIO input low, or type in the serial terminal. Pause, step, and inspect registers in the CPU monitor. You can also open a raw ROM image locally in your browser; it is not uploaded.

Try this: launch the emulator, wait for the BIOS menu on the OLED, then hold and release BTN to select an item. The on-screen controls work on a phone too.

Move up to the ABN6502 r2

ABN6502 r2 emulator displaying text from the real ROM on a green VGA monitor
The ABN6502 r2 runs its original 32 KiB ROM at the board’s 2 MHz CPU clock.

The ABN6502 r2 emulator is a larger 2 MHz 6502 computer. It boots the real 32 KiB main ROM, uses the real 2 KiB character ROM, and draws a 512 × 256 green VGA image from video RAM. Type into the screen to interact with the firmware. Press F1 for its memory monitor, then PgDn to move from the cleared start of zero page to live variables. Press F4 to enter the bundled BASIC. On a phone, tap the screen for the soft keyboard and use the on-screen key drawer for F-keys and navigation.

The browser sends PS/2 set-2 scan codes to the ROM’s input buffer, where the original firmware translates them. That is a functional keyboard bridge, not electrical PS/2 timing simulation. The RF module is not modeled, and the VIA implements the stock ROM’s used registers rather than every 6522 feature. Neither emulator claims to be a cycle-exact substitute for the physical board.

Why try both?

The machines show two different ways to build around the 6502 family. The 65uino is a compact one-button, OLED-and-GPIO learning board; the ABN6502 adds video memory, VGA text and a keyboard. You can see what the actual firmware does before buying or assembling hardware. If you are new to address buses and chip selection, our beginner’s 6502 computer guide explains the underlying ideas.

From emulator to workbench

Explore the 65uino kit or the assembled ABN6502 r2. The emulator hub also links the PCB variants and both Hackaday project pages. Emulator code is MIT licensed; bundled firmware and board photographs retain their separate CC BY-NC 4.0 terms. Source archives are linked from each emulator.