Picocomputer 6502¶
Pure 6502. No governor. No speed limits.
The Picocomputer 6502 is an open source, modern-retro gaming computer built around a WDC 65C02. The design philosophy is simple: keep the soul of programming a 6502 and 6522, then rethink everything else. The hardware and the software are both open, and the whole design is friendly to DIY builds.
Community¶
Most of the action is on Discord, where you can also grab ROMs. Subscribe to the YouTube channel and share the project around while you’re at it.
Specs (RP6502-PICO)¶
Core — WDC 65C02 CPU and 65C22 VIA, variable from 0.1 to 8.0 MHz
RAM — 64 KB system plus 64 KB extended
ROM — 1 MB of onboard flash for installing and auto-booting
Video — VGA and HD output, 16-bit color tile and sprite engine
Sound — PSG (8 voices) or OPL2 FM (9 voices)
Storage — Full Speed USB flash and 3.5” floppy drives
Clock — real-time clock with automatic Daylight Saving Time
TRNG — true random number generator
Connections (RP6502-PICO)¶
Console manifold — reach the console over telnet, serial, or direct attach
Wi-Fi — NTP time sync, telnet server, and Hayes modem emulation
Bluetooth LE — keyboards, mice, and gamepads
USB host — keyboards, mice, gamepads, hubs, UART serial, MIDI, NFC, floppy and flash drives
USB device — serial console access with no driver needed (CDC ACM)
Writing Software¶
A ROM here is one .rp6502 file holding a program, its assets, and
the 6502 vectors. Nothing is burned into a chip — this file prepares RAM
before the 6502 starts and delivers assets to the program.
Protected OS — 32-bit operating system that uses no 6502 RAM
FAT filesystem — read and write files on the machine’s drive
POSIX-like API — a familiar C library for portable code
cc65 and llvm-mos — SDK for either 6502 compiler
International — keyboard layouts and OEM code pages
Get a Machine¶
The original idea — use a modern CPU to remove the friction of enjoying the best parts of the 6502 — carries forward on every host. What changes is which modern CPU, and how much of the machine it is asked to be.
RP6502-PICO: the one you build. 100% through-hole construction, no IC programmer required. Hundreds of people have built one, typically for under $100 USD. Prefer not to solder? You can have a unit manufactured in China instead. Every part is currently in production, and the Raspberry Pi Pico 2 is guaranteed through at least January 2040.
RP6502-EMU: software emulation, for Windows, macOS, Linux, Android, and the browser. The host CPU runs everything natively except a small emulator for the 6502 and 6522. There’s a playable one on that page — you can be running 6502 code in about two seconds.
RP6502-FPGA: hardware emulation. The whole machine in gates, on an Analogue Pocket today and MiSTer next. Mostly RTL, with a RISC-V embedded to run the OS bridge to the host platform.
All machine types are treated equally. Our unit and functional CI testing framework runs all code against the same tests whether it’s declarative RTL or imperative C. The guarantees all machine types support all sound systems and video modes equally.
Things that matter, the 6502, 6522, and video timing, are cycle accurate on all machines. But some hosts may have unusual limitations or advantages. For example, the RP6502-EMU is often run on a machine with NVMe storage many orders of magnitude faster than a, RP6502-PICO’s 12 Mbps USB.
Read the docs¶
RP6502-SDK: writing software, from a new project to a running program. Start here.
RP6502-RIA: the register map and every device reached through it — the interface adapter, in the spirit of the classic CIA, VIA, and ACIA chips. Assumes you are comfortable at the bus level.
RP6502-RIA-W: setting up Wi-Fi, Bluetooth, telnet, and the Hayes modem.
RP6502-VGA: canvases, video modes, sprites, and the scanline programming underneath.
RP6502-TERM: the console, its escape sequences, and the line editor.
RP6502-OS: the system calls, the ABI, and the C library sitting on them.
