Exploration ·
Start with one transistor switching an LED, wire switches into gates, gates into an adder, feedback into memory, and memory plus a clock into a tiny CPU — then watch a real 6502 run a program you can read byte by byte.
Tool ·
An Acorn Electron in your browser — the Electron ULA with MODEs 0–6, its palette registers and the RAM contention that slows the CPU in MODEs 0–3, the single sound channel, the keyboard matrix and UEF tapes through the ULA's cassette interface — with your own Acorn ROMs or an open stand-in OS. Type BBC BASIC, write 6502 assembly and debug it with breakpoints beside the code.
Tool ·
A Commodore PET in your browser — the 2001, 3032 and 4032 with the 40-column screen, or the 80-column CBM 8032; graphics or business keyboard, green, white or amber phosphor, the CB2 beeper, the 6520 PIAs and the 6522 VIA. It boots Microsoft's open-source BASIC 1.1 on a KERNAL written for this site, or your own ROMs; loads PRG, D64 disks and TAP tapes, and saves to them. Write 6502 assembly and debug it beside the code.
Tool ·
A Commodore VIC-20 in your browser — PAL or NTSC, unexpanded or with 3 to 35 KB of expansion, the VIC chip's 22 × 23 screen, colours, multicolour and custom characters, its three voices and noise, both 6522 VIAs, keyboard and joystick (gamepad too). It boots Microsoft's open-source BASIC 1.1 on a KERNAL written for this site, or your own ROMs; loads PRG, D64 disks, TAP tapes and cartridges, and saves to disk and tape. Write 6502 assembly and debug it beside the code.
Tool ·
An Oric Atmos or Oric-1 (16K or 48K) in your browser — the ULA's 40×28 text and 240×200 HIRES with serial attributes, the 6522 VIA, the AY-3-8912, the keyboard matrix, and .TAP tapes loaded and saved at once through ROM traps. Write 6502 assembly and debug it with breakpoints, stepping, registers, memory and chip views. Load your own BASIC ROM; without it a stub monitor written for this site runs.
Tool ·
An Apple II+ or IIe in your browser — text, lo-res and hi-res with NTSC artifact colour or a monochrome monitor, the speaker, and a Disk II that reads .DSK, .DO, .PO, .2MG and .NIB images as real GCR nibbles. Write 6502 assembly and debug it with breakpoints beside the code, stepping, registers, memory and the soft switches. Load your own ROMs; without them a stub monitor written for this site runs.
Tool ·
A BBC Micro Model B in your browser — 6845 CRTC and video ULA (MODEs 0–7 with MODE 7 teletext), both 6522 VIAs, the SN76489, UEF tapes and SSD/DSD discs through an emulated 8271 — with your own Acorn ROMs or an open stand-in OS. Type BBC BASIC (inline [ ] assembler included), write 6502 assembly, and debug with breakpoints beside the code, stepping, OS call labels and chip views.
Tool ·
A Commodore VIC-20 (PAL or NTSC, with memory expansions and cartridges) or PET 2001 / 3032 / 4032 / 8032 on one page — the VIC chip's video and sound, the 6522 VIAs and 6520 PIAs, the keyboards, PRG, D64 and TAP files. Boots Microsoft's open-source BASIC 1.1 on a KERNAL written for this site, or your own ROMs. Write 6502 assembly and debug it with breakpoints beside the code.
Tool ·
Write Atari 2600 (VCS) programs in 6502 assembly — DASM-style, with vcs.h and macro.h built in — assemble them to a 2K, 4K or 8K cartridge, and run them in an emulator with a debugger: step by instruction, scanline or frame, breakpoints, registers, RAM, TIA state, the beam position, and a frame-timing check.
Tool ·
An Atari 800, 800XL or 130XE in your browser (atari800 in WebAssembly, the free Altirra OS and BASIC) — run disks, programs, cartridges and tapes; type and save BASIC; write 6502 assembly and run it, or call it from BASIC with USR; and debug anything that runs with breakpoints, stepping, registers, memory, the ANTIC/GTIA/POKEY/PIA registers and the display list.
Tool ·
A Commodore 64 in your browser — the cycle-stepped chips emulator in WebAssembly, booting the free MEGA65 Open ROMs (or your own). Run PRG, D64, T64 and TAP files; type and save BASIC; write 6502 assembly and run it, or call it from BASIC with SYS; and debug anything that runs with breakpoints beside the code, stepping, registers, memory, and the VIC-II, SID and CIA registers.
Tool ·
Assemble and disassemble 6502 and 65C02 code in the browser, with labels, local labels, expressions, and an optional undocumented-opcode set; download raw binaries, Atari binary-load files, or C64 PRGs; search the full opcode table with cycles and flags.