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Table of Contents

1. Quick Start
2. The Front Panel (Panel page)
3. The Operator Console
4. User Terminals (TTY 1 / TTY 2)
5. The LP11 Line Printer (Printer page)
6. The VT11 Vector Display (Display page)
7. Storage (paper tape, disk & tape images)
8. Configuration (Config page)
9. Guest Operating Systems
10. Buttons, Shortcuts & Indicators
11. Troubleshooting
12. The Desktop App

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Quick Start

On your very first launch the emulator greets you with a short onboarding hint that explains what to do right away — which page to open, the mounted guest OSes and their boot commands:

The first-run onboarding hint.

The magic wand

In a hurry? Use the magic wand button in the top-right corner of the window. It stays on every page except Info. One click does everything:

1. Opens a picker listing every guest operating system (and the paper tapes).
2. Chooses one, switches to the operator console, and reboots the machine.
3. Types the boot command — and the login too, where the credentials are known (e.g. Unix V5: boot rk0 → unix → login root).

The quick-boot picker lists every guest OS and paper tape.

The wizard is prompt-aware: it watches the console output and types the login only when the guest actually prints login:, so slow boots with lots of output (e.g. 2.11 BSD) still reach the prompt reliably. Each guest also declares the machine profile it wants — e.g. RT‑11/RSX/RSTS enable the LP11 line printer, and Unix V5/BSD force a teletype console — so the wizard reconfigures the machine if needed and resumes the boot automatically. Every wizard boot starts on a fresh page (clean paper and clear screens), and a toast warns "Autoloading in progress — don't touch the teletype/keyboard" while the sequence is being typed.

While the wizard types the boot sequence, a toast asks you not to touch the teletype/keyboard.

The classic way

1. At the Boot> prompt, type boot rp1 and press ENTER.
2. BSD 2.11 will autoboot into multiuser mode. Login as root (no password).
3. Try ls, ps -aux, df — or compile a C program with cc.

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The Front Panel (Panel page)

Every switch, LED, and rotary knob of a real PDP‑11/70 is faithfully recreated. The Panel page is where you toggle in a bootstrap loader the way DEC engineers did in the 1970s.

The PDP‑11/70 front panel, powered on.

Front panel switch sequences

A simple light chaser — toggle this in to see the address and data LEDs dance:

Switch sequence: HALT, 001000, LOAD ADDRESS
                 012700, DEPOSIT
                 000001, DEPOSIT
                 006100, DEPOSIT
                 000005, DEPOSIT
                 000775, DEPOSIT
                 001000, LOAD ADDRESS, ENABLE, START

Restart the bootloader:

HALT, 120000, LOAD ADDRESS, ENABLE, START

The Bootstrap now! button refuses to start the machine while it is powered off:

Bootstrap now! requires the machine to be powered on first.

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The Operator Console

The operator console is what the PDP‑11 uses as its TT0: — the machine's own typewriter. Depending on the CONFIG page, it is either a Model 33 ASR teletype or a DECscope VT52.

Model 33 ASR teletype

The console is rendered as an authentic light-cream/beige Model 33 ASR: a paper roll behind the rising sheet, a glass carriage window, and a stamped Teletype Corporation logo on the lower face plate.

The Model 33 ASR operator console at the Boot> prompt.

• Keyboard. Round dark keycaps with light two-line legends — the base glyph centred, the CTRL-code name or shift symbol above — plus the historical special keys: ESC, LINE FEED, RETURN, DELETE, HERE IS (answerback), REPT (auto-repeat) and BREAK (asserts the console DL11 break condition).
• Upper Case Only. The on-screen keycaps always send upper-case letters. The physical keyboard folds a–z to A–Z only when the Upper Case Only CONFIG option is enabled (off by default, so 2.11 BSD receives lower case).
• Paper printing. Authentic nroff/man overstrike (^H) rendering: re-printing the same glyph gives bold, underscores give underline, and striking a different glyph leaves the real dark overstrike blot a hard-copy terminal makes.
• Margins. Long lines faithfully jam the carriage at the right margin (72 or 80 columns); characters overstrike the last column instead of wrapping. The paper width follows the selected width so a full line reaches the paper edge. The paper is anchored to the carriage and grows upward out of the top of the machine body; once its edge reaches the top of the window, a scrollbar appears and the view follows the freshly printed line.
• ASR reader/punch. Beside the machine sits the ASR tape reader/punch unit. Every byte echoed to the console punches a matching row of holes on an 8-track paper tape (tracks 1–7 = ASCII, track 8 = parity). As on a real ASR‑33 the punch is OFF by default — enable it from the CONFIG page or its own control.

VT52 as the console

When the console terminal is set to a VT52, the operator console becomes a DECscope with its authentic white/grey (P4) phosphor on a black tube — see User Terminals below for the full behaviour, which is shared.

A DECscope VT52 as the operator console, showing the Boot> prompt.

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User Terminals (TTY 1 / TTY 2)

Up to two user VT52 terminals (shown only when configured on the CONFIG page) let guest OSes that prefer video terminals run side by side. Each is drawn as an authentic slanted DECscope monoblock: an off-white moulded-plastic cabinet with a vent grille, a recessed screen in a deep bezel, and a plain plastic side panel with a raised ridge. Input comes from the physical keyboard, as on the original DECscope.

A user VT52 terminal (TTY 1) running an interactive session.

• Font. Text is rendered in the authentic fritzm/vt52 bitmap display font (monospace is the fallback until the webfont loads).
• Clear screen. Clear screen (ESC E) and form feed (^L) both wipe the display and home the cursor, so clear and multi-page nroff/man output start each page from the top row.
• CRT simulation (optional). A pure-CSS effect adds brightness flicker, scanline shimmer and a vertical-hold roll band.
• Text mode (optional). Renders the terminal as a plain text field instead of the canvas, enabling native text selection and Windows Clipboard (Ctrl+C/Ctrl+V/ right-click paste) for fast source-code entry — at the cost of the SGR emphasis rendering.

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The LP11 Line Printer (Printer page)

The LP11 is an animated line printer on wide 132-column paper (72/80/100/132 selectable). It has no keyboard — it only prints. Use the Print button to send the accumulated jobs to the real OS printer via the system dialog, or Save .txt to export the output (page breaks are kept as \f markers).

The LP11 line printer printing a job listing.

• Speed. Like the real LP11, it echoes characters far faster than the Model 33 ASR console teletype (which keeps its authentic ~33 cps pacing), printing at close to the original's ~300 lines/min.
• DONE handshake. The LP11 honours the historical DONE handshake: writing LPDB clears DONE and re-asserts it as each character is consumed by the mechanism, so a guest print job is throttled at printer speed.
• OFF LINE. When the printer is OFF LINE (or powered off), the controller latches a sticky ERROR flag in LPCS while keeping DONE set — so a guest OS driver reports an error (e.g. ?LP0: I/O error) instead of silently discarding the job.
• Form feed. The LP11 honours form feed (FF, 0x0C) — the 2.11BSD spooler (lpr/ lpd) sends FF between jobs so each starts on a fresh page: it fills the rest of the sheet (66 lines at 6 LPI) and closes it with a dashed fold/perforation marker.
• Tabs & paper. The carriage advances to the next 8-column tab stop on TAB, and the paper is sized to the configured print width (centred in the machine body). The cabinet auto-scales down proportionally to fit the window when it gets too small, and the rising fanfold paper climbs the same fraction of the window after scaling.

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The VT11 Vector Display (Display page)

An optional DEC VT11 vector-graphics display processor on its own green-phosphor CRT page (1024×768 logical resolution, auto-scaled to fit the window), enabled from the CONFIG page. Lunar Lander uses it — the quick-boot wizard enables the display and switches to the Display page automatically.

Lunar Lander drawn on the VT11 vector-graphics CRT.

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Storage (paper tape, disk & tape images)

The Storage page manages every kind of storage media:

The Storage page: paper-tape reader, drop zone and mounted images.

• Paper tape reader. A file selector for the #ptr device. Load BASIC‑11, ODT‑11, ED‑11, or Lunar Lander from simulated paper tape — then boot with boot pr.
• Drag & drop drop zone. Drop any disk/tape image here — .dsk, .tap, .ptap and their .zst-compressed forms are supported.
• Mounted images / Unmount list. Shows currently mounted images and lets you unmount them. Mounted images persist in browser storage (IndexedDB) and are re-mounted automatically on the next launch — changes to disk contents survive across sessions.

Note: the paper-tape reader is driven by the console bytes — every byte echoed to the console punches a matching row of holes on the ASR paper tape.

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Configuration (Config page)

The Config page controls the emulated peripherals and is persisted between sessions. The form is split into four tabs, with the Apply and Restore defaults actions in a bar below the tabs:

Leaving the Config page with uncommitted changes asks for confirmation, so nothing is lost silently:

The emulator warns before leaving Config with uncommitted changes.

Structural changes (console type, terminals, printer, VT11 display) are committed with Apply, which restarts the machine so the emulated hardware matches the configuration. Print widths, teletype speed, the Upper Case Only flag, key click, reverse video, CRT effects, VT52 text mode, machine hum and the photo backdrop apply immediately. Restore defaults fills the form with factory values (committed by Apply).

The hum is synthesized with Web Audio on its own audio channel, so it never cuts off the teletype/printer or the VT52 key-click sounds.

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Guest Operating Systems

The emulator ships with ready-to-boot disk and tape images. Just type boot at the Boot> prompt — or pick one with the magic wand.

Disk	Operating System	How to Boot
RK0	Unix V5	boot rk0 → unix → login as root
RK1	RT‑11 v4.0	boot rk1
RK2	RSTS V06C‑03	boot rk2 — login 11,70 password PDP
RK3	XXDP (diagnostics)	boot rk3
RK4	RT‑11 3B Distribution	boot rk4
TM0	RSTS 4B‑17 (tape)	boot tm0 — follow ROLLIN restore procedure
RL0	BSD 2.9	boot rl0 → rl(0,0)rlunix → CTRL/D → login root
RL1	RSX‑11M v3.2	boot rl1 — login 1,2 password SYSTEM
RL2	RSTS/E v7.0	boot rl2 — login 11,70 password PDP
RL3	XXDP (extended)	boot rl3
RP0	ULTRIX‑11 V3.1	boot rp0 → CTRL/D → login root
RP1	BSD 2.11	boot rp1 — autoboots to multiuser, login root
RP2	RSTS/E v9.6	boot rp2 — answer prompts, login 11,70
RP3	RSX‑11M v4.6	boot rp3 — auto-logs 1,2 SYSTEM
RP4	RSTS/E v10.1	boot rp4 — answer prompts, login 11,70

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Buttons, Shortcuts & Indicators

Switching pages

Use the sidebar to switch between:

• Panel — the front panel with switches and LEDs.
• Console — the operator console: a Model 33 ASR teletype (or a DECscope VT52, when the console terminal is a VT52).
• TTY 1 / TTY 2 — user VT52 terminals, shown only when configured.
• Printer — the LP11 line printer page, shown only when configured.
• Display — the VT11 vector-graphics CRT page, shown only when configured.
• Storage — paper-tape reader, disk/tape image import and mounted images.
• Config — configure the emulated peripherals (persisted between sessions).
• Info — detailed instructions and OS reference.

Floating controls

Control	Where	What it does
Magic wand	Top-right corner (every page except Info)	Quick-boot picker — chooses a guest OS, reconfigures, reboots and types the boot/login.
REBOOT	Top-left corner, just right of the sidebar	Round button with a restart icon. Restarts the machine; when Auto-boot is enabled it also boots the built-in default loader. By default a confirmation dialog asks first, with a "Don't show this warning anymore" option.
Mute	Bottom-left corner, just right of the sidebar	Round button that toggles all sounds at once — hum, teletype/LP11, paper feed/tear, key clicks and the bell. State is persisted with the rest of the configuration.
Fullscreen	Bottom-right corner of the window	Floating button that hides the browser/system chrome (address bar, OS window frame, taskbar) while leaving the emulator UI untouched. Press again or Esc to return.

The REBOOT button asks for confirmation by default.

Sidebar activity lamps

Each output sidebar button has a small blinking green LED in its top-right corner: it pulses while the PDP‑11 writes output to that console/terminal (and blinks for the whole print job on the Printer button), then switches off about half a second after the output stops.

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Troubleshooting

An image cannot be loaded

If a guest OS image cannot be fetched completely — a big BSD image dropped by the hosting server mid-download, or an image that is not bundled in the Minimal desktop build — the emulator doesn't stall silently. A dialog in the same shared modal style as the first-run hint explains that the image is incomplete and offers Open Storage, which jumps straight to the drop zone for a manual drag & drop of the downloaded file.

The wording adapts to the environment: a page opened as a local file:// explains that the browser blocks fetching the media directory (and suggests a local web server), while the Tauri Minimal build explains that the image is not shipped and points to the drop zone.

An incomplete image triggers this dialog with an Open Storage shortcut.

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The Desktop App

Prefer a native app? The same emulator is packaged as an offline desktop application for Windows x64 with Tauri. Two installer variants are available:

Variant	Ships	Notes
Minimal	rk0, rk1, bootcode	Small download (~3 MB). All other images are dragged & dropped at runtime.
Full	every image — RK/RL/RP/RA disks, TM tapes, all paper tapes	Larger download, but all 16 guest OSes boot offline with zero extra steps.