SUPDUP, Telnet, and the Genera Terminal program

Entry points and window reuse

The selected public System 46 LMWIN implementation registers System-S for Supdup, System-T for Telnet, and both names in its Create menu. The separate LMIO/LMIO1 Escape-N dispatcher described below is an older shadow lineage and is not silently added to that selected profile.

Maintained System 303 declares the SUPDUP system and provides these source-visible paths:

The default *SUPDUP-MODE* is true, so the ordinary Lisp entry chooses a separate window. The distinction is architectural, not just geometry: bound operation borrows the current process and substitutes its overlay for the caller's window, while a separate window owns its normal type-in and type-out processes.

The current maintained file has no System-S or System-T registration. The preserved base band's live System Help likewise listed Top-L, E, I, L, and P but not S or T. An earlier maintained supdup.lisp.322 did register S/T, so that is a versioned lineage difference rather than permission to add the keys to the selected current source profile.

The older System 46 LMIO Escape-N dispatcher exposed a numerical policy: no argument or zero found or made Supdup; argument 1 selected Telnet; 2 made a new Supdup; 3 made a new Telnet; and a list/precomma argument selected an existing instance. That exact dispatcher is recovered in the public on-line Help corpus. It is shadow-lineage evidence, not part of the selected System 46 LMWIN implementation and not a claim that System 303 retains the same Escape-N UI.

Shared two-process architecture

BASIC-NVT holds the connection, network stream, output buffer, local escape character, optional terminal stream, and connection target. It requires protocol subclasses to implement connect, greeting consumption, raw output, and translated output. A type-in process reads keyboard events and writes the network; a type-out process reads the network and updates the screen. An output lock serializes writes because local escape commands can also emit protocol traffic.

The flavor branches are:

Selection and exposure lazily reset the two processes, avoiding cold-boot paging for an unused terminal. A disconnected window suppresses input/output notification. A connected window reports remote close, loss, host-down, and unknown connection states back into the type-in side as a local error reason, then returns to the host prompt.

Host and contact syntax

At the disconnected prompt, Help describes the same grammar that PARSE-PATH implements:

There is an important lineage discrepancy. The nearby maintained source comment and Help prose call explicit Internet socket numbers octal, while PARSE-NUMBER is passed radix 10 for slash-suffixed Internet socket values. The executable code therefore wins for System 303: the source documentation is stale on that point. Default Supdup and Telnet sockets remain written as octal constants corresponding to their historical service ports.

Complete local Network-key inventory

The default escape is the physical Network character. Pressing it displays a temporary CMND--> prompt on the bottom line and consumes one following command. The complete maintained dispatch is:

E is a source-only command. The maintained implementation handles it, but the computed Network-key Help does not list it. Its immediate effect is to restore normal keyboard interpretation rather than super-image pass-through. No manual claim is inferred about how a user was expected to re-enter super-image mode after using it.

SUPDUP behavior

Supdup connects to the SUPDUP Chaos contact or its historical gateway socket. It sends the peer a packed terminal-description block containing dimensions, character cell metrics, scrolling and option flags, followed by the machine's Finger location. It then consumes an ASCII greeting until the SUPDUP no-operation delimiter.

The maintained display dispatch covers the following effect classes at its defined code positions:

Function keys and bucky bits are translated into the ITS 12-bit character space. Nonzero modifier bits are sent through the Intelligent Terminal Protocol escape sequence; the protocol escape byte itself is doubled. Network L emits SUPDUP's two-byte logout sequence before closing.

Two implementation limits are not evident from the small Help table:

• a connected Supdup window refuses size changes because the advertised geometry would become false; and
• Supdup deliberately refuses local More processing. The source says enabling it can wedge the output process so completely that input cannot release it.

Character insertion/deletion capability is also not always advertised. It is enabled for system types such as WAITS and Multics where the remote implementation needs or benefits from it; otherwise the source favors faster output over the extra capability.

The default maintained SUPDUP-FLAVOR is ordinary SUPDUP. Recording and local editing are alternate flavor behavior selected only when that flavor variable is changed; their presence in the file does not make them defaults. GT40 and ARDS also retain partly global state, so separate windows can interfere in ways the small Help surface does not disclose.

Telnet behavior

Telnet shares the NVT window lifecycle but performs Internet NVT translation and option negotiation. The maintained implementation:

• sends CR as CRLF;
• doubles IAC in new-Telnet mode;
• negotiates Echo, Suppress Go Ahead, Transmit Binary, Timing Mark, Logout, and SUPDUP-OUTPUT;
• locally echoes when the remote side is not echoing;
• maps Lisp-machine function characters and Control/Meta bits into NVT codes;
• treats CRLF as newline and a bare CR as cursor-to-column-zero;
• rings the local remote-terminal bell for Control-G outside binary Imlac mode;
• can switch the output stream into SUPDUP-OUTPUT subnegotiation; and
• can send Telnet Interrupt Process plus Data Mark through the Chaos-to-Internet gateway's interrupt packet convention.

When SUPDUP-OUTPUT is active, the window additionally reports mouse position and buttons in the peer's expected text encoding. The who-line documentation changes to advertise buffer-like pointer actions in that mode. This is protocol-specific remote UI support, not a general presentation system.

Maintained-tree variants that are not separate applications

window/telnet-code.lisp and window/telnet-front-hack.lisp are source-present compatibility experiments. The former contains the special four-byte Lisp-machine character stream and server/client override. The latter is a divergent copy of the current Supdup/Telnet implementation: it defaults overprint true, uses older syntax and :characters nil, and adds direct raw-Telnet output wrappers. It does not carry the four-byte server work. Neither file is selected by the declared SUPDUP system or registered as another user application. Their presence documents experimental integration branches, not a third terminal product.

One official Terminal activity

Genera registers the official activity and Create-menu name Terminal, adds Select T, and creates an NVT-WINDOW. The source explicitly says “NVT” is too specialist for the public name. The entry routes do not share one allocator: Create always makes and selects a fresh window; Select T uses the generic activity-selection policy and Control-Select T forces creation; Peek and direct remote-login requests scan the previously selected array and reserve the first idle Terminal, creating one only if none qualifies. A window counts as in use when it already has a network stream or a pending connection target.

The live release inventories establish all three registrations in the inspected world:

Window and process architecture

The Genera frame still owns separate type-in and type-out processes, but its data path is decomposed:

keyboard/presentation input
  -> local Network-key escape filter
  -> login-protocol type-in filters
  -> network service stream

network service stream
  -> protocol negotiation/output filters
  -> terminal simulator
  -> viewport/recording stream
  -> Terminal screen

NVT-WINDOW owns the screen, Dynamic Windows typeout surface, network stream, filter chains, output recording, wallpaper file, connection options, and processes. Protocol-specific mutable state lives in lazily created state blocks rather than in one Telnet subclass. The output process notices state changes with a tick so option changes can rebuild or reset the relevant filters safely.

Connecting and all connection keywords

At Connect to host:, Return after a host accepts defaults. Space after the host opens keyword parsing. The complete source-defined keyword surface is:

The installed manual documents all except Record Output in its connection-keyword list, although its next section describes the behavior output recording enables. The source makes the option and its default explicit.

Complete Terminal-specific command inventory

The source defines sixteen commands in the Telnet Command Processor table. Connect is deliberately a parser template: calling its body signals an error, while the Terminal top-level uses its argument parser and then invokes the window's real :CONNECT method. This is an implementation detail hidden behind an ordinary prompt.

Network-colon enters extended-command parsing. Network-Meta-W invokes the shared “push all marked text onto kill ring” accelerator. The installed keyboard manual instead says that Meta-W “wipes” marked text, while both Terminal's canned Help and the command symbol identify a kill-ring push. The source and live command definition support “push”, so “wipes” is treated as a documentation error.

The canned extended list contains Set Terminal Simulator Type, Set Escape Character, Set Wallpaper File, Set Overstriking, Send File, and Send String. It omits several commands that nevertheless exist in the table: Receive File, Set Output Recording, Set Local Echoing, and the parser-only Connect command. A complete source audit must therefore not equate Network-Help's curated list with the full command table.

The exact connected Network reader has 63 normalized fixed accelerator cells: 37 Standard Arguments cells, 12 unshifted argument cells, three full-command cells, and 11 Terminal-local cells. It compares letters case-insensitively. Fixed bindings win before the configurable literal-escape test, so changing the escape to A, colon, a digit/argument key, or another fixed cell does not override that command. Rubout normally cancels, but becomes literal when it is the configured escape. Help alone reprompts; unknown input beeps, clears the pending argument, reports, and reprompts.

Only Network-M accepts a numeric argument among local leaves: absent toggles, zero disables, and every nonzero value including a negative one enables. The source reader holds a (kind,value) pair, initially (nil,1): minus resets it to (:sign,-1), Control-U replaces the kind and multiplies the current value by four, Infinity uses 2^40 * signum(value), and the first digit after any nondigit kind replaces the magnitude using signum(value). Consequently Control-U then minus resets to -1, zero then Infinity stays zero, and minus-0 followed by another digit becomes positive. The disconnected Connect prompt, extended commands, pathname/format arguments, and Network-X are separate CP/Input Editor or Accepting Values contexts with their own complete inherited trees. The Genera companion is the normative exhaustive inventory.

Dynamic Windows behavior and pointer controls

With output recording enabled, the manual documents a small user-facing subset. The effective surface is larger because the Terminal participates in the Dynamic Windows 96-cell pointer resolver and conditional handler registries:

The Terminal does not attach semantic application-object presentation types to remote text. Its input loop does create a narrow TERMINAL-INPUT context so selected recorded text can be converted back into characters, and its prompts, Help, commands, typed arguments, and Accepting Values panel use Command Processor/Dynamic Windows presentations. This reconciles the source with the manual: semantic remote objects are absent, but presentation-based control paths are not.

The Release 7 manual describes protocol-dependent history depth: Telnet and CTERM can retain the full recording, while SUPDUP, 3600-LOGIN, and VT100 simulation expose only one screenful because remote cursor addressing and destructive operations make deeper scrollback misleading. The selected readable source and System 452.22 runtime have not yet confirmed those exact per-protocol limits; they remain the normative specification's TODO-ORACLE-G-HISTORY-*, not a source/runtime fact.

Login protocols and filter composition

The exact file declares seven login protocols:

These desirability values participate in service selection; they are not measured performance rankings. Host and service declarations can override the generic choice.

Terminal simulators

Four simulator types are registered in this source boundary:

The shared ANSI simulator parses a selected ESC/CSI subset, selects character sets, controls cursor position and erasure, and sets character attributes. Unsupported sequences are consumed. SGR examines only the first parameter; blink state is stored but has no selected drawing branch. VT100 adds only the four directional input translations to ESC [A through [D. ESC = and > mutate a keypad-mode slot that the selected source never reads; device reports, cursor-position reports, broad keypad/function translation, and many ANSI/VT52 operations remain unimplemented comments. Ambassador and VT100 specialize the base without filling those gaps. Simulator choice can be a host default or a connection option and can be changed while connected through Set Terminal Simulator Type.

SUPDUP and Telnet compatibility retained inside Genera

Genera's SUPDUP state block implements the same broad effect families as System 303: cursor movement and reports, clearing, CR/LF/space/backspace, insert/delete lines and characters, scrolling regions, bell, reset, attributes, graphics, GT40, ARDS, and SUDS. The implementation is reorganized around a SUPDUP-FILTER, state block, viewport, and separate graphics state rather than direct calls from a BASIC-SUPDUP window.

The Telnet state block recognizes Echo, Suppress Go Ahead, Timing Mark, Transmit Binary, Logout, and SUPDUP-OUTPUT negotiation. NVT ASCII input quotes IAC and converts Return to CRLF. Unsupported negotiations receive WONT or DONT rather than being silently accepted. SUPDUP-OUTPUT can feed bounded embedded SUPDUP display records through the same state block.

Source findings absent or easy to miss in the manuals

• The official public name is intentional. A source comment says Terminal was chosen because “NVT” would not mean much to a non-network specialist.
• Connect is not an executable command body. It exists to reuse Command Processor parsing and intentionally errors if called directly.
• The Help list is curated, not exhaustive. Four live command definitions and the Network-F accelerator fall outside its printed lists.
• Receive File exists beside Send File. Its default format is XMODEM, while raw Send File defaults to raw text. Transfer temporarily coordinates the type-out process rather than letting terminal decoding consume the file protocol.
• A mouse-position translator is reader-commented out. The file contains a proposed blank-area Left gesture that would send coordinates, but #|| ... ||# excludes it. It is design residue, not a Genera 8.5 feature.
• Output recording is an explicit connect and runtime option. The user guide describes scrollback but omits the keyword from its connection-option table.
• Overstrike defaults are host-sensitive. Unix and VMS family types are listed as refusing overstrike; WAITS and Multics are singled out for character insertion.
• Bury is deliberately connection-preserving. Its command waits for deexposure and later re-exposure to suppress misleading type-in/type-out notifications.

CADR source-injected shell evidence

Runtime observation: a maintained-source Supdup window injected into the isolated System 303-0 band, captured 2026-07-19. It establishes only the source-injected full-screen surface, who-line relationship, and disconnected label. It is not a pristine base-band application claim. Underlying software and display material remain the property of their respective rightsholders; reproduced for criticism, scholarship, and historical documentation under 17 U.S.C. section 107. No affiliation or endorsement is implied.

Runtime observation: an explicitly constructed maintained-source Telnet shell in the same session. Its process slots were deliberately NIL after ordinary TELNET-SEPARATE exposed a source/band initialization mismatch. It proves the distinct label and shared static window structure only, not process or connection behavior. Underlying software and display material remain the property of their respective rightsholders; reproduced for criticism, scholarship, and historical documentation under 17 U.S.C. section 107. No affiliation or endorsement is implied.

Exact image identities, run provenance, and the reconstructed ordered input sequence are in the curated CADR asset catalog. Publication is limited by the D10 capture-specific rights review.

The fresh run first proved that live System Help contains no S/T registration. The base band reported older compiled definitions from SYS: WINDOW; SUPDUP, while the pinned maintained file had to be loaded through the private FILE bridge and accepted redefinitions. The resulting Supdup type-in process encountered the isolated absent- peer/path boundary. Ordinary maintained-source Telnet creation then encountered an unbound process slot, which is why the second image is explicitly a static shell witness. The run stopped cleanly with the base disk unchanged. There is no configured System 46 band, so its runtime appearance remains a named blocker.

Genera disconnected state

Runtime observation: Genera 8.5/System 452.22 immediately after local login and Select T, captured 2026-07-19. It establishes the exact prompt, initial label, scrollbar, blank surface, who-line, and relative geometry only. Underlying Symbolics software and display material remain the property of their respective rightsholders; reproduced for criticism, scholarship, and historical documentation under 17 U.S.C. section 107. No affiliation or endorsement is implied.

The live prompt contradicts the manual's nearby wording, and the rendered label is exactly Terminal 1. The pixels cannot reveal the hidden label tag or establish when source-profile label recomputation occurred; that relationship remains an oracle. The capture contains no Help/manual prose, source, peer data, artwork, or private content. A later raw Network-Help capture remains ignored. Exact provenance is in the curated Genera asset catalog, under the same D10 rights decision.

What still requires deterministic isolated peers

The following remain explicit oracles:

• successful native Chaos SUPDUP and gateway Telnet connection establishment;
• Telnet first-IAC and steady-state negotiation, binary and echo transitions;
• SUPDUP terminal-variable exchange and every display/graphics effector;
• interrupt, logout, More, literal escape, wallpaper and disconnect behavior while connected;
• protocol-specific history limits and simulator output;
• send/receive file behavior using disposable project-owned data; and
• exact source-to-compiled-world identity for both tested bands.

Each peer must live inside the throwaway namespace, expose no external route, real credentials, or uncontrolled login service, and record both byte directions. It must not pretend that a protocol test fixture is an historical ITS, TOPS-20, Unix, VMS, or Symbolics site.