Junk Yard

Identity and evidence precedence

Junk Yard is a Williams WPC-95 machine (manual 16-50052-101, JANUARY 1997 FINAL). Pinned PinMAME's own libpinmame.h names the GEN_WPC95 constant "Integrated boards, Congo 3/96 - Cactus Canyon 2/99", i.e. Junk Yard is part of the same integrated-board WPC-95 hardware generation as the other machines in that era. The retained known-working table (VPX v1.3, author mfuegemann; primitives/textures by Fuzzel and Dark, lighting by Hauntfreaks) binds driver jy_12, the production 1.2 ROM (DCS sound).

This curation follows the project's standard evidence-authority order: the retained script is runtime/causality ground truth, the Williams manual is physical-construction/wiring/quantity ground truth, pinned PinMAME source is controller-topology ground truth, and the retained table supplies geometry. The retained manual (146 pages) carries a usable OCR text layer, but every printed table cited here was read from 200 dpi renders and transcribed by a vision-capable model worker into evidence/excerpts/williams.junkyard.1996/, cross-checked across the repeated copies (front matter, printed 2-38, and Section 3). These transcriptions are recorded with reviewed: false / method: model — a vision-capable curator has not yet visually re-checked them against the rendered pages. The polarity, spatial, controller-topology, and mechanism-causality conclusions rest on pinned PinMAME source, the retained VPX geometry/script, and the cross-copy comparison rather than on the unchecked transcription alone, and the semantic device identities are corroborated by the retained VPX object names and the pinned PinMAME source. The raw transcription wording (labels, part-number spellings) remains subject to a curator re-check of the excerpt transcriptions before author-ready promotion. A retained 16-page operator handbook (born-digital, with a real text layer) reproduces the same tables and can assist that re-check.

Junk Yard has no pop bumpers. Unlike most WPC-95 machines, neither the switch matrix nor the solenoid table lists a jet/popper bumper; the playfield features standup targets, slingshots, a crane with a wrecking ball, a refrigerator popper, a fork-lift scoop, a dog-house mechanism, and a spinner.

Controller platform and address topology

Reuses controllers/pinmame/wpc-95.json unchanged, confirmed directly from jyGameData's own GEN_WPC95 field in src/wpc/sims/wpc/prelim/jy.c. The switch matrix, Fliptronic column, LPDC duplication (37-40 mirrored at 41-44), and five-string GI layout all follow the standard WPC-95 rules already documented on that profile.

Junk Yard declares no custom switch column, no auxiliary lamp column, and no custom solenoid board (jyGameData's trailing hw fields are all zero), so this is a clean WPC-95 baseline with no address-remapping surprises beyond the flipper circuits below. The switch matrix's eighth column (81-88) is entirely unpopulated; switches 23, 25, 55, and 75 are also printed Not Used.

Flipper circuits. Printed circuits 29/30 (Lwr Rt Power/Hold) and 31/32 (Lwr Lt Power/Hold) map to public addresses 45-48 (CORE_FIRSTLFLIPSOL=45). Printed circuits 33-36 (the "Upr. Rt."/"Upr. Lt." driver-board slot, CORE_FIRSTUFLIPSOL=33) already equal their own public addresses. Junk Yard fits no upper flippers: jyGameData declares FLIP_SOL(FLIP_L) only, so no upper flipper solenoid is CPU-driven and no upper FLIP_EOS bit is set. The Switch Locations page marks F6 (Upper Right Flipper Cabinet), F7 (Upper Left Flipper E.O.S.) and F8 (Upper Left Flipper Cabinet) Not Used.

The flipper-column switch treatment deserves precision because it depends on PinMAME's flipMask construction (core.c:2510-2517), which is driven by jyGameData's FLIP_SW(FLIP_L | FLIP_U) | FLIP_SOL(FLIP_L). That mask always carries the lower-right/left button bits and the lower EOS bits (from FLIP_SOL(FLIP_L)), and additionally the upper-right/left button bits (from FLIP_SW(FLIP_U)); it carries no upper EOS bit. The two addresses that PinMAME genuinely forces every VBLANK regardless of keyboard mode are the lower end-of-stroke contacts 111 and 113: core_updateSw recomputes them from core_getSol (the flipper hold-coil state) plus CORE_FLIPSTROKETIME (core.c:1756-1775) and writes them back, so a recreation must not drive 111 or 113. The button addresses 112/114/116/118 are read from and written back to the matrix unchanged when keyboard handling is off (core.c:1731, the LibPinMAME default g_fHandleKeyboard=0), so the emulator publishes no meaningful runtime state at them; 116/118 are additionally unfitted (no physical upper-flipper button exists) and are recorded unused, while 117 (upper-left EOS) is dead because no upper FLIP_EOS bit is set. F5, however, is not a flipper contact at all: the manual prints it "SPINNER" (part 5647-12693-24), and the retained script's Switch115_Spin handler pulses it as the playfield spinner. This is the same "Fliptronic F5 repurposed for a non-flipper device" pattern Monster Bash established with its Center Spinner.

Opto polarity sweep

The manual's Switch Locations parts list (2-35) identifies eleven opto-constructed switches by printing an LED/photo-transistor pair on two lines rather than a single mechanical part: 31-35 (A-18617-1/A-18618-1, the trough) and 36-37 (lock-up) and 41-44 (Past Spinner, In The Sewer, Lock Jam, Past Crane) (all A-16908/A-16909). The switch matrix (2-34) shades column 3 rows 1-7 as "OPTO, TYPICALLY CLOSED".

Pinned PinMAME's jyGameData inverted-switch mask ({0x00,0x00,0x00,0x7f,0x07,0x00,...}) normalizes column 3 rows 1-7 (31-37) and column 4 rows 1-3 (41-43). That matches the manual on ten of the eleven opto addresses. The single disagreement is switch 44 (Past Crane): opto-constructed per the manual but not normalized by PinMAME (column 4 row 4 is outside the mask's 0x07). This is the same family of conflict as Monster Bash's Dracula-position optos and Indiana Jones's captive-ball opto, and is recorded as conflict.junkyard.past-crane-opto-not-normalized.

Mechanisms

• Four-ball trough and release (A-19963-1): the retained script's cvpmBallStack helper bsTrough reads switches 32-35 as a plain switch array and ejects the ball through solenoid 9, pulsing opto 31 in the same SolTrough event.
• Shooter lane and auto plunger (A-21022): the Autoplunger handler pulls back and fires Auto_Plunger only when switch 18 is active.
• Crane with wrecking ball (A-21523): solenoid 3 (Power Crane) drives the arm, solenoid 15 (Hold Crane) holds it; switches 15 (Top Left Crane), 38 (Top Right Crane), 44 (Past Crane), and 28 (Crane Down) report the head's positional limits.
• Refrigerator popper (A-21216): bsFridgePopper uses switch 37 as the entry and switches 36/43 as the internal ball-stack array; solenoid 2 ejects.
• Bus ramp diverter (A-21409-1): solenoid 6 rotates a diverter flap (Sol6.IsDropped) with no dedicated switch.
• Spike the dog (A-21383): solenoid 16 drives the dog-house spike arm; SpikeBark/SpikeTimer animate it while switch 74 reports a ball in the dog-house entry.
• Fork-lift scoop (A-21220): solenoid 5 (Scoop Down) and solenoid 21 (Scoop Up) lower/raise the fork arms; switches 73 (Scoop Made) and 72 (state) report the scoop.
• Car targets (SW-1A-210): five standup targets at the top of the playfield (46-48, 53-54); there is no resettable drop mechanism.
• Three-bank target clusters (A-21349-1 / A-21351): four clusters of three standup targets (56-58, 61-63, 64-66, 76-78); no bank is solenoid-reset.
• Slingshots (B-9362-R-3): left (solenoid 10, switch 51) and right (solenoid 11, switch 52).
• Spinner: Fliptronic F5 (public 115).

Service and setup

The front-matter DIP Switch Chart documents five country combinations (America, European, French, German, Spain) across SW1-SW8. The machine uses four balls. The crane mechanism and the wrecking ball are the headline features, with the cars, refrigerator, dog-house, and fork-lift scoop forming the themed toy complex.

Unresolved

The past-crane opto polarity conflict (switch 44) is the one open polarity question; a LibPinMAME gameplay-harness trace of the public idle state of switch 44 on a legal jy_11/jy_12 ROM is the concrete resolution path. Several crane/trough/sewer mechanism-internal sensors are documented projections onto the mechanism's real kicker rather than surveyed coordinates.

Sources

• Williams Junk Yard Operations Manual (16-50052-101, January 1997 FINAL), 146 pages, SHA-256 08819a08990c61070c4a3a99a4d5f00d9d082b6d00477ffaf9b0a58fddce3fe1.
• Retained known-working table Junk Yard (Williams 1996).vpx v1.3 by mfuegemann, SHA-256 8ff2c1c8ae3457a4b88ff2207bc506d07435b049343301ded4dbf8e855bef07f.
• Pinned PinMAME 8371478a7640f1896dcdf565aed340dc5df989ba, src/wpc/sims/wpc/prelim/jy.c.