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Namco System 21 "Polygonizer"

The first arcade hardware dedicated to polygonal 3D (Namco, 1988) — even before the Sega Model 1. A 4-board crate with dual 68000 and several TMS320 DSPs computing untextured polygons (flat/Gouraud). Winning Run, Starblade, Galaxian³… Namco led 3D until the Model 1 (1992).

PCB Namco System 21

PCB Namco System 21 — photo by Baz1521, CC BY-SA 3.0 (Wikimedia Commons).

Identification

Field Value
Manufacturer Namco
Year 1988 (Winning Run)
Type untextured polygonal 3D (multi-board crate)
Structure 4 PCBs: CPU + DSP board + 3D polygon board + object framebuffer

Architecture

Block Chip Clock Role
CPU ×2 Motorola 68000 12.288 MHz game + coordination
DSP 4× TI TMS320C25 (5× TMS320C20 on Star Blade) ~24.576 MHz 3D geometry (transform/projection)
Video 3D polygon board + object framebuffer flat/Gouraud, untextured polygon rendering
Sound Namco customs (per game) music + SFX

The flat-shaded, untextured look is the System 21's signature (like Sega's later Model 1). The power comes from the TMS320 DSP cluster offloading all the geometry. Emulated in MAME (namco/namcos21.cpp).

Notable games

Winning Run (1988), Winning Run '91, Driver's Eyes, Starblade (1991), Solvalou, Galaxian³, Air Combat, Cyber Sled (1993).

Common faults

Symptom Likely cause Lead
No 3D / freeze one of the DSP/polygon boards, interconnects Board-by-board crate diagnosis
Corrupt object image object framebuffer / RAM RAM test, contacts
Random freeze dual 68000 / shared RAM CPU diagnosis, RAM test
No sound sound customs Sound-stage diagnosis
No image Power, board interconnects Base diagnosis

A multi-board crate → methodical diagnosis; customs and DSPs are rare.

Modernisation & mods

The common ground for every JAMMA board

Video, power, control panel and upscalers depend on the cabinet rather than the board: everything is centralised in Modernising a cabinet. To run the board outside a cabinet (at home, on a display): supergun.

  • Storage 🟡: the game lives in EPROM/mask ROM on the board. Changing or restoring a game means reprogramming the EPROMs (and, for a mask ROM, using a pinout adapter) → EPROM method.
  • Media preservation: replacing the original storage, multicarts, ODEs and modern options by family → PCB preservation hub.
  • Scan rate 📺: ~31.5 kHz / 60.0 Hz — high resolution (VGA class), ⚠️ a 31 kHz / tri-sync monitor is required; a 15 kHz chassis is incompatible → tri-sync and upscalers. (Computed from the MAME sources — namco/namcos21.cpp — pixel clock ÷ htotal.)
  • FPGA / emulation: see the Emulation & FPGA section below.

Repair (technician)

  • 4 PCBs (CPU + DSP + 3D polygon + object framebuffer): diagnose board by board; DSP/3D customs are rare (donor). Corrupt 3D = test RAM + buffers first.
  • Dual 68000: a freeze = one CPU / its RAM → separate diagnosis.
  • Sound: Namco customs — diagnose the sound stage.
  • Capacitors: recap (old multi-PCB). Oxidised EPROM sockets: turned-pin socket.

→ Methods: PCB fault-finding · Recap · EPROM · Traces & vias

Expected clocks — measurement table ✅

Values extracted from the MAME sources for this platform. On a scope or frequency counter, a clock that is missing or off-value points straight at the crystal, the divider or the chip at fault — the fastest starting point on a dead board.

Component Expected clock Role
M68000 12.288 MHz main CPU
YM2151 3.579545 MHz FM (sound)

How to read this table

Several values for one component = several board variants in this family (or several instances of the chip clocked differently). These frequencies are those of the clock signal at the component's input, not of its original crystal — on many boards the clock is divided down from a single master crystal.

Original manuals for games on this platform ✅

Manufacturer manuals for games running on this board. Beyond the instructions, they very often carry the full DIP settings, the connector pinout, the test procedure, the parts list and the expected voltages.

→ Full catalogue: service manuals, wiring & game manuals

DIP settings ✅

2 games on this platform, settings extracted from the MAME sources (INPUT_PORTS_START blocks). The Position column gives the switch's physical reference on the board (SW2:!3,!4 = bank SW2, levers 3 and 4) — which is what lets you set it up without the paper manual. Games are sorted by MAME set name.

DIP settings — MAME set winrun
Setting Position Options (default in bold)
DSW2 — Off · On
DSW3 — Off · On
DSW4 — Off · On
DSW5 — Off · On
PCM ROM — 2M · 4M
DSW7 — Off · On
Screen Stop — Off · On
DIP settings — MAME set winrungp
Setting Position Options (default in bold)
PCM ROM — 2M · 4M

Check against your own board

These settings apply to the game and revision described by MAME. One title may have several DIP sets depending on region or revision, and some systems use soft-dips (settings in memory, via the test menu) rather than physical switches. In case of a discrepancy, the board's silkscreen and the test menu are authoritative.

See also: DIP reference · game manuals

Emulation & FPGA

  • Emulation: MAME (namco/namcos21.cpp) — 68000 + TMS320 reverse-engineered.
  • FPGA / MiSTer: no core (a multi-DSP 3D crate, out of budget).

EPROM repair

68000 ×2 + polygonizer DSP. Ex. (MAME namco/namcos21.cpp): Winning Run = 2× 27C010. Program in 27C010/020; 3D data in mask ROM. Starblade, Solvalou, Cyber Sled.

Lineage

After the System 2, Namco's first 3D — before the textured 3D of the System 22 (Ridge Racer, 1993). A direct rival to the Sega Model 1.

Photos / assets

(To add: System 21 crate, DSP board, polygon board, framebuffer.)

Sources & attribution

Review & corrections

How this space is used

Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.

Reading is open to everyone; posting requires signing in with Discord. Reports from the wiki's declared reviewers are handled first; anyone else's are read too, but go through a human before anything is changed.