Sega System 1 / System 2

Sega's 8-bit platform in the mid-80s: two Z80s (game + sound), tiles + sprites, and above all many encrypted games (custom Z80 / MC-8123). Flicky, Wonder Boy, Choplifter, Pitfall II… System 2 is an evolution (more sprites). A MiSTer core exists → excellent preservation.

Identification

Field	Value
Manufacturer	Sega
Years	System 1 (1983) · System 2 (1985)
Type	8-bit tile + sprite platform
Connector	Sega harness / JAMMA conversions
Settings	DIP

Architecture

Block	Chip	Clock	Role
CPU	Zilog Z80	~4 MHz	game logic (often encrypted, see below)
Sound CPU	Zilog Z80	~4 MHz	drives the sound
Sound	2× SN76489 (PSG)		+ YM2151 (FM) on later games
Video	Sega customs (tilemaps + sprites)		256×224 (often a vertical cabinet), a wide palette for 8-bit 2D

The System 2 (1985) reuses the base while increasing the sprite count and graphical richness — the same family in MAME (sega/system1.cpp).

Protection (the real topic)

Many System 1/2 games run on an encrypted Z80:

• Sega custom Z80 (315-5xxx): the opcodes are scrambled; without the (reverse-engineered) decryption table the program is unreadable.
• MC-8123: a decryption module with a battery-backed key (like some System 16) → a dead battery can "suicide" those games. The keys have been extracted by the community.

→ Per-game keys (FD1094/FD1089/MC-8123/8751): System 16 — per-game keys (the table also covers the MC-8123).

Notable games

Flicky, Wonder Boy (1986), Choplifter, Pitfall II: The Lost Caverns, Up'n Down, SWAT, Star Jacker, TeddyBoy Blues, My Hero, Mister Viking, Regulus, 4D Warriors, Water Match… (System 2 adds richer variants).

Common faults

Symptom	Likely cause	Lead
Black screen / stuck boot	MC-8123: dead key battery (encrypted games)	Re-key / decrypted ROM (see per-game keys)
Corrupt sprites/tiles	video RAM, customs	RAM test, contacts
No sound	sound Z80 / SN76489 (/ YM2151)	Sound-stage diagnosis
Lost settings	DIPs misset	Check the DIP bank
No image	Power, Z80, harness	Base diagnosis

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.

• Battery 🟢: a save battery is fitted (settings/counters/RTC). ⚠️ On this platform, a dead battery does NOT kill the game — it is a leaking battery that corrodes traces. Check and replace it before it leaks → save batteries.
• 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 📺: ~15.62 kHz / 60.1 Hz — standard resolution, a classic 15 kHz chassis is fine — the most common JAMMA case → tri-sync and upscalers. (Computed from the MAME sources — sega/system1.cpp — pixel clock ÷ htotal.)
• FPGA / emulation: see the Emulation & FPGA section below.

Repair (technician)

• Encrypted Z80 program (315-xxxx) on many games: without the correct decode chip/board it won't boot — check before suspecting the logic.
• Sega customs (tilemaps/sprites): corrupt = video RAM + buffers first, the custom next (donor).
• Sound: sound Z80 + 2× SN76489 (+ late YM2151) — diagnose the sound stage.
• Capacitors: recap PSU + audio filtering. 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
I8751	8 MHz	protection MCU
SN76489A	2 MHz · 4 MHz	PSG
Z80	4 MHz	sound CPU (usually)

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.

• Up'n Down — original manual (PDF)

→ Full catalogue: service manuals, wiring & game manuals

DIP settings ✅

40 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 4dwarrio

Setting	Position	Options (default in bold)
Lives	SWB:2,3	3 · 4 · 5 · Infinite
Bonus Life	SWB:4,5,6	30000 · 40000 · 50000 · 60000 · 70000 · 80000 · 90000 · None
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set blockgal

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:4	2 · 3
Bonus Life	SWB:5	10k 30k 60k 100k 150k · 30k 50k 100k 200k 300k
Allow Continue	SWB:6	No · Yes

DIP settings — MAME set blockgalb

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:4	2 · 3
Bonus Life	SWB:5	10k 30k 60k 100k 150k · 30k 50k 100k 200k 300k
Allow Continue	SWB:6	No · Yes

DIP settings — MAME set brain

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite

DIP settings — MAME set bullfgt

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	30000 · 50000 · 70000 · None

DIP settings — MAME set choplift

Setting	Position	Options (default in bold)
Coin A	SWA:1,2,3,4	4C 1C · 3C 1C · 2C 1C · 2 Coins/1 Credit 5/3 6/4 · 2 Coins/1 Credit 4/3 · 1C 1C · 1 Coin/1 Credit 2/3 · 1 Coin/1 Credit 4/5 · 1 Coin/1 Credit 5/6 · 2C 3C …
Coin B	SWA:5,6,7,8	4C 1C · 3C 1C · 2C 1C · 2 Coins/1 Credit 5/3 6/4 · 2 Coins/1 Credit 4/3 · 1C 1C · 1 Coin/1 Credit 2/3 · 1 Coin/1 Credit 4/5 · 1 Coin/1 Credit 5/6 · 2C 3C …
Cabinet	SWB:1	Upright · Cocktail
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	2 · 3 · 4 · Free Play
Bonus Life	SWB:5	20k 70k 120k 170k · 50k 100k 150k 200k
Difficulty	SWB:6	Hard · Easy

DIP settings — MAME set dakkochn

Setting	Position	Options (default in bold)
Coinage	SWB:1,2	1C 1C · 1C 2C · 1C 3C · 1C 4C

DIP settings — MAME set flicky

Setting	Position	Options (default in bold)
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	30000 80000 160000 · 30000 100000 200000 · 40000 120000 240000 · 40000 140000 280000
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set flickyb

Setting	Position	Options (default in bold)
Lives	SWB:3,4	1 · 2 · 3 · Infinite

DIP settings — MAME set flickys1

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	2 · 3 · 4 · 5 (Infinite)
Bonus Life	SWB:5,6	80000 · 160000 · 240000 · 320000

DIP settings — MAME set gardia

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	5k, 20k and 30k · 10k, 25k and 50k · 15k, 30k and 60k · None
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set hvymetal

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	50000 100000 · 60000 120000 · 70000 150000 · 100000
Difficulty	SWB:7	Easy · Hard
Allow Continue	SWB:8	No · Yes

DIP settings — MAME set imsorry

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	30000 · 40000 · 50000 · None

DIP settings — MAME set mrviking

Setting	Position	Options (default in bold)
Maximum Credits	SWB:2	9 · 99
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	10k, 30k then every 30k · 20k, 40k then every 30k · 30k, then every 30k · 40k, then every 30k
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set mrvikingj

Setting	Position	Options (default in bold)
Difficulty	SWB:8	Easy · Hard

DIP settings — MAME set myhero

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	30000 · 50000 · 70000 · 90000
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set nob

Setting	Position	Options (default in bold)
Coin A	SWA:1,2	2C 1C · 1C 1C · 1C 2C · 1C 3C
Coin B	SWA:3,4	2C 1C · 1C 1C · 1C 2C · 1C 3C
Difficulty	SWA:5,6	Easy · Medium · Hard · Hardest
Cabinet	SWA:7	Upright · Cocktail
Flip Screen	SWA:8	Off · On
Lives	SWB:1,2	2 · 3 · 5 · 99
Bonus Life	SWB:3,4	40k, 80k, 120k and 160k · 50k, 100k and 150k · 60k, 120k and 180k · None
Allow Continue	SWB:5	No · Yes
Free Play	SWB:6	Off · On

DIP settings — MAME set pitfall2

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5	20000 50000 · 30000 70000
Allow Continue	SWB:6	No · Yes
Time	SWB:7	2 Minutes · 3 Minutes

DIP settings — MAME set pitfall2u

Setting	Position	Options (default in bold)
Lives	SWB:2,3	3 · 4 · 5 · Infinite
Starting Stage	SWB:4,5	1 · 2 · 3 · 4

DIP settings — MAME set raflesia

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	20k, 70k and 120k · 30k, 80k and 150k · 50k, 100k and 200k · None

DIP settings — MAME set regulus

Setting	Position	Options (default in bold)
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Difficulty	SWB:7	Easy · Hard
Allow Continue	SWB:8	No · Yes

DIP settings — MAME set seganinj

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	2 · 3 · 4 · 240
Bonus Life	SWB:5	20k 70k 120k 170k · 50k 100k 150k 200k
Allow Continue	SWB:6	No · Yes
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set shtngmst

Setting	Position	Options (default in bold)
Shots Per Second	SWB:1	3 · 5
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Infinite
Bonus Life	SWB:5,6	100k, 500k · 150k, 600k · 200k, 700k · 300k, 800k
Difficulty	SWB:7,8	Easy · Medium · Hard · Hardest

DIP settings — MAME set spatter

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	2 · 3 · 4 · Infinite
Bonus Life	SWB:5,6	40k, 120k and 480k · 50k and 200k · 100k only · None
Reset Timer/Objects On Life Loss	SWB:7	No · Yes

DIP settings — MAME set starjack

Setting	Position	Options (default in bold)
Lives	SWB:2,3	3 · 4 · 5 · Infinite
DEF STR (Bonus Life	SWB:4,5,6	Every 20k · Every 30k · Every 40k · Every 50k · 20k, then every 30k · 30k, then every 40k · 40k, then every 50k · 50k, then every 60k
Difficulty	SWB:7,8	Easy · Medium · Hard · Hardest

DIP settings — MAME set starjacks

Setting	Position	Options (default in bold)
Ship	SWB:4	Single · Multi
Bonus Life	SWB:5,6	30k, then every 40k · 40k, then every 50k · 50k, then every 60k · 60k, then every 70k

DIP settings — MAME set swat

Setting	Position	Options (default in bold)
Lives	SWB:2,3	3 · 4 · 5 · Infinite
Bonus Life	SWB:4,5,6	30000 · 40000 · 50000 · 60000 · 70000 · 80000 · 90000 · None

DIP settings — MAME set system1_generic

Setting	Position	Options (default in bold)
Coin A	SWA:1,2,3,4	4C 1C · 3C 1C · 2C 1C · 2 Coins/1 Credit 5/3 6/4 · 2 Coins/1 Credit 4/3 · 1C 1C · 1 Coin/1 Credit 2/3 · 1 Coin/1 Credit 4/5 · 1 Coin/1 Credit 5/6 · 2C 3C …
Coin B	SWA:5,6,7,8	4C 1C · 3C 1C · 2C 1C · 2 Coins/1 Credit 5/3 6/4 · 2 Coins/1 Credit 4/3 · 1C 1C · 1 Coin/1 Credit 2/3 · 1 Coin/1 Credit 4/5 · 1 Coin/1 Credit 5/6 · 2C 3C …
Cabinet	SWB:1	Upright · Cocktail
SW 0 Read From	SWB:8	Port $0D · Port $10

DIP settings — MAME set teddybb

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	2 · 3 · 4 · 252
Bonus Life	SWB:5,6	100k 400k · 200k 600k · 400k 800k · 600k
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set tokisens

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	1 · 2 · 3 · 4

DIP settings — MAME set tokisensa

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On

DIP settings — MAME set ufosensi

Setting	Position	Options (default in bold)
Difficulty	SWB:1,2	Easy · Normal · Hard · Hardest
Lives	SWB:3,4	3 · 4 · 5
Cabinet	SWB:5	Upright · Cocktail
Allow Continue	SWB:6	No · Yes
Demo Sounds	SWB:7	Off · On
Invulnerability	SWB:8	Off · On

DIP settings — MAME set upndown

Setting	Position	Options (default in bold)
Lives	SWB:2,3	3 · 4 · 5 · Infinite
Bonus Life	SWB:4,5,6	10000 · 20000 · 30000 · 40000 · 50000 · 60000 · 70000 · None
Difficulty	SWB:7,8	Easy · Medium · Hard · Hardest

DIP settings — MAME set wbdeluxe

Setting	Position	Options (default in bold)
Energy Consumption	SWB:8	Slow · Fast

DIP settings — MAME set wbml

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Free Play
Bonus Life	SWB:5	30000 100000 200000 · 50000 150000 250000
Difficulty	SWB:6	Easy · Hard
Test Mode	SWB:7	Off · On

DIP settings — MAME set wboy

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Lives	SWB:3,4	3 · 4 · 5 · Free Play
Bonus Life	SWB:5	30k 100k 170k 240k · 30k 120k 210k 300k
Allow Continue	SWB:6	No · Yes
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set wboy3

Setting	Position	Options (default in bold)
Lives	SWB:3,4	1 · 2 · 3 · Free Play

DIP settings — MAME set wboysys2

Setting	Position	Options (default in bold)
Lives	SWB:3,4	3 · 4 · 5 · Free Play
Bonus Life	SWB:5	30k 100k 170k 240k · 30k 120k 210k 300k
Allow Continue	SWB:6	No · Yes
Difficulty	SWB:7	Easy · Hard

DIP settings — MAME set wboyu

Setting	Position	Options (default in bold)
Cabinet	SWB:1	Upright · Cocktail
Lives	SWB:2,3	2 · 3 · 4 · 5
Demo Sounds	SWB:7	Off · On
Coinage	SWA:1,2,3	4C 1C · 3C 1C · 4C 2C · 2C 1C · 3C 2C · 2C 2C · 1C 1C · 1C 2C
Allow Continue	SWA:5	No · Yes
Mode	SWA:7,8	Normal Game · Free Play · Test Mode · Endless Game

DIP settings — MAME set wmatch

Setting	Position	Options (default in bold)
Demo Sounds	SWB:2	Off · On
Time	SWB:3,4	Normal · Fast · Faster · Fastest
Difficulty	SWB:7	Easy · Hard

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 (sega/system1.cpp) — Z80/MC-8123 decryption included.
• FPGA / MiSTer: a Sega System 1 core is available (MrX-8B / Blackwine implementation) — a hardware rebuild of the board.

EPROM repair

Z80 program in 8-32 KB ROMs: 2764 (8K) · 27128 (16K) · 27C256 (32K) depending on the game's age (e.g. Choplifter/Shooting Master/WBML/UFO Senshi = 3× 27C256; Flicky/Wonder Boy = small ROMs). ⚠ Many System 1 use an encrypted Z80 (317-xxxx): the program is encrypted, you need the decrypted ROMs (MAME dumps) for a bare-Z80 board.

Lineage

Precedes the System 16 (16-bit, 68000). See also the System E (Master System hardware) and the Super Scaler (sprite-scaling pseudo-3D) of the same period.

Photos / assets

(To add: System 1/2 board, custom Z80, MC-8123.)

Sources & attribution

• MAME — sega/system1.cpp (2× Z80, SN76489/YM2151, sprites, Z80/MC-8123 encryption, games) — https://github.com/mamedev/mame
• MiSTer — MiSTer-Arcade-SEGASYS1 (MrX-8B) — https://github.com/MrX-8B/MiSTer-Arcade-SEGASYS1
• Wikipedia — Sega System 1 — CC-BY-SA — https://en.wikipedia.org/wiki/Sega_System_1

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.