Metal Black (Arcade)

Metal Black
Also known as: Gun Frontier 2 (Intro & Credits) Developer: Taito Publisher: Taito Platform: Arcade (Taito F2 System) Released internationally: September 1991 This game has unused code. This game has unused graphics. This game has debugging material. This game has a hidden level select. This game has regional differences.

Metal Black is the supposed sequel to Gun & Frontier, even though the only thing the two games have in common is that they're both shoot 'em ups. The gimmick in this one is that the player has to collect molecules called "Newalone"; these molecules both upgrade the player's main weapon and are used as an energy source for a much more powerful beam attack that empties the meter. Unfortunately for the player, bosses can collect Newalone too...

Stage Select

This game uses the Taito Code:

• While the game boots up, hold the Service Coin button until a "SERVICE SWITCH ERROR" message pops up on the screen.
• The next step depends on the Cabinet dip switch.

• If set to "4 Players / 4 Coin Slots", press 1P Button 1 (x3), Service Coin, 1P Button 1.
• Otherwise, press 1P Start (x3), Service Coin, 1P Start.

Press 1P Up/Down to select the round, then press 1P Button 1 to start a new game. There's no way to change the area number, but the game doesn't actually use this value anyway so it doesn't matter.

Debug Functions

Put the following code in metalb.xml to change the Press Start screen to one of six debugging functions:

  <cheat desc="Debug Functions">
    <parameter>
      <item value="0x7B50">BG Transformation Test</item>
      <item value="0x96CE">Collision Viewer</item>
      <item value="0xAB42">Camera Debug</item>
      <item value="0xAFBC">Zoom Test</item>
      <item value="0xB5FA">Chunk Viewer</item>
      <item value="0xB6C4">Sprite Viewer</item>
    </parameter>
    <script state="run">
      <action>maincpu.md@1BD88=4EB90005</action>
      <action>maincpu.mw@1BD8C=param</action>
    </script>
    <script state="off">
      <action>maincpu.md@1BD88=41FA14EE</action>
      <action>maincpu.mw@1BD8C=082D</action>
    </script>
  </cheat>

BG Transformation Test

A simple test of the different background transformation effects. Makes a decent screensaver. Switch between two different backgrounds, the second one having being overwritten with the final boss background graphics at some point.

Press 1P Button 1 to cycle through different transformation effects.

Collision Viewer

Displays the game's foreground chunks both with and without visible collision. The player can add and delete collision here but there doesn't seem to be a way to save it, and this tool never tries to write to ROM at any point.

Controls

• 1P Joystick: Moves cursor.
• 1P Button 1: Marks tile as solid.
• 1P Button 2: Erases tile collision.
• 2P Up/Down: Moves "CODE" cursor.
• 2P Left/Right: Adjusts "CODE" value (Doesn't seem to do anything).
• 2P Button 1 / Button 2: Goes to the next / previous chunk.

Camera Debug

Should probably be a camera debugging tool but it doesn't seem to work.

Controls

• 1P Up/Down: Moves cursor.
• 1P Left/Right: Adjust parameter by 1 per tap.
• 1P Button 1 / Button 2: Adjusts value by 10 per tap.

Zoom Test

Tests the zooming capabilities of the Taito F2 System.

Controls

• 1P Up/Down: Moves cursor.
• 1P Left/Right: Adjust parameter by 1 per tap.
• 1P Button 1 / Button 2: Adjusts value by 10 per tap.
• 2P Left/Right: Adjusts parameter by 1 per frame when held.
• 2P Button 1: Decreases H ZOM by 2 and V ZOM by 1 every frame when held.
• 2P Button 2: Increase H ZOM by 2 and V ZOM by 1 every frame when held.

Chunk Viewer

A rougher version of the collision viewer that includes all of the game's 128x128 chunks, not just the foreground. It's a bit unwieldy.

Controls

• 1P Button 1: Loads next chunk once per tap.
• 1P Button 2: Loads next chunk once per frame.
• 2P Button 1: Resets to the first chunk.
• 2P Button 2: Makes current chunk invisible.

Sprite Viewer

A sprite viewer that also doubles as an ersatz canvas art program.

Controls

• 1P Up/Down: Adjusts vertical position.
• 1P Left/Right: Adjusts horizontal position.
• 1P Button 1 / Button 2: Increases / decreases current sprite ID.
• 1P Button 2 + Button 2: Increases current sprite ID by 10.
• 2P Up/Down: Increases / decreases value priority value, which ranges from 00 to 02 in descending priority.
• 2P Button 1: Pastes sprite to the screen.
• 2P Start: Clears screen.

(Sprite Viewer: ねこ自慢ブログ (升) Wayder Cheat 0.169)

(Other debug functions: Original TCRF research)

Unused Graphics

Graphics for more traditional power-up items, they're listed as D18ITM1 to D18ITM7 in the sprite viewer.

(Source: Original TCRF research)

High Score Names

There are seven special high score names. The first is a Taito standard: The player can't enter the name SEX, which is overwritten by ヒミツ (Secret) in the Japanese version and *** in all other versions.

The other six names can only be entered in the Japanese version. Entering any of these briefly displays a message in red in place of the name, but does not overwrite the name in the high score table.

Name	Message
TEN	HA!
YAC	♪♬♪
M.B	メタルブラック
AGA	アガジオ
UME	AMAIYO!
WEP

Three of the names have additional effects:

• UME plays three klaxon sounds after it's entered.

• TEN spawns five of those energy-eating snakes from the Stage 2 boss to chase the sunfish off.

• AGA makes the sunfish turn towards the player.

(Source: Original TCRF research)

Error Handler Leftovers

Most of the standard 68000 exception vectors have entries in the exception vector table, but they all point to ROM space 0x0F00000. That ROM space might have been used by development hardware while the game was still being tested, but it's empty in the final game. This is identical to the dummied-out handlers in Battle Shark and Gun & Frontier.

Vector	Address
Bus Error	0xF00000
Address Error	0xF00014
Illegal Instruction	0xF00028
Zero Divide	0xF0003C
CHK Instruction	0xF00050
TRAPV Instruction	0xF00064
Privilege Violation	0xF00078
Trace	0xF0008C
Line 1010 Emulator	0xF0009A
Line 1111 Emulator	0xF0009A

(Source: Original TCRF research)