Original Arcade ROMs Explained: Program ROMs, Graphics ROMs, and Sound ROMs

By HighScoreSaves Technical Team

Reviewed and updated August 22, 2026

Original classic arcade PCBs commonly use multiple ROM devices to store the information needed to run the game. Depending on the hardware design, separate ROMs may contain program code, graphics data, sound data, character information, lookup tables, or other game-specific content.

Understanding the difference between these ROMs is especially useful when identifying an original PCB, comparing board revisions, troubleshooting a modified board, reading an installation guide, or installing an upgrade that includes ROM Saver functionality.

This article explains what ROM means, how ROM differs from RAM, what program, graphics, and sound ROMs generally do, how EPROMs and mask ROMs fit into classic arcade hardware, and why ROM position and version can matter when working with an original arcade PCB.

What Does ROM Mean?

ROM stands for Read-Only Memory.

In an arcade game, ROM contains data that must remain available even after the machine has been powered off. Unlike ordinary volatile RAM, ROM does not lose its stored game data simply because cabinet power is removed.

The exact technology used can vary. Classic arcade boards may contain factory-programmed ROM devices, programmable ROMs, EPROMs, PROMs, or other memory devices depending on the manufacturer, game, production period, and purpose of the chip.

In everyday arcade terminology, owners and technicians often use the word "ROM" broadly when referring to chips containing the game's permanent program or data.

ROM Is Not the Same as RAM

ROM and RAM perform different jobs.

ROM normally contains information that needs to be available whenever the game starts. RAM provides temporary working memory used while the game is operating.

The CPU can use RAM for changing information such as current game state, object positions, counters, temporary calculations, and other active data.

On many original arcade systems, ordinary RAM loses its contents when power is removed. That is one reason original arcade games do not all preserve their complete high-score tables after shutdown.

HighScoreSaves kits that provide persistent score storage use separate nonvolatile storage for supported score and settings data. To understand that process, see How Arcade High Scores Are Saved Without a Battery: Serial EEPROM Explained .

What Is a Program ROM?

Program ROMs contain instructions used by the game's processor.

When the arcade PCB starts, the CPU executes program code stored in the appropriate ROM area. That code determines how the game operates: player movement, enemy behavior, scoring rules, timing, game states, input handling, collision logic, attract mode, and many other functions.

A classic arcade board may use one program ROM or several program ROMs. How they are arranged depends on the processor, memory map, board architecture, ROM capacity, and game design.

Two ROM chips that look physically similar are not necessarily interchangeable. Their data, board location, address range, and expected device type can all be different.

Why Can a Game Have Several Program ROMs?

Early memory devices stored much less information than modern storage devices. A complete arcade program therefore might be divided across several physical ROM chips.

Each device occupies a particular part of the CPU's memory map. Together, the ROMs provide the program information required by the game.

This is one reason ROM location matters. Moving the correct ROM to an incorrect socket can prevent the game from operating even if the device itself is undamaged.

What Is a Graphics ROM?

Graphics ROMs contain visual data used by the arcade hardware.

Depending on the game's architecture, stored graphics data may represent:

Characters
Sprites
Tiles
Background elements
Objects
Fonts
Animation frames
Other visual patterns

Graphics hardware reads this stored information and uses it to generate the imagery shown on the arcade monitor.

The exact process varies substantially between hardware platforms. Some boards have simple character-generation circuitry, while others use separate video processors, sprite hardware, multiple graphics memory areas, or additional board sections.

What Is a Sound ROM?

Sound-related ROMs contain data used by the audio portion of the arcade system.

Depending on the game, a sound ROM may contain sound program code, sample data, speech data, music-related information, or other information needed by dedicated sound hardware.

Some arcade games use a separate sound CPU with its own program ROMs. Others use different audio architectures.

Because hardware designs vary widely, the term "sound ROM" should be understood as a functional description rather than a guarantee that every arcade PCB contains one particular type of dedicated chip.

Are Program, Graphics, and Sound ROMs Always Separate?

No.

The categories are useful for understanding how arcade hardware works, but actual PCB architecture varies by manufacturer and game.

One board may contain clearly separated CPU program, graphics, and sound ROM areas. Another may organize its data differently or use multiple boards with different functions distributed between them.

Always identify chips by the actual PCB documentation, board markings, ROM set information, or installation guide rather than by appearance alone.

What Is an EPROM?

EPROM stands for Erasable Programmable Read-Only Memory.

EPROMs were widely useful because their contents could be programmed after the chip was manufactured. Traditional ultraviolet-erasable EPROMs can often be recognized by a small transparent quartz window on top of the package.

That window allowed ultraviolet light to erase the stored data so the device could be programmed again.

Arcade operators, manufacturers, repair technicians, and later collectors may encounter EPROMs containing factory revisions, replacement code, regional versions, conversions, repairs, or modified software.

What Is a Mask ROM?

A mask ROM is programmed as part of the manufacturing process rather than being individually programmed later like a typical EPROM.

Manufacturers could use mask ROMs for production once game code or data was finalized.

From the perspective of someone identifying an arcade PCB today, the important point is that an original board may contain different ROM technologies while all of them perform nonvolatile data-storage roles.

Why Are ROM Labels Important?

ROM labels can contain valuable identification information.

Depending on the manufacturer and device, a label may indicate:

Game identifier
ROM position
Program revision
Regional version
Part number
Sequence or location information

A complete photograph of the ROM area can help identify whether a PCB contains the expected software or whether it has been converted, repaired, modified, or updated.

This is why HighScoreSaves recommends photographing ROM labels when exact PCB compatibility is uncertain.

See How to Identify Your Original Arcade PCB Before Ordering a Kit for a complete PCB identification photo checklist.

Does a Different ROM Version Mean It Is a Different PCB?

Not necessarily.

The same original PCB hardware may have been used with more than one software revision. Manufacturers sometimes revised game programs to correct bugs, adjust gameplay, change regional behavior, or make other updates.

At the same time, some games also have multiple PCB revisions. Therefore, the ROM version and PCB revision are two separate pieces of identification information.

Both can matter when determining upgrade compatibility.

Can a Replacement EPROM Still Be on an Original Arcade PCB?

Yes. The presence of a replaced ROM device does not by itself mean the entire arcade PCB is a reproduction or replacement board.

Original PCBs have been serviced for decades. Sockets, ROMs, CPUs, capacitors, resistors, connectors, and other components may have been replaced during normal repair work.

The larger question is the identity and architecture of the PCB itself.

For more information about distinguishing original hardware from modern alternatives, see Original Arcade PCB vs. Replacement or Emulation Board: What's the Difference? .

What Happens If a ROM Is Installed Backward?

Integrated circuits must be installed in the correct orientation.

Installing a socketed ROM backward can prevent the game from operating and may damage the device or associated hardware when power is applied.

Before removing any socketed IC, document its orientation and identify Pin 1.

HighScoreSaves has a dedicated guide explaining notches, molded dots, PCB markings, sockets, and daughterboard orientation: How to Identify Pin 1 on an Arcade CPU, ROM, Socket, and Daughterboard .

Do Not Remove ROMs Just to Identify Them

If the label can be photographed while the ROM is installed, leave it installed.

Unnecessary chip removal introduces the possibility of bent pins, damaged sockets, incorrect orientation, missed socket rows, static damage, or reinstalling a device in the wrong location.

A clear overhead photograph normally provides much of the identification information needed without disturbing the board.

What Is ROM Saver?

On supported HighScoreSaves kits, ROM Saver refers to a feature that allows specified original program ROMs to be removed from active service because the required program information is provided by the upgrade hardware.

This does not mean that every ROM on the PCB should be removed.

Graphics ROMs, sound-related ROMs, PROMs, custom devices, and other memory components may still be required by the original hardware.

Only the exact ROMs identified by the game-specific HighScoreSaves instructions should ever be removed as part of a ROM Saver installation.

Read the complete guide: What Is ROM Saver on a Classic Arcade PCB Upgrade Kit? .

How Do Multigame Kits Use ROM Data?

A multigame upgrade can provide additional program data for multiple compatible games or game versions while continuing to use the supported original arcade PCB as the hardware platform.

The exact implementation depends on the game and kit.

This is fundamentally different from replacing the original arcade board with a generic computer running software emulation.

Learn more in How Multigame Upgrade Kits Work on Original Arcade PCBs .

ROMs and DIP-Switch Settings Are Different

Program ROMs contain game instructions and permanent data. DIP switches provide configurable electrical inputs that the program can read.

Changing a DIP switch does not rewrite a program ROM.

For a detailed explanation of operator settings, see How Classic Arcade DIP Switches Work and What They Control .

ROMs and High-Score Storage Are Also Different

The presence of ROM on a PCB does not automatically mean player high scores are permanently stored.

ROM generally provides game code and fixed data. Player-created information needs a writable storage method if it is expected to survive power loss.

Supported HighScoreSaves kits use nonvolatile storage for saved score information rather than attempting to write new score data into the original game program ROMs.

Important Rules When Working Around Arcade ROMs

Disconnect cabinet power before removing or installing socketed devices.
Photograph the PCB and ROM locations before making changes.
Identify Pin 1 before removal and again before installation.
Do not identify a ROM only by package appearance.
Do not assume every ROM on a PCB is a program ROM.
Do not move ROMs between sockets unless documentation specifically requires it.
Do not remove ROMs merely because a kit supports ROM Saver.
Follow the exact game-specific installation guide.
Keep removed original ROMs labeled and stored safely.

Related HighScoreSaves Arcade Knowledge

Learn More About Original Arcade PCBs

ROMs are part of a larger hardware system that includes CPUs, RAM, custom logic, audio circuitry, video hardware, input circuitry, sockets, edge connectors, and cabinet wiring.

Understanding those components helps collectors and technicians preserve original arcade hardware while making informed decisions about repairs and upgrades.

Visit HighScoreSaves Arcade Knowledge & News for additional guides covering arcade PCB identification, installation, troubleshooting, High Score Save Kits, multigame upgrades, Wi-Fi leaderboards, and original arcade hardware.