MPU Battery Replacement Options

1 Introduction

RAM chips are typically used to store game settings and bookeeping data. However, RAM is volatile and can only store data if power is applied to the chip. If power is lost, so is the data. So, the solution to this was to include a battery on the MPU to retain the data in RAM when the game was turned off.

Unfortunately, many of these batteries leak and damage or destroy circuit boards in the process. So, it is imperative that the battery is removed from the MPU in order to prevent this damage in the future.

In order to retain the data for game settings and bookeeping, there are a few different options to replace the original battery and prevent future problems from leakage.

1.1 Remote Battery

The remote battery solution is when

1.2 Lithium Battery

Classic Williams games had a build-in battery holder that could fit AA batteries. Unfortunately, it was common to see standard alkaline batteries used in these holders, which always leaked.

Lithium batteries are produced in the AA battery footprint, so can be installed in the battery holders used on classic Williams MPUs. Lithium batteries are less prone to leaking, but it is still a good idea to mount them off the MPU in a remote battery pack.

Installing batteries directly onto the MPU leaves the game open to the possibility of an owner replacing a dead AA lithium battery with a AA alkaline battery if they don't have a lithium battery on-hand because it's the easy and lazy thing to do. As a result, battery leakage becomes a serious risk again.

1.3 Memory Capacitor

Memory capacitors are special capacitors that hold a charge for an extended period of time and take the place of a battery. The downside is that the game has to be turned on at least once for several hours every 14-30 days in order to build up to a full charge.

Additionally, lower quality capacitors are prone to leaking, though not as spectacularly as alkaline or NiCad batteries.

At this point, memory capacitors have fallen from favor because of the introduction and economical prices of lithium batteries, coin cell batteries, and NVRAM.

1.4 Coin Cell / Button Battery

Lithium coin cell batteries (also known as button batteries) are much less prone to leakage than the batteries originally used on MPUs. They typically have a 10-year life span when used on an MPU. Gottlieb System 3 MPUs were the first to utilize coin cell batteries.

1.5 NVRAM

NVRAM (non-volitile RAM) is being used to replace volatile RAM installed on the MPU. Volatile RAM can only store data if power is applied to the chip. If power is lost, so is the data. NVRAM can retain data without needing any power. It is essentially "frozen" in the chip.

Various game systems use different types of RAM, so adapters are needed to adapt the footprint and pinout of the 6264 NVRAM pinout to the RAM footprint/socket that the game system is using.

NVRAM adapters typically list which RAM socket and/or game systems they are intended to support.

2 Game Systems

2.1 Allied Leisure

2.1.1 Generation 1

Game data is not saved. A battery solution is not necessary.

2.2 Atari

2.2.1 Generation 1

Game data is not saved. A battery solution is not necessary.