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Can you jailbreak the Commodore C64?

Published 28 April 2018


There has been an ongoing war between manufacturer's and hackers to lockdown proprietary systems. The recent news of the Nintendo Switch™ being jailbroken through an un-patchable exploit (link to news item) got us thinking about jailbreaking our wonderful Commodore C64. Can it be done? Why hasn't it been done already?

What is Jailbreaking?

Jailbreaking is computer jargon for bypassing digital rights management or other developer restrictions that stop users from running homebrew software or modifying the product to use non-proprietary tools. Many manufacturers create walled-gardens of their systems to maintain control and quality of software and hardware for their platform. The Nintendo Switch™ has made news recently when an unpatchable exploit (wayback) allowed committed hackers to jailbreak this platform as well.

Jailbreaking the Commodore C64

Reasons to Stop Jailbreaking

The act of jailbreaking may brick your equipment. There are numerous laws around the world that enforce restrictions. Apart from that, there are three main reasons to implement jailbreak restrictions.

  1. The obvious reasons is $$ money $$. Manufacturers make money my licensing the rights to third party developers, that users pay for in the in by higher retail prices.
  2. There is also the legitimate concern about quality. A manufacture's product may be aimed towards the children's market and will want to make sure that all third-party products meet the expected standards for the market.
  3. The final reason is system security. Consumers have come to expect their system to be somewhat resistant to hacking and maintaining privacy. It has become increasingly easy for malicious developers to create apps to steal private data and create zombie machines for cyber-attacks.

The conversation is not all one-way. The Electronic Frontier Foundation (EFF) is running an interesting campaign to promote awareness of manufacturer restrictions, called the Catalog of Missing Devices (wayback).

What systems are jailbroken?

Some say that the jailbreaking term actually came from the iOS jailbreak movement (wayback) and has spread to other systems. The current big-daddy systems include, Apple's iOS™, Sony PlayStation™ Portable and Sony PlayStation™ series.

Once systems are jailbroken then they are generally used for installing alternative operating systems, such as Linux, side-loading homebrew software, or just creating technical demonstrations.

Jailbreaking the Commodore C64

When we started preparing for this article we thought that it was a no-brainer that nobody had bothered to jailbreak a Commodore C64. On the surface Commodore promoted third-party software developers and, let's face it, the Commodore Kernal (wayback) was pretty bare bones and only occupied 8KB. What possible restrictions were implemented that needed to be jailbroken?

Well stay with us for a moment. The essence of jailbreaking is to work around intended restrictions to open up new and unintended applications. With that in mind, we list our top 5 jailbreak applications on the Commodore C64.

  1. Freeze Cartridges such as Action Replay - These cartridges were sometimes referred to as cheating devices to create the ability to perform a software reset or dump the memory to disk. This is the ultimate jailbreaking equipment, dating back to the early 1980s.
  2. GEOS - This is not the obvious jailbreaker example but what do you do when the Commodore C64 doesn't have a graphical operating system for you to use? You jailbreak from the supplied Commodore Kernal and create GEOS, the Graphical Environment Operating System. Here, users can break from the official Commodore developed system into something that gives the user more freedom.
  3. Hacking software scores and trainers - Using codes that changed parts of a game code, called POKES, hackers were able to overcome game restrictions to get unlimited lives, avoid sprite collision detection, and give characters more capabilities. Games became more difficult as players progressed to new levels and codes made it easier to complete the game that were otherwise impossible.
  4. Overcoming disk copy protection systems - Pirate game distribution was rife during these halcyon days. Friends copied disks containing games and demos. It was considered as just part of the scene. In order to overcome copy protection, hackers would jailbreak code and floppy disc routines to creaked cracked copies. This led to an extension of the demoscene called Crack Intros.
  5. Illegal opcodes - the Commodore, like most 8-bit systems, were not particularly fast and cutting edge games regularly worked to extend the boundaries of software development. Over time, discovered illegal opcodes that can be utilized to speed up operations, but with sometimes with crazy side effects. These codes were never endorsed by Commodore and not intended to be used. Sometimes they were not even real commands but firmware bugs or manufacturing defects that allowed these codes to work. You might have used jailbreak technology when playing the latest shoot-em ups.
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