Early copy protection - Apple 2, cassette tape

A nice review here of some early efforts at software protection in the consumer space, noting of course that the aim is inconvenience rather than prevention.

Cassette Copy Protection

We get a backgrounder on the Apple II and the nature of cassette storage, then three examples of protected software

Microchess was a very early chess program, released in 1978. It used the Apple II’s high-resolution graphics screen (280x192, six colors) to display the chess board. The complete game fit in 7.5K of RAM, making it easy to load from tape. Running it in a 16K machine alongside an 8K graphics frame buffer was a bit of a squeeze, but they managed it.

A company called Softape published a large number of programs for the Apple II on cassette. In 1978, they published “Module 6”, part of a series of games. This particular one was an Integer BASIC implementation of the card game “Blackjack”.

The Apple II version of Sargon II featured text and hi-res display, and required 24K of RAM. The copy protection used the best features found in the previous two examples, and took them a step further.


Very interesting. I never heard of that.
There’s also the DECO Cassette System from Data East (arcade games) with dongle and encryption.
Another interesting copyright protection had GEOS. Detailed in German here

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I don’t claim to be an Apple ][ expert, but I am a bit more sophisticated than an average consumer of cassette software, which was my only storage option in my first year of ownership.

I am familiar with several of the tricks involving loading over pages $00, $01 and $02, but a simple machine language routine that essentially listens to $C060 TAPEIN and echoes to $C020 TAPEOUT in a tight loop is probably all that would be required to refresh and duplicate any audio stream up to several KHz, obfuscated or not. A second cassette deck is the only other requirement. I never tested the theory, because my interests didn’t include cracking.

My cassette library contained mostly stuff that I typed in from magazines, but I did legally purchase Apple Invader, A2-FS1 Flight Simulator, FastGammon, Fracas and maybe a few others that I’ve forgotten. In my experience the ]['s tape system was quite reliable (faster/better and much faster/better relative to the Commodore 64 and TRS-80 respectively), and I never felt an urgent need to make backup copies.