Re: [stella] Games using unofficial opcodes

Subject: Re: [stella] Games using unofficial opcodes
From: "Robin Harbron" <macbeth@xxxxxxxxxxx>
Date: Wed, 1 Jun 2005 21:25:40 -0400
On Wed, 1 Jun 2005 13:01:15 -0400
 Glenn Saunders <mos6507@xxxxxxxxx> wrote:
>I'd be interested in knowing how early the use of
>illegal opcodes started and for which platforms.  I
>vaguely recall that the practice may have originated
>in the C=64 'scene'.

The earliest use of illegals that I've encountered was in
the disk loader/copy protection of "Blockade Runner" for
the C64.  I de-protected this game late last year, after
discovering it in a collection of disks I found at a
thrift shop - the game was previously thought unfinished/
unreleased (but now I'm getting OT).

The copy protection was created in late '83 or early '84,
and the main use of illegals seemed to be obfuscation, to
throw pirates off the trail while dissassembling.

Along with a top-notch 2600 kernal, copy protection schemes
are the most hard-core 65xx code I've seen.
Archives (includes files) at
Unsub & more at

Current Thread