44 votes
Accepted

How were Amiga games cracked circa 1987?

But at the time, with really primitive tools, how was it done? I can only speak for myself, but I suspect it was the same for most - we just used those really primitive tools - and our brains. All ...
Bruce Abbott's user avatar
  • 6,673
32 votes
Accepted

How does "bit-slip" copy protection work?

The Apple II reads disk tracks as a continuous stream of bits. To make sense of the data, it's necessary to figure out where individual bytes start. This is done with self-sync bytes. Standard self-...
fadden's user avatar
  • 9,040
28 votes
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How did "full memory" Spectrum tape copiers work?

These programs usually had a mono-color background with very little text. By setting the color of the screen as "black ink on black paper" or "white ink on white paper", it is possible to relocate the ...
Sklivvz's user avatar
  • 1,233
24 votes

How did "full memory" Spectrum tape copiers work?

There are multiple techniques used by tape copy programs to be able to copy large blocks of data. By large we mean close to the whole RAM capacity (48 KiB) or even more! Using maximum of the ...
pabouk - Ukraine stay strong's user avatar
23 votes
Accepted

Which software was the first to use copy protection?

I couldn't say which one was the first but there were early efforts in the 1970's and 1980's Encrypted roms Arcade games were often hacked so ROM encryption was developed, so if the board was re-made ...
Jean-François Fabre's user avatar
22 votes

Copying tapes "back in the day"

In theory, it is fairly simple duplicating a tape. The problem with analog tape-to-tape copies is that sound quality lowers and spurious noises are also copied and more are generated into each new ...
Rui F Ribeiro's user avatar
22 votes

How did Apple II BASIC programs protect against listing?

If I recall correctly, there were lots of variations to implement this scheme. Besides embedding characters in the listing that would reboot, or clear the screen every so often, a particular one I ...
dirkt's user avatar
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20 votes
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Disk copy protection schemes for Apple II

That question is kind of overly broad, as it essentially asks to explain all ways a floppy image can be composed and written - which is next to infinit. A short search may turn up quite a lot of hits. ...
Raffzahn's user avatar
  • 223k
18 votes

How did Apple II BASIC programs protect against listing?

There were multiple ways of protecting the program, including: order of line numbers could be altered to produce: circular listings; missing lines; out-of-order lines; out-of-bounds addressing; ...
peter ferrie's user avatar
  • 1,314
18 votes

How was Prince of Persia "better/faster" with RWTS18?

The assertion that 4x4 is faster is false, it's easier, yes, but not faster. RWTS18 could read the entire track in one revolution so it is the fastest. I know that 4x4 and 6x2 were also capable of ...
rolandgust's user avatar
18 votes
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Weak bits on floppy for copy protection

"Weak bits" are a means of copy protection that generates areas on a disk that read back as random values, without the floppy disk controller actually detecting an error. When copying such a weak bit ...
tofro's user avatar
  • 35k
17 votes
Accepted

What's the point of the CPS-2 suicide battery?

This was an anti-piracy measure. If a "bootlegger" wanted to duplicate the board, they would only have access to encrypted ROMs, thus making it impossible to reproduce the arcade board with ...
Brian H's user avatar
  • 60.8k
16 votes

Which software was the first to use copy protection?

One of the earliest would likely have been Microchess 2.0 for the Apple II, shipped on cassette in 1978. Andy McFadden's Early Copy Protection on the Apple II article has the details.
scruss's user avatar
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15 votes
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Did RapidLok etc knock floppy drives out of alignment?

Many home computer floppy drives (some 1541 variants, and also e.g. Apple II drives) had no track zero sensor. That means the only way to get them to a known position was indeed to hammer them ...
dirkt's user avatar
  • 27.3k
14 votes
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How can I view BASIC code hidden by SYS?

SYS is the BASIC instruction to execute a routine written in machine code. There is no more BASIC code to view, the entire game is implemented as a machine code program, and the BASIC only exists as ...
Jules's user avatar
  • 12.9k
13 votes

Was the Amstrad's file protection considered secure in 1985?

Secure? No, but much more so than protected BASIC programmes on tape, which merely had a single field set in the tape header that triggered the run once then NEW behaviour. It would definitely have ...
scruss's user avatar
  • 21.6k
13 votes

Why does changing a DOS/Windows EXE cause it to not run?

If you change the lengths of strings in a binary, or indeed move any part of a binary around in any way, then you’re likely to break it: offsets to the data (and code) that the program expects to find ...
Stephen Kitt's user avatar
13 votes

How were Amiga games cracked circa 1987?

Same method as used on the early PC's (those with 10-20mb boat anchor hard discs), those things even hadn't a gui. Completely manual disk debugging. Reading in boot record, then following code with ...
HermDP's user avatar
  • 383
12 votes

Copying tapes "back in the day"

No, you won't need any 'HiFi' like recorders. After all, these were the very same devices you also used to record your own programs and/or data. While copying from recorder to recorder does always ...
Raffzahn's user avatar
  • 223k
12 votes
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How was Prince of Persia "better/faster" with RWTS18?

Less disk swapping, but also faster loading. Much of the performance improvement in Apple II fast DOS implementations (including ProDOS) was due to less latency between reading sectors - and this ...
Nick Westgate's user avatar
12 votes

How were Amiga games cracked circa 1987?

I'd like to point out that in those times, even though it could seem complicated, encryption algorithms often were nowhere near what they are today. While most of the theory behind good encryption was ...
PMF's user avatar
  • 451
10 votes

How did "full memory" Spectrum tape copiers work?

Assuming a program consisting of a unique big block of 49152 bytes (the whole RAM space). A routine that may be used for a copier to copy this block would sit at the top memory, say at address 64000 ...
mcleod_ideafix's user avatar
10 votes

Were commercial Amiga floppy disks shipped with write protection?

I bought a lot of original games and the floppies were always write protected from the start. I also remember the message that appeared a lot in manuals: ALWAYS KEEP YOUR DISKS WRITE PROTECTED (just ...
Jean-François Fabre's user avatar
10 votes

Disk copy protection schemes for Apple II

I remember Locksmith, too, and I actually still have it on floppy somewhere. There was a wide variety of protection schemes, from "let's use non-standard code for GCR address and data marks" ...
dirkt's user avatar
  • 27.3k
9 votes

How did "Super Wonder Boy (in Monsterland)" defeat the Multiface One?

A partial answer: the Multiface provides both its own ROM and its own work RAM which it pages in just below the screen area. Per the For UNIX Spectrum Emulator ('FUSE') source code this 8kb of RAM can ...
Tommy's user avatar
  • 36.9k
8 votes

Disk copy protection schemes for Apple II

You can find some detailed descriptions below. There are two primary classes of protections that Locksmith could not duplicate - "E7" and "weak bits", the first of which was used ...
peter ferrie's user avatar
  • 1,314
7 votes

Was the Amstrad's file protection considered secure in 1985?

I'm not familiar with that system, but if users had the ability to protect their own files, then no it was not secure. If you can protect your own files (with known contents) then you have easy ...
Ken Gober's user avatar
  • 11.4k
7 votes

Why does changing a DOS/Windows EXE cause it to not run?

Adding or removing some text has the effect that things coming later in the EXE file are now found at a different absolute location, machine code as well as the EXE file format rely a lot on absolute ...
Ralf Kleberhoff's user avatar

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