Lenslok
The hated prism
The physical copy protection device that required players to decode on-screen codes through a plastic prism - launched on Elite in late 1985 and disliked from the first month.
Lenslok was a physical copy-protection system launched in late 1985 that required players to hold a small plastic lens against their television screen to read a two-character code. The maker, ASAP Developments, pitched it as protection that allowed back-up copies: the tape could be duplicated, but the lens could not. It had a bad first month on Elite and never shook it off.
Note on spelling: the official product name is Lenslok (no “c”), as printed on the device and on packaging. “Lenslock” is a common misspelling. Both are pronounced the same; this entry uses the correct spelling throughout.
Fast facts
- Era: 1985-1986.
- Developer: ASAP Developments Ltd, London.
- Platforms: ZX Spectrum, C64, Amstrad CPC, Atari 8-bit. Acorn User reported in November 1985 that it “could be used on BBC and Electron software”.
- Method: Plastic lens that unscrambles a column-swapped pattern of dots.
- Cost to the publisher: “a few thousand lenses cost less than 20p each” (CRASH, January 1986).
- Titles: Elite (Firebird, Spectrum — the launch title), Tomahawk and TT Racer (Digital Integration), The Music System (Rainbird, C64), The Graphic Adventure Creator (Incentive), The Price of Magik (Level 9).
- Reception: “all set to take over from turbo loaders as The Big Moan” (CRASH, February 1986).
How it worked
Sinclair User announced it in October 1985 as “a two-part system. The first part is a machine code routine which produces a code on screen which must be typed in before the software can be used. The second part is a lens which arrives with the program.” The code changed every load, and each product had its own lens: “It cannot be used with another game, even with one produced by the same company.”
Simon Goodwin explained the optics in CRASH’s Christmas Special, with diagrams from ASAP’s brochure. The lens is a group of prisms, and “the columns are always swapped in the same sequence by a given group of prisms, or ‘lens’, so it follows that a lens used to scramble the dots which make up a letter can be used to un-scramble a pattern of dots produced by swapping the columns in a letter, providing those columns have been swapped round appropriately.” The program draws two characters with their columns shuffled — “if you’ve not got the lens all you see is a jumble of dots” — and the lens shuffles them back. Two characters rather than one because “the columns which make up the two characters can be inter-mingled. Some columns on the screen are not visible through the lens at all”. With “millions of possible ‘scrambling’ patterns”, every program could have its own routine and its own lens: “It’s no good trying to use the lens supplied with Elite to get started with Digital Integration’s Tomahawk”.
In Elite:
| Step | Action |
|---|---|
| 1 | The set-up screen shows the letters “OK”; the player expands or contracts the display until it matches the width of the lens holder |
| 2 | The game displays the scrambled two-character code |
| 3 | The player holds the lens to the screen, one eye closed, looking straight into it |
| 4 | The player has ten seconds to type the two characters |
| 5 | Three failures and “the computer resets and you have to re-load the program before you can try again” |
The lenses were moulded in one piece from polystyrene “like parts for model kits”, and each came in a holder that fitted inside a cassette box.
Screen size
The set-up step is how Lenslok coped with televisions. Goodwin: “display units vary enormously — the rich and famous have crystal clear monitors, some people have old 26 inch tellies, some use black and white portables and so on.” Scaling the pattern to the lens holder told the program the size of the screen, “and hence the width of each column in the scrambled pattern — the bigger your TV, the less dots there will be in each column, since the display must be the same physical size on any set if the lens is to work.”
It worked less well than the theory. Goodwin “found that in the case of Elite, the lens worked best when the pattern was set up rather wider than the lens holder”, and CRASH’s own office found the same on a monitor two months later. The lenses “don’t work unless you look directly into them, so you can’t use them properly if your TV is on the floor or on a high shelf. They don’t work if you’ve got both eyes open, and they have to be lined up quite carefully to avoid distortion of the image.” CRASH’s news pages added that “it doesn’t work very well with very tiny telly screens and polarising or anti-glare filters on the screen can throw the system out of line a bit”.
The Elite launch
Lenslok arrived on the Spectrum Elite in late 1985 and the complaints reached CRASH’s letters pages by the February issue. One reader tried for four hours to get past the lens, took the game back, and “it took them three hours to get the code”. Another pair wrote that “Elite is the best game either of us have ever played. Lenslok is the most infuriating thing we have ever come across.” Lloyd Mangram’s verdict: “some turbo loaders just won’t load, perhaps some Lensloks just won’t unlok.” By May a reader was asking what the industry would inflict next — “Lenslok two? (AaaarghhhH!! no, spare us such terrors)!”
CRASH’s March 1986 news pages set out what had gone wrong. “Only three programs in the UK have been Lensloked so far”, and the launch title had “suffered from not one, but two mishaps”. First, “either the code used to set up the Lenslok display was incorrectly written — or at the very least, the first set of instructions that came with Elite didn’t describe the set up procedure accurately”; amended instructions later specified “a 5mm gap between the outer lines of the on-screen rules and the ends of the lens holder”. Second, “the wrong lens was shipped with some copies of Elite — fortunately for all concerned, only five hundred copies of the game were involved. Given the fact that each lens is a unique key, designed to work with a specific scrambling routine, this is rather like a hotel checking a guest in and issuing the wrong key.” A third mishap had been caught in time: one publisher “was sent an inaccurate specification of the lens they were about to use” and only discovered it “after much hair pulling” before mastering.
The same piece is not a condemnation. Digital Integration, who put Lenslok on Tomahawk, “report very few problems. But then they got the set-up code right”; CRASH called the system “the best anti-piracy device that the home computer market has seen so far” and worried that “the bad feeling generated around Lenslok” would sink the idea. Its verdict was that “painless Lensloking should be less aggravating than unloadable Turbo and Hyperloaders”.
Other titles
- The Music System (Rainbird, C64) — ZZAP! 64’s Christmas 1985 review: “It is protected by a Lenslok device, about which the least said the better…. The disks themselves can, however, be copied.”
- The Graphic Adventure Creator (Incentive) — advertised in January 1986 with “GAC incorporates the Lenslok system”; Amstrad Action’s reviewer had “problems with Lenslok — I had to reload it twice”.
- The Price of Magik (Level 9) — tested the lens during play rather than only at the start. Your Commodore: “Lenslok tests have been placed at several places in the story”. ZZAP!’s reviewer: “Apparently the dreaded Lenslok system flashes up at intervals throughout the game … I say apparently, because it didn’t do it once during the whole time I was playing”. Atari User confirmed the XL/XE version was “Lenslok protected”.
- TT Racer (Digital Integration, October 1986) — still shipping with a “Lenslok pack” a year after launch. A reader in the same issue of CRASH: “Lenslok is a pain up the butt and I once needed to re-load Elite three times”.
Cracker response
The lens protected nothing that a disassembler could not reach. Sinclair User’s launch report already said as much: “The only way for pirates to break into the system appears to be the coding system buried in the software. ASAP admits that, like any protection device, it is not 100 per cent secure”. ZZAP! noted that The Music System’s disks “can, however, be copied” — the lens guarded the program, not the medium. Removing the check meant finding the code comparison and patching it out, after which the cracked copy played identically without the lens.
Legacy
Lenslok is the standard example of protection that fell hardest on paying customers: the pirate’s copy loaded straight into the game while the buyer squinted through a prism. Even CRASH, which thought the idea sound, put the launch’s damage down to Firebird’s set-up code and packing rather than the optics.