Why did computers in the 90's have a lock and what did it do?
In the 1990s, a lot machinery, IBM compatible PCs included a lock in their case, right next to the Turbo and Reset buttons. What did these locks do and why were they there? Let's find out!
The era before passwords
In the early 1980s, computers that were compatible with IBM computers were largely single-user machines running MS-DOS, and did not include some sort of built-in password protection. Anyone sitting in front of your computer could start it and gain access to all your data.
As today, computers were often running server software or intensive tasks, which could take a long time to complete. If you had to leave, of course you would not want someone to come and press a button to interrupt the process, right? Today, you would just lock your computer with a password, but then, you did not have that option.
So came the keyboard lock (or "keylock", as IBM called it).
From about 1984 until the mid to late 90's, many computer cases included one small tubular lock with pin in the front panel. It was usually located near the Turbo and Reset buttons.
When connected (because the PC builder sometimes skipped this step), these locks prevented the keyboard from being used. You could type whatever you want, but the computer would not listen.
On some systems, this lock also prevented a computer from starting when it was locked, resulting in an error.302-System Unit Keylock is Locked".
The origin of the keyboard lock
The keypad lock can be found on IBM and mainframe servers, which preceded the company's computers. A natural lock was a security measure to prevent unauthorized use.
Keyboard lock came from IBM Personal Computer AT, an expensive machine based on 286, released in 1984. IBM, with its $ 4.000- $ 6.700 machine (approximately $ 10.000- $ 16.800 today), was initially aimed at small business professionals, but its new features soon became the de facto standard on compatible computers.
When IBM included a small lock on the front of the AT computer, they followed the clone manufacturers, introducing their own keyboard locks on AT-compatible machines. They added the lock to include features that were equivalent to IBM machines and also to maintain compatibility with its systems. Compatibility was a key selling point for computer clones at the time.
For the IBM AT PC, the lock on the front of the case not only deactivated the keyboard and interrupted the boot process, but also moved an internal metal flange. This prevented the metal case of the computer from opening.
In the many IBM computer clones that followed, only high-tech machines tended to replicate the ability to lock a case. On most other computers, the lock simply turned off the keyboard.
The twilight of the keyboard lock
As smart as a computer case with a lock was, few people actually used it. As the PC clone market became more and more important, with less profit margins, computer manufacturers began to cut features. The old-fashioned special features that few people used, such as the keypad lock and the Turbo button, stopped.
Keyboard locks were not really favored in the mid-90s. Passwords have reached modern multitasking operating systems, such as Windows NT, Novell NetWare, Linux and (to some extent) Windows 95. The latter used, for the most part, passwords to store personal preferences, rather than for security.
Who needs an expensive hardware lock when they have the software?
BIOS passwords also became a common feature for computer clones in the mid-90s. There was now a software-based way to prevent unrelated people from starting a computer.
With operating system passwords and BIOS passwords widely available, keypad lock is no longer useful. It finally disappeared in the mid to late 90s. The last computer clone we saw with a keyboard lock was sometime in 1996.
Lost your key? How to bypass a vintage keyboard lock
If you have an old IBM compatible computer that is locked and you have lost the key, there are some solutions. First, you obviously should never try to bypass a lock on a computer without the owner's permission. It is rather illegal. Only do this on a vintage machine that you legally own or have permission to unlock.
If it is just a keypad lock and does not lock the case naturally, you can open the computer case and find the two cables leading from the keypad switch to the motherboard. Gently disconnect their plug from the motherboard. After doing this, you should be able to use the computer.
If the case and keyboard are locked, then this is a different story. You may want to consult a locksmith. If you try to break the lock with sharp tools, you will probably spoil it.
Alternatively, you may be able to purchase a spare key for your machine. Check out eBay and search the web. Keep in mind, however, that different computers used locks with different hole diameters, so there is no guarantee that a particular key will work with your system.