Old computers were full of peculiar little details, many of them unique to the manufacturer: the LED clock showing the frequency, the Turbo button, special keys, and of course, the lock. Why was it a good idea to put locks on systems of yesteryear? Depending on the application, the goal was to prevent command entry, block access to the PC's interior, or stop it from being turned on outside working hours.
If you've ever used a pre-Windows 95 computer, you probably remember some features of its case. One of the most striking was the Turbo button. Many programs relied on the CPU frequency for their timing, and as hardware got faster, they ran too fast. "Disabling the Turbo" helped those programs recover their timing, and we were all happy.
But then there was that strange lock. “Keylock”, some models indicated. The personal computer is a convincing demonstration of technological progress, yet many units came with one of the most traditional elements of security. Why?
The Old Computers with Locks
The YouTube channel Lazy Game Reviews, dedicated to retrocomputing and classic games (among other things), explains it accurately. The most common function of the lock was to disable the keyboard. With a turn of the key, the motherboard received the order to ignore any signal, thus preventing the entry of unwanted commands.
Another of its objectives was to prevent access to the computer's interior. Bypassing the lock was as simple as disconnecting a cable with the case open, but many locks combined both functions. Certain locks had the ability to disable hard drive access, or with the use of an external accessory, block the power-on.
The first manufacturer to install a lock with tubular keys was IBM, through its 5170 computer (the classic "IBM AT"). In August 1984, the IBM 5170 cost six thousand dollars, and software-based security mechanisms were nonexistent. There were no passwords, no profiles, no remote administration. The IBM 5150 (IBM XT) had no protection, so Big Blue launched a "Keylock Option", a lock for the power switch, which also included a "dummy plug" compatible with the power connector.
The market was quick to copy IBM, and other companies adopted more robust variants, such as SGI with its metal bar. In the end, what "killed" the lock was the arrival of software-level passwords (BIOS and operating system), although users did our part by losing keys with extreme ease...
