PAL Versions
Over the years the design and feature set of PALs has increased, as has the length of the access code. US-manufactured PALs are divided into five categories; however, the earliest PALs were never assigned a category letter.
| CLASS | Code Length | Description |
|---|---|---|
| 1 !– | 1 !3–4 | The first PALs were combination locks with a three-number sequence. Later versions used four numbers, so that the access code could be divided between two people, each of whom would only know half of the sequence. |
| 2 !A | 2 !4 | Class A PALs were electromechanical switches designed for ballistic missiles. The four-digit code was entered into the weapon using a portable electronic device. |
| 3 !B | 3 !4 | Category B PALs were essentially identical in function to Category A, but designed with newer technology. Additionally, they could be activated via a wired remote, and were thus used on weapons launched by aircraft. |
| 4 !C | 4 !6 | These PALs featured a 6-digit switch, and allowed for only limited code attempts before lockout. Such behavior was pioneered in some late model Category B PALs. |
| 5 !D | 5 !6 | Permissive Action Links in Category D had all the features of the previous generation, but also allowed for the input of multiple types of codes, including ones that could set the device to a training mode, or disable the weapon entirely. |
| 6 !F | 6 !12 | Category F PALs expand the code length to 12 digits, and disable the weapon in addition to lockout after a series of failed code entry attempts. They also include the ability to control the magnitude of the nuclear reaction (the so-called Dial-A-Yield feature) and an emergency stop. |
Read more about this topic: Permissive Action Link
Famous quotes containing the words pal and/or versions:
“The things a man has to have are hope and confidence in himself against odds, and sometimes he needs somebody, his pal or his mother or his wife or God, to give him that confidence. He’s got to have some inner standards worth fighting for or there won’t be any way to bring him into conflict. And he must be ready to choose death before dishonor without making too much song and dance about it. That’s all there is to it.”
—Clark Gable (1901–1960)
“The assumption must be that those who can see value only in tradition, or versions of it, deny man’s ability to adapt to changing circumstances.”
—Stephen Bayley (b. 1951)