A simulation language based on Pascal.

["PASSIM: A Discrete-Event Simulation Package for Pascal", D.H Uyeno et al, Simulation 35(6):183-190 (Dec 1980)].

passive matrix display


A type of liquid crystal display which relies on persistence to maintain the state of each display element (pixel) between refresh scans. The resolution of such displays is limited by the ratio between the time to set a pixel and the time it takes to fade.

Contrast active matrix display.

Last updated: 1995-12-09


<operating system>

A string of words and characters that you type in to authenticate yourself. Passphrases differ from passwords only in length. Passwords are usually short - six to ten characters. Passphrases are usually much longer - up to 100 characters or more.

Modern passphrases were invented by Sigmund N. Porter in 1982.

Their greater length makes passphrases more secure.

Phil Zimmermann's popular encryption program PGP, for example, requires you to make up a passphrase that you then must enter whenever you sign or decrypt messages.

Last updated: 1996-12-21



A common default password, often given out by system administrtors to new users, the hope being that they will change it immediately.

Last updated: 2011-11-22



An arbitrary string of characters chosen by a user or system administrator and used to authenticate the user when he attempts to log on, in order to prevent unauthorised access to his account.

A favourite activity among unimaginative computer nerds and crackers is writing programs which attempt to discover passwords by using lists of commonly chosen passwords such as people's names (spelled forward or backward). It is recommended that to defeat such methods passwords use a mixture of upper and lower case letters or digits and avoid proper names and real words. If you have trouble remembering random strings of characters, make up an acronym like "ihGr8trmP" ("I have great trouble remembering my password").

Last updated: 1994-10-27

Password Authentication Protocol


(PAP) An authentication scheme used by PPP servers to validate the identity of the originator of the connection.

PAP applies a two-way handshaking procedure. After the link is established the originator sends an id-password pair to the server. If authentication succeeds the server sends back an acknowledgement; otherwise it either terminates the connection or gives the originator another chance.

PAP is not a strong authentication method. Passwords are sent over the circuit "in the clear" and there is no protection against playback or repeated "trial and error" attacks. The originator is in total control of the frequency and timing of the attempts. Therefore, any server that can use a stronger authentication method, such as CHAP, will offer to negotiate that method prior to PAP. The use of PAP is appropriate, however, if a plaintext password must be available to simulate a login at a remote host.

PAP is defined in RFC 1334.

Last updated: 1996-03-23

Nearby terms:

PasqualPASROPASSIMpassive matrix displaypassphrasepassw0rd

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