HAL stands for Holister Analytical Library System. It predates both LCARS and the newer ALICE systems. It is also the standard interaface on Solace Tempus ships and facilities.
Origins and History
Holister Interactive created he HAL system as a crowning achievement in computer software design, it the first successful attempt to make a computer predictively simoulate the neural network responded observed as responcible for human intelligance. Because of this, the software is polymorphic and actually rewrites its own programming code dynamically.
Starfleet had serious concerns about this aspect if its design and fear that the system could become a liability should it attain some level of self awareness by creating serious moral concerns. Starfleet chose instead to go with an early rendition of LCARS.
This was found to be a valid concern when a young Admiral Lance Thomas found a derelict colony ship the ESA Discovery orbitting a gas giant in a distant sector of the Alpha quadrant. The HAL on board had been given conflicting directives which ended up making it unable to function, the system put all its processing power into resolving the conflict resulting in the inadvertent deaths of the crew and colonists in stasis.
Possible Self Awareness
This centuries long process ended up creating a nearly self aware system, Admiral Thomas passed the technology to friend and colleague Marcus Trent-Stark for development and repair by Excalibur Inc.
Excalibur Redesign and Capabilities
In the modern incarnation the system is comparable to the ALICE interface in most ways except it does not run on top of an existing system but can mimic most known interfaces for ease of use. HAL is capable of running a ship autonomoisly in the event that the crew is incapable of doing so for some reason, though it is not sentient it is intelligent, adaptive, and has simulated self awareness.
The other major difference from other systems is that although any distinct installation of HAL can be independently developed and unique it is designed so any given installation of HAL is networked in an open database model sharing information between all branches.
HAL can be installed and operated on any device capable of running the software and self-adapts its own program code to run on different platforms, though lacking network capabilities can severely limit capabilities of some installations with limited processing and computing power. HAL is capable of interacting holographically but this is not standard in a humanoid interaction model (such as in QUINN or some ALICE systems). More common is a dybamic virtual console system for rapid delivery of large amounts of information to a living operator to manage ongoing tasks.
Almost all small ships have the capacity to run a HAL system with little or no modifications, though to run HAL on a system as a hub or major processing branch of the main hub with no, limited, or sporadic communication with other hubs require a large well powered computer core such as a Miranda Class Starship or a Solas Tempus refit Daedalus Class ship. At the minimum, due to power requirements of the computer core, refit NX or standard Oberth class suggested if a small ship is required as a hub.
Operations
Up until 2384 when the Serenity Concord enacted the ALFRE Act, HAL has been governed by the guidelines enacted by that law as well as military objectives. Until that point, HAL was governed in part by the 3 Laws of Robotics as invented by 20th century writer Issac Asimov as a basis for its moral and ethical system, though the system has a more complex system in place to avoid conflicts and make choices between laws in the rare event it becomes necessary.
On Solas Tempus facilities and ships HAL has two levels of operation. The first level is a low priority system designated for simple information input and retrieval similar to the LCARS voice interface, this level is opened for access using the voice command of computer to introduce a command. Example; "Computer, list all entries that refer to Klingon mating rituals, sort by date and author." The second is higher priority and restricted access commands that directly access and use the AI, commands here are opened by using the command HAL - for example; "HAL set a course for Alpha Centari making sure your course and speed avoid notice by Federation ships and outposts, use cloak if necessary." This is not standard in the Excalibur Inc. programming.