MultiFinder
Encyclopedia
MultiFinder was the name of an extension
software for the Apple Macintosh, introduced on August 11, 1987 and included with System Software 5. It added the ability to co-operatively multitask between several applications at once – a great improvement over the previous systems, which could only run one application
at a time. With the advent of System 7
, MultiFinder became a standard integrated part of the operating system
. It remained a part of the operating system until Mac OS X
.
(128 kB
) that Apple's developers decided early on to abandon the multi-tasking that Apple had developed for the Lisa
.
, such as a calculator, that could be run concurrently. However, these were deliberately limited so that they would not use up too much of the available RAM
. In fact, they were device drivers which took advantage of the limited multitasking system designed for hardware peripheral support. Although the system software did little to specifically support them, the popularity of Desk Accessories led many application developers to ensure good cooperative multitasking support even from the early days.
which came standard with 1 MB
of RAM. This amount of memory was sufficient to support some form of multitasking, which was first implemented by Andy Hertzfeld
in his Switcher program, demoed in January 1985 on a Macintosh 512k, and released as a beta in April 1985. Switcher worked by designating a number of fixed "slots" in memory, into which applications could be loaded. The user could then switch between these applications by clicking a small button on the top of the menu bar
. The current application would horizontally slide out of view, and the next one would slide in. Despite its awkwardness, this approach did fit well with the existing system's memory management
scheme, and applications needed no special programming to work with Switcher. This early work on Switcher led to the development of MultiFinder by Apple system software engineers Erich Ringewald and Phil Goldman
.
with many of the windowing data structure
s that were already documented. It also provided a way for applications to supply their memory requirements ahead of time, so that MultiFinder could allocate a chunk of RAM to each according to need. This scheme, while functional, turned out to have severe limitations which caused many problems for users (see Mac OS memory management
for more details).
With the release of System 7
, the MultiFinder extension was integrated with the operating system, and it remained so in Mac OS 8
and Mac OS 9
. However, the integration into the OS did nothing to fix MultiFinder's inherent idiosyncrasies and disadvantages. These problems were not overcome until MultiFinder was abandoned with the move to a modern preemptive multitasking UNIX
-based OS in Mac OS X
.
Extension (Mac OS)
On the Apple Macintosh operating system prior to Mac OS X, extensions were small pieces of code that extended the system's functionality. They were run initially at start-up time, and operated by a variety of mechanisms, including trap patching and other code modifying techniques. Initially an...
software for the Apple Macintosh, introduced on August 11, 1987 and included with System Software 5. It added the ability to co-operatively multitask between several applications at once – a great improvement over the previous systems, which could only run one application
Application software
Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...
at a time. With the advent of System 7
System 7 (Macintosh)
System 7 is a single-user graphical user interface-based operating system for Macintosh computers. It was introduced on May 13, 1991 by Apple Computer. It succeeded System 6, and was the main Macintosh operating system until it was succeeded by Mac OS 8 in 1997...
, MultiFinder became a standard integrated part of the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
. It remained a part of the operating system until Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
.
History before the MultiFinder
The first Macintosh, released in 1984, had such limited memoryRam
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
(128 kB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
) that Apple's developers decided early on to abandon the multi-tasking that Apple had developed for the Lisa
Apple Lisa
The Apple Lisa—also known as the Lisa—is a :personal computer designed by Apple Computer, Inc. during the early 1980s....
.
Desktop Accessories
To allow some degree of freedom, the original Macintosh included Desk AccessoriesDesk Accessory
A desk accessory is a small helper-type application that can be run concurrently with any other application on the system. Early examples, such as SideKick and Macintosh desk accessories, used special programming models to provide a small degree of multitasking on a system that initially did not...
, such as a calculator, that could be run concurrently. However, these were deliberately limited so that they would not use up too much of the available RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
. In fact, they were device drivers which took advantage of the limited multitasking system designed for hardware peripheral support. Although the system software did little to specifically support them, the popularity of Desk Accessories led many application developers to ensure good cooperative multitasking support even from the early days.
Switcher
In 1986, Apple released the Mac PlusMacintosh Plus
The Macintosh Plus computer was the third model in the Macintosh line, introduced on January 16, 1986, two years after the original Macintosh and a little more than a year after the Macintosh 512K, with a price tag of US$2599...
which came standard with 1 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...
of RAM. This amount of memory was sufficient to support some form of multitasking, which was first implemented by Andy Hertzfeld
Andy Hertzfeld
Andy Hertzfeld is a computer scientist who was a member of the original Apple Macintosh development team during the 1980s. After buying an Apple II in January 1978, he went to work for Apple Computer from August 1979 until March 1984, where he was a designer for the Macintosh system software...
in his Switcher program, demoed in January 1985 on a Macintosh 512k, and released as a beta in April 1985. Switcher worked by designating a number of fixed "slots" in memory, into which applications could be loaded. The user could then switch between these applications by clicking a small button on the top of the menu bar
Menu bar
A menu bar is a region of a screen or application interface where drop down menus are displayed. The menu bar's purpose is to supply a common housing for window- or application-specific menus which provide access to such functions as opening files, interacting with an application, or displaying...
. The current application would horizontally slide out of view, and the next one would slide in. Despite its awkwardness, this approach did fit well with the existing system's memory management
Mac OS memory management
Historically, the Mac OS used a form of memory management that has fallen out of favour in modern systems. Criticism of this approach was one of the key areas addressed by the change to Mac OS X....
scheme, and applications needed no special programming to work with Switcher. This early work on Switcher led to the development of MultiFinder by Apple system software engineers Erich Ringewald and Phil Goldman
Phil Goldman
Phillip York "Phil" Goldman was an American engineer and entrepreneur best known for co-founding WebTV.-Early life:Growing up in San Mateo, California, Goldman attended San Mateo High School graduating in 1982...
.
MultiFinder
MultiFinder, introduced on August 11, 1987, extended the system in a number of significant ways. In addition to giving each application CPU time, it provided a way for windows from different applications to co-exist by using an application layering model. When an application was activated, all of its windows were brought forward as a single layer. This approach was necessary for backward compatibilityBackward compatibility
In the context of telecommunications and computing, a device or technology is said to be backward or downward compatible if it can work with input generated by an older device...
with many of the windowing data structure
Data structure
In computer science, a data structure is a particular way of storing and organizing data in a computer so that it can be used efficiently.Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks...
s that were already documented. It also provided a way for applications to supply their memory requirements ahead of time, so that MultiFinder could allocate a chunk of RAM to each according to need. This scheme, while functional, turned out to have severe limitations which caused many problems for users (see Mac OS memory management
Mac OS memory management
Historically, the Mac OS used a form of memory management that has fallen out of favour in modern systems. Criticism of this approach was one of the key areas addressed by the change to Mac OS X....
for more details).
With the release of System 7
System 7 (Macintosh)
System 7 is a single-user graphical user interface-based operating system for Macintosh computers. It was introduced on May 13, 1991 by Apple Computer. It succeeded System 6, and was the main Macintosh operating system until it was succeeded by Mac OS 8 in 1997...
, the MultiFinder extension was integrated with the operating system, and it remained so in Mac OS 8
Mac OS 8
Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It represented the largest overhaul of the Mac OS since the release of System 7, some six years previously. It puts more emphasis on color than previous operating systems...
and Mac OS 9
Mac OS 9
Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
. However, the integration into the OS did nothing to fix MultiFinder's inherent idiosyncrasies and disadvantages. These problems were not overcome until MultiFinder was abandoned with the move to a modern preemptive multitasking UNIX
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
-based OS in Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
.
External links
- Folklore.org — Andy Hertzfeld himself on how the Switcher idea was born and fortunately ended up in the hands of Bill Gates