MODE32
Encyclopedia
MODE32 is a software product originally developed by Connectix
for certain models of the Apple Macintosh. It was published in 1991 and originally cost $169, however on September 5, 1991, the software was made available free to customers under licensing terms with Apple Computer
.
. Despite the machines' hardware being designed to accommodate for this, older, non 32-bit clean software in ROM
forced these machines to run in 24-bit
mode. The "dirty" software in ROMs crippled these otherwise high-end machines to support only 8 MB of RAM. Customer dissatisfaction likely prompted the licensing agreement with Connectix.
The software runs as a control panel
in Macintosh System 7
, enabling the 32-bit addressing option of the operating system
. The option can be found in the memory control panel when MODE32 is enabled. Otherwise the option is not displayed.
For System 7.0 and 7.1, MODE 32 version 1.2 is recommended for use. In the case of System 7.5, Apple specifically recommends MODE 32 7.5 for compatibility purposes.
Generally, 32-bit addressing is only needed when large amounts of RAM are needed or when a software requires it. Running non-32-bit-clean software in 32-bit mode on any Macintosh can cause crash
es and data corruption
(see Low End Mac link below).
Other models do not need MODE32 because they either do not support 32-bit addressing at all or support it exclusively.
Connectix
Connectix Corporation was a software and hardware company, noted for having released innovative products that were either made obsolete as Apple Computer incorporated the ideas into system software, or were sold to other companies once they become popular...
for certain models of the Apple Macintosh. It was published in 1991 and originally cost $169, however on September 5, 1991, the software was made available free to customers under licensing terms with Apple Computer
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
.
Overview
MODE32 effectively removes a ROM flaw in certain models of early 68020 and 68030 Apple Macintosh computers (see below), which were advertised by Apple to be 32-bit32-bit
The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....
. Despite the machines' hardware being designed to accommodate for this, older, non 32-bit clean software in ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
forced these machines to run in 24-bit
24-bit
Notable 24-bit machines include the ICT 1900 series and the Harris H series.The IBM System/360, announced in 1964, was a popular computer system with 24-bit addressing and 32-bit general registers and arithmetic...
mode. The "dirty" software in ROMs crippled these otherwise high-end machines to support only 8 MB of RAM. Customer dissatisfaction likely prompted the licensing agreement with Connectix.
The software runs as a control panel
Control panel
Control panel may refer to:* Control panel , a flat, often vertical, area where control instrumentation is mounted.* Control panel , the tool in the operating system which allows most or all of the settings to be changed through a user interface** Control panel ** Control Panel ** Web hosting...
in Macintosh 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...
, enabling the 32-bit addressing option 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...
. The option can be found in the memory control panel when MODE32 is enabled. Otherwise the option is not displayed.
For System 7.0 and 7.1, MODE 32 version 1.2 is recommended for use. In the case of System 7.5, Apple specifically recommends MODE 32 7.5 for compatibility purposes.
Generally, 32-bit addressing is only needed when large amounts of RAM are needed or when a software requires it. Running non-32-bit-clean software in 32-bit mode on any Macintosh can cause crash
Crash (computing)
A crash in computing is a condition where a computer or a program, either an application or part of the operating system, ceases to function properly, often exiting after encountering errors. Often the offending program may appear to freeze or hang until a crash reporting service documents...
es and data corruption
Data corruption
Data corruption refers to errors in computer data that occur during writing, reading, storage, transmission, or processing, which introduce unintended changes to the original data...
(see Low End Mac link below).
Affected models
- Macintosh SE/30Macintosh SE/30The Macintosh SE/30 is a personal computer that was designed, manufactured and sold by Apple Computer, Inc. from 1989 until 1991. It was the fastest and most expandable of the original black-and-white compact Macintosh series....
- Macintosh IIMacintosh IIThe Apple Macintosh II was the first personal computer model of the Macintosh II series in the Apple Macintosh line and the first Macintosh to support a color display.- History :...
- Macintosh IIxMacintosh IIxThe Macintosh IIx was introduced by Apple in 1988 as an incremental update of the original Macintosh II model. It replaced the 16 MHz Motorola 68020 CPU and 68881 FPU of the II with a 68030 CPU and 68882 FPU ; and the 800 KB floppy drive with the 1.44 MB SuperDrive...
- Macintosh IIcxMacintosh IIcxHalf a year following the release of the Macintosh IIx passed before Apple introduced the Macintosh IIcx in 1989. Despite resembling the IIx to a great extent and providing the same performance, the IIcx was quieter than its predecessor. The design was also made much more compact by reducing the...
Other models do not need MODE32 because they either do not support 32-bit addressing at all or support it exclusively.