MODE32
MODE32 was a software that was originally manufactured by Connectix for some models of the Apple Macintosh. It was sold from 1991 at a price of U.S. $ 169 until the software was available for free on 5 September 1991 under the license terms of Apple Computer.
Overview
MODE32 fixes a bug in the ROM of some early Mac models (see below ) of the years 1989 to 1990 was included. He prevented the use of more than 8 MiB RAM under System 7 These computers were originally developed at times when the operating system was not yet 32 -bit -capable and therefore the time on Mac usual 24 -bit addressing was used. After the release of System 7, this error came to fruition, as about the Mac SE/30 could be equipped with up to 128 MiB of RAM.
Connectix offered troubleshooting for sale until the customer dissatisfaction Apple led to a licensing agreement with Connectix.
The software installs itself as a check box in System 7 and allows the selection of "in the memory control panel option" 32 -bit addressing. Without MODE32 this option is not available.
MODE32 is needed on the affected models only under System 7, and only when more than 8 MiB RAM. Subsystem 6 Connectix OPTIMA can be used to use more than 8 MiB for programs, or maxima for a RAM disk in this area. Very old Mac software, typically prior to 1990, may not be 32-bit and adapted to be operated in the 24- bit mode.
32- Bit Compatibility
For 24 -bit programs when the Motorola 68000 processor have not been used by connecting cables to the outside out upper 8 bits of the address register for internal purposes. The use of such software on true 32 -bit platforms leads to faulty addresses of memory accesses. The lack or limited memory protection system 7 starting such a program usually drew the immediate crash by itself.
Affected devices
- Macintosh SE/30
- Macintosh II
- Macintosh IIx
- Macintosh IIcx
All other Macs do not need MODE32 because they dominate either no 32 -bit addressing, MiB RAM are not more than 8 mountable or the ROM has already been delivered error-free and thus offers the 32 -bit mode itself.