Technical Note OV505

Compatibility Q&As

CONTENTS Macintosh Install Me First disk model-specific files Number suffix in system enabler file name Whether to develop for Macintosh System 6 Downloadables

This Technical Note contains a collection of archived Q&As relating to a specific topic--questions sent the Developer Support Center (DSC) along with answers from the DSC engineers. Current Q&As can be found on the Macintosh Technical Q&As web site. [May 01 1993]

Macintosh Install Me First disk model-specific files

Date Written: 1/11/93

Last reviewed: 6/14/93

Are there any differences in the System 7.1 that ships with the PowerBook 160? For example, can I use the 7.1 disks that come with recent Macintosh models to upgrade other machines?

The Install Me First disk that comes with the PowerBook Duos, PowerBooks 160 or 180, Macintosh IIvi, Macintosh IIvx, and later Macintosh models contains model-specific system files, called System Enablers. The Install disk and the other disks in the set are identical to the disks in the System 7.1 Update Kit.

The Install Me First disk included with models introduced after mid-October 1992 has a special system "Enabler" file, which is necessary for System 7.1 to work with that particular model. Without the Enabler, the CPU will not boot. The Install Me First disk also can have control panels, extensions, and other files that are specific to each model. For example, the PowerBook 160, 180, and Duo models have an Auto Remounter control panel for reconfiguring network connections.

Install Me First contains the familiar Macintosh system software installer script. If a user selects Easy Install, the installer first loads the system enablers and other model-specific system files located on Install Me First. Then it queues the Install disk--normally the first disk in the System 7.1 installation process. Thus, the Install Me First disk is primarily the vehicle to deliver the system enabler and the extra control panels, and other model-specific system files. This Install Me First disk is different for each model, since the system enablers are different.

One last point: Install Me First contains a minimal system; it's a bootable disk. This allows you to do an installation from the disk. (Note: System enablers are not included in the System 7.1 Update Kit.)

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Number suffix in system enabler file name

Date Written: 1/11/93

Last reviewed: 4/1/93

I see that system enablers end in numbers, such as "System Enabler 111." Does that mean that when Apple comes out with "System Enabler 112" or higher that I should replace a system enabler file if it has a lower number?

No, you shouldn't replace the system enabler already installed in your machine. Each system enabler is model-specific. Although the name doesn't reflect which model it's specific for, a system enabler file should be used only with the model it came with. The enabler is located on the Install Me First disk that comes with CPUs released on or after October 19, 1992. You can also find copies on the Developer CD Series as of the April issue.

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Whether to develop for Macintosh System 6

Date Written: 12/15/92

Last reviewed: 3/1/93

What's Apple's position on support for Systems 6 and earlier? Is such support still recommended for compatibility reasons, or is Apple letting developers make the call? Would it be considered a serious mistake to write software that's System 7 dependent? If Apple still recommends support for System 6, for how long will such support be recommended?

It's a tough call. Apple's standard position is that we support the most current version of system software, which is now System 7. However, we all know that not everyone in the world uses System 7. Also, Apple traditionally prefers to put choices in the hands of the user rather than presuming to make those decisions for the user. So essentially what Apple promotes may not necessarily be what our users are able to support.

A safe, general rule is to offer compatibility with 6.0.7 as the minimum. And yes, we have faith that our developers will decide which system software version would be best suited for users.

So this is one of those issues on which it's very hard to take a firm stand. Although Apple's perspective on the present and future is to promote System 7 all the way, and Apple takes every opportunity to encourage System 6.x users to upgrade to System 7, the decision is ultimately yours. (And we trust your good judgment!)

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Downloadables