| Technote OV 21 | March 1995 |
System 7.5 includes the Scriptable Finder, which permits users to automate system tasks with their scripts. Several sample automated tasks are included in the "Automated Tasks" and "More Automated Tasks" folders, together with several new `osax's.
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Apple Guide is Apple's electronic assistant that guides users through procedures one step at a time. You can create Apple Guide files for your applications using the Guide Maker authoring tool; Apple Guide also works with AppleScript to create Guide scripts.
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The Display Manager allows users to dynamically change the arrangement and display modes of the monitors attached to their Macintosh computers. The Display Manager is documented in Inside Macintosh: Advanced Color Imaging in the Display Manager chapter. Preliminary copies of this documentation are on the developer CD.
Drag Manager 1.1
Macintosh Drag and Drop permits users to select a block of data and drag it to another location, either on the Desktop or in a file, even in other applications. Macintosh Drag and Drop is integrated into the System 7.5 System file.
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The Control Strip originally introduced in the PowerBook 540/520 series has been extended to all Macintosh PowerBook computers.
The Power Manager gives Macintosh PowerBook users additional control over the power management settings that currently are available in the PowerBook control panel. The application programming interface (API) is documented in the following documents in the Power Manager folder:
System 7.5 supports Macintosh computers, whether they use a Motorola 680x0 processor or a PowerPC processor. System 7.5 includes additional PowerPC native interfaces and software, including the Drag Manager, Thread Manager, Macintosh Easy Open, PowerTalk, and QuickDraw GX.
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QuickDraw GX implements more intuitive printing and advanced text and graphic support. QuickDraw GX also provides for "portable digital documents" (PDDs) that do not require the presence of the creating application in order to open the file.
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The Telephone Manager is part of the Macintosh Telephony Architecture (MTA), which provides a framework for the integration of personal computers and telephones.
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The Thread Manager is a System 7 extension that allows applications to make use of multithreading on Macintosh computers. Thread Manager 2.0 provides support for PowerPC. The Thread Manager is integrated into System 7.5's System file.
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The Installer permits application developers to write scripts that allow users to easily install their applications. An Installer script is written using the MPW (Macintosh Programmer's Workshop) Rez language, and compiled using the MPW Rez tool. The Installer 4.0.3 SDK is included on the developer CD, or on the MacOS SDK CD-ROM.
SCSI Manager 4.3
SCSI Manager 4.3 provides asynchronous SCSI to all Quadra and Centris systems for the first time. In addition to the capabilities of the former SCSI Manager, the SCSI Manager 4.3 additionally:
File System Extensions
File System Extensions is a set of patches to the Finder and HFS which raises the current maximum volume size of 2 GB to 4 GB by treating volume sizes as unsigned values. It affects all Macintosh systems.
* The exact upper limit of a volume's size is 4063 MB. This is due to the fact that the allocation block size must be a multiple of 512 bytes, and is treated as an unsigned short in HFS. (It's stored as a long, and documented as a long, but actually treated as an unsigned short.) This means that the maximum allocation block size is $FE00. The maximum number of allocation blocks is $FFFF. Multiply these together to get 4063 MB.
* The File Manager's routines to extend and truncate files had math problems and would fail if the physical end-of-file was close to the 2 GB file size limit - the math problems were fixed. The bug wasn't seen under System 7.1.x and earlier systems because volumes were always less than 2 GB and files could never get large enough to show the bug because of the disk space used by the Catalog and Extents Overflow files.
* The PBHGetVInfo call was changed to pin the number of allocation blocks and free allocation blocks reported. For example, if the allocation block size is 0xfe00 (the largest possible under System 7.5), the total number of allocation blocks and number of free allocation blocks is pinned to 0x8102. This change was made because a significant number of programs use signed math to determine the volume size and free space and they didn't work if the real values were returned. The volume's Volume Control Block (VCB) still contains the real number so code that needs the real value can still get to it. See the DTS sample code MoreFiles for a routine that shows how to access the VCB to get the actual number of allocation blocks.
* The Finder's code that calculates volume size and free space was patched to use unsigned math.
* The gestaltFSAttr Gestalt selector has a new bit defined to indicate when the 4 gigabyte changes have been made, gestaltFSSupports4GBVols. Here's a complete list of the gestaltFSAttr bits that are currently defined. Not all are in use at this time (i.e., gestaltFSSupports2TBVols).
gestaltFSAttr = 'fs ', /* file system attributes */
gestaltFullExtFSDispatching = 0, /* all HFSDispatch selectors are passed
through to file systems */
gestaltHasFSSpecCalls = 1, /* File Manager has FSSpec calls */
gestaltHasFileSystemManager = 2, /* has the File System Manager */
gestaltFSMDoesDynamicLoad = 3, /* File System Manager supports dynamic
loading */
gestaltFSSupports4GBVols = 4, /* file system supports 4 gigabyte volumes */
gestaltFSSupports2TBVols = 5, /* file system supports 2 terabyte volumes */
gestaltHasExtendedDiskInit = 6, /* has extended Disk Initialization calls */If a greater than 2 gigabyte volume is mounted under System 6, System 7.0.x, or System 7.1.x, nothing bad should happen. Some programs, including the Finder, will not work correctly because of their signed math problems and files that are close to the 2 gigabyte file size limit may not be usable.
The following hints are recommended to writers of device drivers
* Make sure your disk driver always uses ioPosOffset as a unsigned long value. This allows access to 4GB offsets. The File Manager will never use negative offsets.
* When allowing a user to partition a volume 2 gigabytes or larger, put up a informational dialog to make sure they are aware that the volume should be used only with System 7.5 or later.
* Your driver should set the dNeedTime bit in the drvrFlags. The first time your driver receives an accRun Control request, it should call gestalt with the gestaltFSAttr selector and check the gestaltFSSupports4GBVols bit. If 4 gigabyte volumes are not supported, then you should use the Notification Manager to let the user know that this disk should not be used with systems earlier than System 7.5.
Note: Apple's driver and Apple HD Setup do not implement the second and third suggestions above.
System Update 3.0 bug fixes and enhancements
System Update 3.0 is a collection of bug fixes and enhancements delivered as part of the System file. Under System 7.5, it is no longer a separate file. Technical Note "OS 05 - System Update 3.0" describes these bug fixes and enhancements.
SimpleText
The application known as TeachText has been greatly enhanced and renamed SimpleText; it is the integration of many changes made by various engineering groups at Apple.
Integrating existing behavior means that not all behavior has been modified; also, despite some significant improvements SimpleText remains considerably less than a full-fledged word processor. Its footprint is now 25K smaller, although the recommended RAM size is now 512K.
SimpleText is designed to serve as the standard version of TeachText for users of System 7.5 and beyond.
SimpleText/TeachText Changes
Note that some changes were implemented prior to the name change to SimpleText. With these changes, SimpleText now:
System 7.5 includes the following improvements in speed and performance:
Process ManagerThe System 7.5 version is a superset of the version that shipped with PowerTalk. Among other improvements, this version of the Process Manager switches context faster than previous process Managers, resulting in a better user experience.
Faster File CopyingA change was made to the buffer size that the Finder uses. Note that this is only for file copying from hard disk to hard disk (files copied to and from floppies or foreign file systems are not affected).
Opening windowsThis change is for windows in the Finder that have a large number of files (greater than 100). As the number of files increase this speed-up should be noticeable to the user.
File System CacheThe cache now consolidates contiguous blocks before writing, reducing internally the number of driver calls necessary to flush the cache.
Menu ManagerThis is an enhancement to the former MDEF; it now caches menus that have been drawn. The result is that the next time a menu is pulled down, it is drawn immediately. The results vary according to the speed of the CPU. On slower machines, the effect is quite dramatic.
The following System Software Components are included as part of System 7.5:
These features were originally included only on Performa systems, but now are provided as part of the System 7.5 release for all systems in the new General Controls control panel device.
In addition, the following two items originally included only on Performa systems are now standard parts of System 7.5.
System 7.5 includes the optional installation package for QuickDraw GX. System 7.5 provides drivers for both QuickDraw GX and non-GX systems. The Chooser determines which environment is currently active and only displays printers that work in the current environment.
The following print drivers are included with System 7.5:
New Utilities and Desk Accessories are included in System 7.5. They help demonstrate new features available in System 7.5, such as Drag and Drop. The following are included on this CD:
When doing a clean install of System 7.5, the name stored in the System File as 'STR#' -16395 has been changed. (When installing System 7.5 over a previous version of system software, this change does not take place.) Instead of containing the explicit name of a particular CPU, the string contains " Macintosh", " Power Macintosh", or "Macintosh PowerBook". This change shows up in the Finder menu "About This Macintosh" as well as in various other code, such as the AppleTalk "responder" code, MacSNMP system MIB, etc. This change was implemented to allow greater flexibility in creating new Macintosh models for specific markets. The documentation in Inside Macintosh:Operating System Utilites on page 1-27 is now incorrect.
System 7.5 now includes a progress bar during boot time. Certain third party extensions try to put up dialog boxes at boot time. Calling InitWindows during boot time causes the progress bar dialog to disappear, yet the bar itself continues to be drawn. This misbehavior is due to extensions which try to do user interaction at boot time. Apple strongly recommends that you do not use the Window Manager or Dialog Manager until after the machine has completed booting. Use the Notification Manager to inform the user of information from within an extension, or consider rewriting your extension as an application and putting it in the startup items folder.
Apple Menu Options adds hierarchical menus to the Apple menu and adds three folders, Recent Applications, Recent Documents, and Recent Servers, to the Apple Menu.
The Recent Applications folder tracks all process launches except:
Finder
PrintMonitor
Desk Accessories
Processes in files of type 'INIT' or 'appe'
Background only processes
The Recent Documents folder is implemented by keeping track of basic system activity such as opening files, launching applications, and window manipulation. When one of these operations occurs, Apple Menu Options will try to find a match between an open file and a window title. Matches are only made between files and windows opened by the same process. A file name and window title are considered a match if the file name is substring of the window title either at the beginning of the window title, or at the end of the window title. For example, with an open file named "Document", the window titles "Document", "Document (WP)", or "(WP) Document" are considered matches. When a match is found, it is added to the Recent Documents folder.
When files are opened, a check is made for an existing window with a matching name. If a match is not found, the file is kept in a list of "unattached" files. When a window is opened or its title is changed, a check is made to see if an "unattached" file opened by the same process matches. Files opened by the Finder (except control panels), files opened by background-only applications, files opened by INITs, files opened by DAs, PrintMonitor files, clipboard files, and alias files are not tracked.
This means that if your application really wants to avoid having specific files added to the Recent Documents folder, it can use names for those files which won't be part of the window titles. For example, if your window title is going to be "Thesaurus" then a file name of "US Thesaurus" won't be a match and so it won't be added to the Recent Documents folder.
The Recent Servers folder is implemented by checking each successfully mounted volume to see if it is a server volume. Under System 7.5, only AppleShare volumes are tracked.
The acceleration which used to be provided by the 8*24 GC card control panel no longer works with System 7.5. The 8*24 GC card continues to function, but no acceleration is provided.
A new feature in System 7.5 allows you to load Macsbug without loading
extensions. As previously documented, holding down the shift key during the
boot process prevents all extensions (including Macsbug) from loading. Holding
down the option and shift keys together during the boot process allows Macsbug
to load, but prevents all extensions from loading.
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