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Summer 91 - Apple II Q& A

Apple II Q& A


Q Our Apple IIGS® TextEdit field created with NewControl2 appears to be redrawn within the TESetText call, but Apple II GS Toolbox Reference Volume 3 says controls won't be redrawn until the next update event. Is this a mistake in the documentation or in our logic?

A Internally, TextEdit uses control records for all TextEdit records. The main difference between control and noncontrol records is that the control defproc handles many of the standard TextEdit functions without requiring your application to do so. In the case of TESetText, though, TextEdit will always redraw the entire viewRect. This is a mistake in the manual.

Q We want to load $BC files from a folder when our program is launched. How do we ask the Apple II GS System Loader to discard these loaded files at application shutdown time? We tried using the main program's master ID from the Memory Manager, but the files are still not unloaded.

A The Loader is not designed to support more than one program with one user ID. It assumes that InitialLoad or InitialLoad2 will be called with distinct user IDs for each "program" to be controlled individually.

You need to get new user IDs (probably $1000 type) for each module you load, so that you can call UserShutDown on each of them individually when you need to. Don't dispose of the memory at the end; call UserShutDown on each of the IDs and the Loader will take care of the rest. If you're not quitting, you might want to shut them down in zombie state so that they don't have to be reloaded from disk if the memory is available. You can just pass $1000 as the user ID to InitialLoad and it will get a new ID for you and return it on the stack.

Remember that $BC auxiliary types are reserved and must be assigned by Apple Developer Technical Support.

Q How can I turn off the GS/OS file system cache, or keep it from writing to a disk while my file system optimizer is running?

A Altering volumes at the block level will confuse GS/OS ® , because the ProDOS® File System Translator (FST) keeps copies of file system structures that aren't in the cache. You need to use DWrite, although using DWrite instead of WRITE_BLOCK risks destroying the integrity of any open files on disk, such as the system resource file. If you use WRITE_BLOCK, you must close any open files, including the system resource file if you optimize the boot disk.

Once you start optimizing, don't make any calls that could directly or indirectly result in operating system calls--no DA access, no Font Manager calls, no loading tools, nothing. When you're done, GS/OS's internal volume control records (VCRs) will be completely invalid and you'll have to call OSShutDown.

Q When is it OK to make Apple II GS system service calls? I'd like to make calls such as MOVE_INFO from a driver that's executing asynchronously.

A It's OK to make system service calls in response to a GS/OS request, for example. Most of them require the OS environment, such as GS/OS's direct page, but MOVE_INFO, SET_SYS_SPEED, DYN_SLOT_ARBITER, and SIGNAL do not. When you're not in the GS/OS environment, make sure the proper language card bank of bank 1 is swapped in. Just JSLing there will put you into something that's not a system service call. You can either use the bank $E1 equivalents of MOVE_INFO, SET_SYS_SPEED, and DYN_SLOT_ARBITER, or you can make sure that the right $01 language card bank is enabled:

    lda >$E0C068
    lda >$E0C08B
    lda >$E0C08B
; Set up the registers and make your
; JSL  My_Favorite_SysSrv_Call
    lda >$E0C083
    lda >$E0C083
    sta >$E0C068

Q Do I have to write extra program code for my Apple II GS program to grow a resource?

A No, it's pretty straightforward. All you have to do to modify the content of any resource (including growing it) is to load the resource in, make any changes you want to the handle (such as change the data inside or call SetHandleSize to make it bigger), and then call MarkResourceChange. The Resource Manager updates the contents of your file when you call UpdateResourceFile. The Resource Manager recognizes the change in the size of the handle automatically.

Q The Apple IIGS does not seem to sort out equivalent devices on the Apple Desktop Bus TM (ADB) as the Macintosh does and as outlined in the ADB specification. We want multiple keyboard support, but the Apple IIGS ADB micro just begins reading blindly from addresses 2 and 3, assuming one keyboard and one mouse are attached. Is this information correct?

A The Apple IIGS does not do the same kind of dynamic device mapping and remapping that the Macintosh ADB Manager does. The "Apple Desktop Bus Tool Set" chapter of the Apple IIGS Toolbox Reference gives instructions on how to remap devices dynamically yourself. Essentially, you have two options:

  • You can leave the second keyboard address as 2, allowing input from multiple keyboards, but the keyboards' modifier key input will be mixed.
  • You can dynamically remap the keyboards in your program or in an INIT (although some forms of remapping require the user to press a key on the device to be remapped) and then a second keyboard will not appear as the standard keyboard--requiring all who use it to do their own ADB requests to get at the information entered from a second keyboard.

If you don't expect many developers to use a second keyboard, you might just choose to remap it inside any program that uses it. You could write an external library or functions that remap a second keyboard and read from it.

Q Where can I find documentation on how to recognize SCSI partitions, such as MS DOS partitions, from GS/OS?

A The documents you'll need are the GS/OS Reference (Addison-Wesley) and the GS/OS Device Driver Reference (APDA). You can recognize SCSI hard disk partitions programmatically by looking for a SCSI Hard Drive device type ($0005) and a forwardLink or headLink that's nonzero. This will give you all SCSI hard disk partitions, but it won't give you non-SCSI partitions, which have a different device type.

Bit 13 of the Device Characteristics word is for "Linked devices" like partitions, but the GS/OS Device Driver Reference says that bit applies to removable media, so not all third-party GS/OS drivers may set that bit for partitions (even though Apple's SCSI hard disk driver does).

Remember that GS/OS requires each partition to appear as a separate device, so there's no support for multiple partitions on one logical device.

Kudos to our readers who care enough to ask us terrific and well thought-out questions. The answers are supplied by our teams of technical gurus; our thanks to all. Special thanks to Matt Deatherage, C. K. Haun, Jim Luther, and Jim Mensch for the material in this Q & A column. *

Have more questions? Need more answers? Take a look at the Dev Tech Answers library on AppleLink (updated weekly) or at the Q & A stack on the Developer Essentials disc. *


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