#Hfs file system goes with what system drivers
#Hfs file system goes with what system driver
#Hfs file system goes with what system software
#Hfs file system goes with what system code

A DA or driver indicates such a need by setting the dNeedTime bit in the flags word in its header.

#Hfs file system goes with what system drivers

SystemTask is a routine generally called in the main event loop of applications as a 'courtesy' to desk accessories and device drivers that need to have their Control routines entered at periodic intervals.

#Hfs file system goes with what system code

If some code in a Desk Accessory is time-consuming, can a call to SystemTask be placed in it? I have tried doing this with no apparent harm, but I'm concerned about re-entrancy problems.Р”Р„. The first 'count' pairs of size words and the first 'count' names are 'active' the remaining pairs of size words and name fields, if any, are unused. The first word of the resource is a count ranging up to 6 of the number of paper sizes that are 'active,' i.e., meaningful. N - number of active paper sizesР”В¦ pairs of words - vertical,horizontal paper size in 120ths of an inchР”В¦ Pascal-format strings - names of paper sizes A PREC resource specifies a selection of printer paper sizes. In an answer last month, the format of a PREC resource was given incorrectly. SFGetFile's volume purge routine does not discriminate among offline volumes which were mounted previously and those which were mounted while its dialog was active. A user searching for a file could possibly insert and eject a large number of disks. I'd guess the reason it does this is to avoid cluttering the VCB queue (list of online volumes) with disks that the user inserted and then ejected while the SFGetFile dialog box was up. One of the last things SFGetFile does after the user clicks Open or Cancel is to unmount any online volume that is not in a drive. I've noticed that sometimes when I put up an SFGetFile dialog box to allow the user to choose a file, after SFGetFile returns my DA does not show all the volumes that were there (in the VCB queue) prior to the SFGetFile. It also allows the user to change file attributes. I'm writing a desk accessory that shows information about all online volumes. In sum, DS is best used for program variables, while DC is best used for constants.

DC data is local to the segment in which it is assembled, and goes away if the segment is purged.Р”ВS storage does not use disk space within your application file DC storage does take up disk space. To alter DC data, its address must first be placed in a register, and then it can be written to using register indirect addressing, e.g.,Р”ВS storage is always resident while your application is running.

The assembler generates PC-relative addressing for references to DC data.Р”ВS global storage is not initialized when the application is loaded DC data is initialized.Р”ВS variables may be directly written with a MOVE instruction, e.g.,Р”ВC storage cannot be the direct destination of a MOVE instruction, because the 68000 does not allow the PC-relative addressing mode for the destination of a MOVE. The assembler will generate the value(s) given as arguments to DC, which stands for 'define constant.' DC provides a way to assemble arbitrary data instead of instructions. The DC directive allocates static space within your code segment, at the place where the directive appears. The linker also puts the total size of the global area into the CODE 0 resource, so than the Segment Loader can allocate sufficient space 'below A5' when the application is started. The linker calculates the offset of each variable declared with DS, and substitutes the offset where you use the symbolic name of the variable. The MDS Assembler DS directive reserves global variable storage that the program will address with an offset from the A5 register. Is it a question of style, or are there reasons of substance to use sometimes one, sometimes the other?Р”Р„. Loftus Becker of Hartford, CT asks how one should choose between DS and DC for data storage in assembly-language programs. In particular, don't be afraid to ask 'dumb' questions! But if I prefer that you not identify me, will you honor my request?Р”Р„. I know you like to give credit to readers who send questions.

#Hfs file system goes with what system software

MacР”В«y Steve Brecher, Software Supply, MacTutor Contributing Editor HFS File Structure Volume Number: 1 Issue Number: 12 Column Tag: Ask Prof. Educational Institution and Student Discounts.