Technical Notes

http://mcosre.sourceforge.net/docs/tech_notes.html
10/25/2007

M c O S R e

Technical Notes

"Inside Macintosh only mentions
the alternate screen buffer
in two places."

"When Hierarchical Filing System came
out, it provided a true folder structure."

SysVersion

The value of low-memory global variable SysVersion ($15A), and therefore the vaule returned by "sysv" Gestalt selector, is $0987 when running McOS Re (all versions).

Handles

A handle is a relocatable block of memory, referenced by an indirect pointer (an address of an address).

24-bit Memory Manager: flag bits of a master pointer

68k
leftmost byte 68k
long word PPC
(byte / 32-bit word)

7th bit 31st bit 0th bit locked

6th bit 30th bit 1st bit purgable

5th bit 29th bit 2nd bit resource

Example:

    BCLR        #7,(A3)             * unlock a handle in A3

[68k] $xx(A6) -> param


    LINK        A6,#x               * SP = A6+#x (note: #x is usually negative or 0)
    MOVEA.L     $0(A6),A2           * old A6
    MOVEA.L     $4(A6),A1           * return address
    MOVEA.L     $8(A6),A0           * param #last
    MOVE.L      $C(A6),D0           * param #last-1
    MOVE.L      $10(A6),D1          * param #last-2
    ...

Partition type strings
Names that begin with Apple_ are reserved for use by Apple Computer, Inc. Names shorter than 32 characters must be terminated with the NUL character.

Apple_partition_map partition contains a partition map

Apple_Driver partition contains a device driver

Apple_Driver43 partition contains a SCSI Manager 4.3 device driver

Apple_MFS partition uses the original flat Macintosh File System
(64K ROM version)

Apple_HFS partition uses the Hierarchical File System implemented in 128K
and later ROM versions

Apple_Unix_SVR2 partition uses the Unix file system

Apple_PRODOS partition uses the ProDOS file system

Apple_Free partition is unused

Apple_Scratch partition is empty

HFS+ Wrapper Volume
Wrapper Volume is a Mac OS Standard volume that wraps around the Mac OS Extended volume. It is required for backward compatibility and to startup from the Mac OS Extended volume.
Usual HFS+ Wrapper: software locked, 5 files, 1 directory, blessed dir id = 2 (root directory).
Boot Stages

Open Firmware stage (for OF-based systems only)

ROM stage (Boot ROM, ROM Toolbox, ROM resources)
[The PowerPC nanokernel and the 68k emulator are initialized during this stage.]

Boot blocks stage

HFS to HFS+ bootstrap stage (for HFS+ volumes only)

System file stage (System file code and resources)
[Current PowerPC nanokernel may be replaced with the System file's one at this stage.]

INIT stage (INITs, cdevs, RDEVs)

BootUp (Finder) launch

System Extensions
When the System boots, it opens your INIT file with OpenResFile, then it executes all of the INIT resources in that file. When it's done, it does a CloseResFile.
ANY INIT RESOURCES STILL OPEN FROM THAT FILE WILL GET RELEASED!
(This means that any code you have in the INIT will be marked as free on the heap.)

System 6: "INIT" #31 | additional INITs, cdevs,

System 7: "boot" #3 | RDEVs load code

INIT resources must be marked locked because INIT #31 does not lock them.