Module addr 

Low-memory global variable addresses

Constants

ALERT_STAGE

AlertStage / ACount: stage of the last occurrence of an alert (2 bytes, INTEGER per IM:I I-423; MPW reads via #define GetAlertStage() (* (short*) 0x0A9A) per MTb 1992 22620). Holds 0..3 with stage = word+1. The Alert/StopAlert/NoteAlert/CautionAlert trio inspect this word to choose which 4-bit nibble of the ALRT template’s stages word to apply, then increment (capped at 3 — IM:I I-417). InitDialogs ($A97B) zeros it. ResetAlertStage and GetAlertStage are documented “[Not in ROM]” per IM:I I-422 — ResetAlertStage compiles to a direct CLR.W $0A9A.W store; GetAlertStage compiles to a direct word load. Read and write this address with read_word / write_word — using read_byte reads the high byte (always 0 for stages 0..3 on big-endian 68k) which is a subtle latent bug. Inside Macintosh Volume I, I-417 + I-423.

ANUMBER

ANumber: resource ID of the last alert that occurred (2 bytes, INTEGER). Written by Alert/StopAlert/NoteAlert/ CautionAlert ($A985..$A988) on each successful ALRT lookup. Inside Macintosh Volume I, I-423.

APPL_LIMIT

APP_L_ZONE

APP_PARM_HANDLE

AppParmHandle: handle to Finder launch information. The data begins with a message word and selected-file count word. Inside Macintosh Volume II, II-57; Files 1992, 1-58.

BUF_PTR

CURRENT_A5

CUR_APNAME

CUR_APREF_NUM

CUR_DIR_STORE

CUR_JT_OFFSET

CUR_STACK_BASE

DA_BEEPER

DABeeper: address of the current alert sound procedure (4 bytes, ProcPtr). Set by InitDialogs ($A97B) to the standard sound procedure; replaced by ErrorSound ($A98C) from its soundProc argument. NIL means “no sound (and no menu bar blink) at all” per IM:I I-411. Inside Macintosh Volume I, I-411.

DA_STRINGS

DAStrings: handles to the four ParamText strings (16 bytes = 4 × Handle). Substitutable into dialog and alert text via the ^0..^3 escapes at draw time. InitDialogs ($A97B) zeros all 4 entries (== “” empty strings); ParamText ($A98B) replaces each entry with a fresh handle to the caller’s Pascal string. Inside Macintosh Volume I, I-421 (DAStrings global array).

DEF_VCB_PTR

DLG_FONT

DlgFont: font number for subsequently created dialog and alert grafPorts. SetDAFont / SetDialogFont are documented glue routines; assembly code can also set this low-memory global directly. Inside Macintosh Volume I, I-412; Macintosh Toolbox Essentials 1992, p. 6-104.

DS_ERR_CODE

DSErrCode: current system error ID (word) written by SysError. Inside Macintosh Volume III (1985), low-memory globals table.

FCB_S_PTR

FS_Q_HDR

HEAP_END

J_CRSR_TASK

JCrsrTask: address of the cursor VBL task routine (ProcPtr). MPW Interfaces/AIncludes/LowMemEqu.a lists JCrsrTask EQU $8EE immediately after CrsrThresh and before the interrupt mouse globals.

KEY_MAP_LM

KeyMapLM: current keyboard bitmap, 4 longs / 16 bytes. Inside Macintosh Volume I, I-260 documents the GetKeys KeyMap as the current key state indexed by key code; MPW’s SysEqu.h names the low-memory mirror KeyMapLM at $0174.

MBAR_HEIGHT

MB_STATE

MEM_ERR

MemErr: current value of MemError (word). Inside Macintosh Volume IV, IV-80; low-memory table IV-246.

MEM_TOP

MENU_C_INFO

MenuCInfo: handle to the current menu color information table (4 bytes, MCTableHandle). Created by InitMenus and maintained by the Menu Color Manager traps: GetMCInfo ($AA61) returns a deep copy of the current table, SetMCInfo ($AA62) replaces the current table, DispMCInfo ($AA63) disposes a caller-supplied table, GetMCEntry ($AA64) returns a pointer into the live table, and SetMCEntries / DelMCEntries ($AA65 / $AA60) update or remove entries. Systemless HLE still does not auto-load ‘mctb’ resources, but it now stores a real live table here for API compatibility. Per IM:V V-247 + V-571 line 8688: MenuCInfo EQU $0D50. The Menu Color Manager was deprecated in System 7.5 by the Theme Manager (Macintosh Toolbox Essentials 1992 treats the routines as compatibility-only). Inside Macintosh Volume V, V-247..V-248 (Menu Color Manager routines) and V-571 (assembly globals table).

MENU_DISABLE

MenuDisable: menu ID + item number of the last menu item the cursor passed over while a menu was down (4 bytes, LongInt — high word = menuID, low word = itemNumber). Maintained by the standard menu definition procedure (‘MDEF’ 0) on each cursor-into-item transition, regardless of whether the item is enabled or disabled. Read by MenuChoice ($AA66) when the application’s MenuSelect / MenuKey returned zero, to surface “which disabled item did the user click?” for help/explanation UI. Per IM:V V-248 + MTb 1992 3-118 (the canonical EQU at IM:V V-571 line 8689: MenuDisable EQU $0B54). Systemless’s HLE reads this lowmem word directly in MenuChoice; it still does not synthesize the MDEF cursor-tracking writes that classic ROMs receive, so tests seed the value explicitly when they need a deterministic result. Inside Macintosh Volume V, V-248 (MenuChoice routine description) and V-571 (assembly globals table); Macintosh Toolbox Essentials 1992, 3-118..3-119 (MenuChoice canonical chapter).

MENU_FLASH

MMU32_BIT

MMU32Bit: TRUE when 32-bit addressing mode is in effect. Inside Macintosh: Memory 1992, p. 4-25 and low-memory table line 8838; also listed in Inside Macintosh Volume V, V-593.

MOUSE_LOC

MOUSE_LOC2

M_TEMP

RESUME_PROC

ResumeProc: address of the system error resume procedure (4 bytes, ProcPtr). Set by InitDialogs ($A97B) from its resumeProc parameter; read by the System Error Handler when a fatal system error occurs. Inside Macintosh Volume I, I-411 (and the Dialog Mgr globals summary table at I-432).

RND_SEED

ROM85

SCREEN_BITS

SCRN_BASE

SD_VOLUME

SdVolume: current speaker volume (1 byte, low-order three bits). Inside Macintosh Volume III, III-425 lists SdVolume at $0260 and describes it as the current speaker volume, with values 0..7.

SF_SAVE_DISK

SOUND_BASE

SoundBase: pointer to the free-form synthesizer’s main sound buffer. Inside Macintosh Volume III, III-425; Volume IV, IV-247 documents that programs should use this low-memory global rather than fixed hardware-dependent sound-buffer addresses.

SOUND_LEVEL

SoundLevel: amplitude in the Sound Driver’s 740-byte buffer (1 byte). Inside Macintosh Volume III, III-425.

SYS_ZONE

TE_SCRP_HANDLE

TEScrpHandle: handle to the TextEdit scrap (4 bytes, Handle). Per IM:I I-389 + assembly note at I-12598: the allocated relocatable block holding the cut/copied text bytes. TEInit ($A9CC) allocates a zero-length handle here on first call; TECopy / TECut / TEPaste resize the underlying block as needed. NIL if TEInit hasn’t run yet — defensive callers should check before dereferencing. Inside Macintosh Volume I, I-389 (TEScrpHandle global).

TE_SCRP_LENGTH

TEScrpLength: size of the TextEdit scrap in bytes (2-byte INTEGER). Per IM:I I-389 + I-390 + assembly note at I-12606: contains the byte count of the cut/copied text currently held in the TE-private scrap (separate from the shared desk scrap). Set to 0 by TEInit ($A9CC); rewritten by TECopy / TECut / TEPaste / TEFromScrap each time the scrap is touched. Apps that probe this from assembly to detect “is there text on the TE clipboard?” rely on it being correctly maintained. Inside Macintosh Volume I, I-389 (TEScrpLength global).

THE_PORT

THE_ZONE

TICKS

TIME

VCB_Q_HDR