ecm 2026-04ae

source/Interrupt List/INT 21 DOS Function Calls/INT 2100 DOS 1 TERMINATE PROGRAM.txt

@@ -13,6 +13,12 @@ Notes:	Microsoft recommends using INT 21/AH=4Ch for DOS 2+
 	  whatever cleanup it needs to do (restoring the INT 22,INT 23,INT 24
 	  vectors from the PSP assumed to be located at offset 0000h in the
 	  segment indicated by the stack copy of CS, etc.)
+	on MS-DOS v1 dirty FATs are written, the two or three INT vectors are
+	  copied to the IVT, and the resulting INT 22 vector is used along
+	  with the original (child / process that's terminating) user stack
+	  to return to the parent. the CS:IP and FL on the stack are not
+	  popped and the live FL contains IF=1 DF=0 and arithmetic status
+	  flags from XOR AX,AX (including ZF=1 CF=0).
 	if the PSP is its own parent, the process's memory is not freed; if
 	  INT 22 additionally points into the terminating program, the
 	  process is effectively NOT terminated

source/Interrupt List/INT 21 DOS Function Calls/INT 2126 DOS 1 CREATE NEW PROGRAM SEGMENT PREFIX.txt

@@ -38,7 +38,7 @@ Offset	Size	Description	(Table 01378)
  0Ah	DWORD	stored INT 22 termination address (Parent Return Address)
  0Eh	DWORD	stored INT 23 control-Break handler address
  12h	DWORD	DOS 1.1+ stored INT 24 critical error handler address
- 16h	WORD	segment of parent PSP (can be this PSP itself)
+ 16h	WORD	(presumed DOS 2+) parent PSP segment (can be this PSP itself)
  18h 20 BYTEs	DOS 2+ Job File Table, one byte per file handle, FFh = closed
 		(the JFT is known as Process Handle Table for lDOS)
  2Ch	WORD	DOS 2+ segment of environment for process (see #01379)
@@ -88,9 +88,6 @@ Notes:	in DOS v3+, the limit on simultaneously open files may be increased by
 	  Novell NetWare also uses values from FEh down to 80h or one more than
 	  FILES= (whichever is greater) to indicate remote files (except on
 	  OS/2, where is uses CFh down to 80h)
-	MS-DOS 5.00 incorrectly fills the FCB fields when loading a program
-	  high; the first FCB is empty and the second contains the first
-	  parameter
 	some DOS extenders place protected-mode values in various PSP fields
 	  such as the "parent" field, which can confuse PSP walkers.  Always
 	  check either for the CDh 20h signature or that the suspected PSP is
@@ -122,12 +119,16 @@ Notes:	in DOS v3+, the limit on simultaneously open files may be increased by
 	  vector, which may be relocated during processing of dconfig.sys
 	  or ldos.ini. FreeDOS happens to put the DOSDATA segment in this
 	  spot as well, but does not support relocating DOSDATA. (see also
-	  INT 2F/AX=1203h on DOSDATA segment details.)
+	  INT 31 on its use and INT 2F/AX=1203h on DOSDATA segment details.)
 BUGS:	When shelling out from the Borland Pascal 7.00 IDE, overly-long
 	  command lines will not be delimited by a 0Dh character, and the
 	  length byte is set to 80h!  A workaround is to always patch in a
 	  0Dh at the last position of the command line buffer before scanning
 	  the command line.
+	MS-DOS 5.00 incorrectly fills the FCB fields when loading a program
+	  high; the first FCB is empty and the second contains the first
+	  parameter
+	FreeDOS FreeCOM reportedly corrupts the second FCB (FreeCOM bug #185)
 
 Format of environment block:
 Offset	Size	Description	(Table 01379)

source/Interrupt List/INT 21 DOS Function Calls/INT 212B DOS 1 SET SYSTEM DATE.txt

@@ -15,6 +15,6 @@ Return: AL = status
 Notes:	DOS 3.3+ also sets CMOS clock; due to the limitations of the CLOCK$
 	  driver interface, the CMOS time is also updated to the current
 	  DOS time (which is the BIOS time-of-day clock with the default
-	  CLOCK$ driver)
+	  CLOCK$ driver, see MEM 0040h:006Ch and INT 08"IRQ0", INT 1C)
 SeeAlso: AH=2Ah,AH=2Dh,INT 1A/AH=05h
-
+

source/Interrupt List/INT 21 DOS Function Calls/INT 212D DOS 1 SET SYSTEM TIME.txt

@@ -17,4 +17,4 @@ Notes:	DOS 3.3+ also sets CMOS clock; due to the limitations of the CLOCK$
 	  driver interface, the CMOS date is also updated to the current
 	  DOS date
 SeeAlso: AH=2Bh"DOS",AH=2Ch,INT 1A/AH=01h,INT 1A/AH=03h,INT 1A/AH=FFh"AT&T"
-
+SeeAlso: INT 08"IRQ0",INT 1C,MEM 0040h:006Ch

source/Interrupt List/INT 21 DOS Function Calls/INT 2130 DOS 2 GET DOS VERSION.txt

@@ -25,14 +25,14 @@ Notes:	the OS/2 v1.x Compatibility Box returns major version 0Ah (10)
 	OS/2 Warp 3.0 Virtual DOS Machines report v20.30; Warp 4 VDMs report
 	  v20.40.
 	the Windows NT NTVDM DOS returns version 5.00, subject to SETVER
-	DOS 4.01 and 4.02 identify themselves as version 4.00; use
-	  INT 21/AH=87h to distinguish between the original European MS-DOS 4.0
-	  and the later PC-DOS 4.0x and MS-DOS 4.0x
+	MS-DOS 4.01 and 4.02 identify themselves as version 4.00
 	The MS-DOS v4.01 command.com displays the version as v4.01 by adding
 	  one to the minor version as returned from this function.
 	MS-DOS v4.00 was originally developed as v3.40, some references to
 	  this version number remained. The default contents of the special
 	  program list of MS-DOS v4.00 all are set up as returning v3.40
+	use INT 21/AH=87h to distinguish between multitasking/European MS-DOS
+	  4.00 and the v3.40 based developments PC-DOS 4.0x and MS-DOS 4.0x
 	IBM DOS 6.1 reports its version as 6.00; use the OEM number to
 	  distinguish between MS-DOS 6.00 and IBM DOS 6.1 (there was never an
 	  IBM DOS 6.0)
@@ -122,8 +122,7 @@ Notes:	the OS/2 v1.x Compatibility Box returns major version 0Ah (10)
 BUGS:	FreeDOS sources note that "32RTM won't like non-zero values" in CX
 SeeAlso: AX=3000h/BX=3000h,AX=3306h"DOS",AX=4452h,AH=87h,INT 15/AX=4900h
 SeeAlso: AH=20h"S/DOS",INT 2F/AX=122Fh,INT 2F/AX=4010h,INT 2F/AX=4A33h
-SeeAlso: INT 2F/AX=E002h
-SeeAlso: AX=33FCh
+SeeAlso: INT 2F/AX=E002h,AX=33FCh"FreeDOS",AX=33FFh
 
 (Table 01394)
 Values for DOS OEM number:
@@ -194,4 +193,3 @@ Notes:	'*' indicates an OEM release of MS-DOS, while '-' indicates an OEM
 	    Zenith DOS 2.x (uses Zenith disk mechanism, extra drives at G:)
 	    Zenith DOS 3.x (can be configured for Zenith or MS-DOS mechanism)
 	    Zenith DOS 3.3 PLUS (>32MB partitions similar to MS-DOS 4+)
-

source/Interrupt List/INT 21 DOS Function Calls/INT 213305 DOS 40 GET BOOT DRIVE.txt

@@ -14,4 +14,12 @@ Notes:	This function does not use any of the DOS-internal stacks and may
 	  drive letters sequentially to the other drives in the system
 	this call is supported by OS/2 Warp 3.0, but not earlier versions of
 	  OS/2; it is also supported by Novell DOS 7
+	the boot drive is the default drive during config processing
+	Enhanced DR-DOS and lDOS may set the boot drive to correspond to any
+	  on-disk file system/partition if their kernels are loaded from a
+	  given file system. if no exact partition match is found, then the
+	  first partition logged in on the same unit may be used.
+	other DOS versions reportedly only support using drive A: or C: (or
+	  possibly B:) as the boot drive; loading from an INT 13 unit >= 80h
+	  will then select drive C: as boot drive.
 SeeAlso: AX=335Fh

source/Interrupt List/INT 21 DOS Function Calls/INT 215D0B DOS 4x only internal GET DOS SWAPPABLE DATA AREAS.txt

@@ -37,8 +37,11 @@ SeeAlso: #01690
 Format of DOS 4.0-6.0 swappable data area:
 Offset	Size	Description	(Table 01690)
  -34	BYTE	printer echo flag (00h off, FFh active)
+ -33	BYTE	verify flag
+ -32	BYTE	CharCo (counts 0..63 for STATCHK call during text output)
  -31	BYTE	current switch character (ignored by DOS 5+)
  -30	BYTE	current memory allocation strategy (see AH=58h)
+ -29	BYTE	fShare (set by SHARE?)
  -28	BYTE	incremented on each INT 21/AX=5E01h call
  -27 16 BYTEs	machine name set by INT 21/AX=5E01h
  -11  5 WORDs	zero-terminated list of offsets which need to be patched to
@@ -74,7 +77,8 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
 ---remainder need only be swapped if in DOS---
  1Ah	WORD	value of AX on call to INT 21
 		Note:	does not contain correct value on functions 00h-0Ch,
-			  50h, 51h, 59h, or 62h			
+			  50h, 51h, 59h, or 62h. possibly also true of the
+			  functions 33h, 64h, 25h, 35h (user stack functions)
  1Ch	WORD	PSP segment for sharing/network (0000h = local)
  1Eh	WORD	network machine number for sharing/network (0000h = local)
  20h	WORD	first usable memory block found when allocating memory
@@ -91,8 +95,8 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
  2Fh	BYTE	padding (unused)
  30h	BYTE	day of month
  31h	BYTE	month
- 32h	WORD	year - 1980
- 34h	WORD	number of days since 01jan1980
+ 32h	WORD	year minus 1980
+ 34h	WORD	number of days since 1980-01-01
  36h	BYTE	day of week (0 = Sunday)
  37h	BYTE	flag: console swapped during read from device
  38h	BYTE	flag: safe to call INT 28 if nonzero
@@ -125,7 +129,7 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
 237h 11 BYTEs	wildcard destination specification for rename (FCB format)
 242h	BYTE	terminating NUL for above filespec
 243h	BYTE	padding???
-244h	WORD	destination starting sector (cluster???)
+244h	WORD	DESTSTART, REN destination start dir cluster (init from 2A2h)
 246h  5 BYTEs	extra space to allow a directory entry to be stored starting
 		  at offset 22Bh
 24Bh	BYTE	extended FCB file attributes
@@ -153,7 +157,7 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
 260h	DWORD	pointer to Drive Parameter Block for critical error invocation
 264h	DWORD	pointer to stack frame containing user registers on INT 21
 268h	WORD	stores SP across INT 24
-26Ah	DWORD	pointer to DOS Drive Parameter Block for ???
+26Ah	DWORD	pointer to current DOS Drive Parameter Block (see #01395)
 26Eh	WORD	segment of disk buffer
 270h	DWORD	saving partial cluster number
 274h	WORD	"sda_PREREAD" 00h if preread, 01h if optional
@@ -175,7 +179,7 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
 29Ah	WORD	last relative cluster within file being accessed
 29Ch	WORD	temp: absolute cluster number being accessed
 29Eh	DWORD	directory sector number
-2A2h	WORD	directory cluster number
+2A2h	WORD	DIRSTART, directory cluster number
 2A4h	DWORD	current relative sector number within file
 2A8h	DWORD	current sector number (number of previously written sectors)
 2ACh	WORD	current byte offset within sector
@@ -188,7 +192,7 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
 2BCh	WORD	next file cluster number
 2BEh	DWORD	number of bytes appended to file
 2C2h	DWORD	pointer to current work disk buffer
-2C6h	DWORD	pointer to working SFT
+2C6h	DWORD	pointer to working SFT "SFT of console swapped guy"
 2CAh	WORD	used by INT 21 dispatcher to store caller's BX
 2CCh	WORD	used by INT 21 dispatcher to store caller's DS
 2CEh	WORD	temporary storage while saving/restoring caller's registers
@@ -211,7 +215,7 @@ Notes:	the above data is not actually part of the SDA, and is much more likely
 2ECh	WORD	stores DS during call to [List-of-Lists + 37h]
 2EEh	WORD	temporary storage (various uses)
 2F0h	BYTE	storage for drive error
-2F1h	WORD	DOS 3.4 (European MS-DOS 4.00) bit flags
+2F1h	WORD	MS-DOS v3.40 (development branch that led to v4.00) bit flags
 2F3h	DWORD	pointer to user-supplied filename
 2F7h	DWORD	pointer to user-supplied rename destination filename
 2FBh	WORD	stores SS during call to [List-of-Lists + 37h] and INT 25,26 

source/Interrupt List/INT 2B DOS 2 RESERVED/INT 2B IBM ROMDOS v40.txt

@@ -1,5 +1,5 @@
 ----------------------------------------------------------------------------
- Unique ID: 2B
+ Unique ID: 2B-sort-as-2BIBMROM-DOS
   Category: D 	DOS kernel
       Flag: n/a
 ----------------------------------------------------------------------------
@@ -18,4 +18,4 @@ INT 2B - IBM ROM-DOS v4.0 - ???
 Notes:	function 03h is called by ROMSHELL.COM; if BX != 0, then the ES:DI from
 	  INT 2F/AX=1982h points at valid data
 SeeAlso: INT 2F/AX=1982h
-
+

source/Interrupt List/INT 2C DOS 2 RESERVED/INT 2C Cloaking CALL PROTECTEDMODE PASSALONG CHAIN.txt

@@ -1,5 +1,5 @@
 ----------------------------------------------------------------------------
- Unique ID: 2C
+ Unique ID: 2C-sort-as-2CCloaking
   Category: m 	memory management
       Flag: R 	available only in real or V86 mode
 ----------------------------------------------------------------------------
@@ -18,4 +18,4 @@ Notes:	when this interrupt is invoked in V86 mode, RM386 will invoke the first
 	this function was first introduced with RM386 (RAM-MAN/386) v6.00, the
 	  memory manager included in Helix Software's Netroom
 SeeAlso: INT 2C/AX=0009h,INT 2F/AX=4310h"Cloaking"
-
+

source/Interrupt List/INT 2C DOS 2 RESERVED/INT 2C RM386 v600 CLOAKING RESERVED FOR CLOAKED BIOS USE UNDER WINDOWS.txt

@@ -1,9 +1,9 @@
 ----------------------------------------------------------------------------
- Unique ID: 2C
+ Unique ID: 2C-sort-as-2CRM386
   Category: m 	memory management
       Flag: P 	available only in protected mode
 ----------------------------------------------------------------------------
 
 INT 2C P - RM386 v6.00 - CLOAKING - RESERVED FOR CLOAKED BIOS USE UNDER WINDOWS
 	AX = function (000Ch-001Fh)
-
+

source/Interrupt List/INT 2C DOS 2 RESERVED/INT 2C STARLITE architecture KERNEL API.txt

@@ -1,5 +1,5 @@
 ----------------------------------------------------------------------------
- Unique ID: 2C
+ Unique ID: 2C-sort-as-2CSTARLITE
   Category: O 	other operating systems
       Flag: n/a
 ----------------------------------------------------------------------------
@@ -9,4 +9,4 @@ Notes:	STARLITE is an architecture by General Software for a series of MS-DOS
 	  compatible operating systems (OEM DOS, NETWORK DOS, and SMP DOS) to
 	  be released in 1991.	The interrupt number is subject to change
 	  before the actual release.
-
+