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FILENAME: DOSMAC.DOC
DESCRIPTION: This file documents the macros implemented in the files IDOS.MAC
and MDOS.MAC. Note that the only difference between the two macro files is that
IDOS.MAC uses TASM's Ideal mode while MDOS.MAC uses TASM's Masm mode.
Terminate10Program
------------------
Function: Terminate a program without returning an errorlevel to DOS.
DOS Function: 00h
DOS Versions: 1, 2, 3
Input
cs - segment address of Program Segment Prefix(PSP)
Output
none
Registers modified: ah, flags
Syntax: Terminate10Program
ReadKBDEcho
-----------
Function: Reads a character from the keyboard or standard input device and
echoes it to the display. If a character isn't immediately available,
the DOS function waits for one.
DOS Function: 01h
DOS Versions: 1, 2, 3
Input
none
Output
al - character Registers modified: , flags
Syntax: ReadKBDEcho
CharacterOutput
---------------
Function: Outputs a character to the standard output device or to the active
video display.
DOS Function: 02h
DOS Versions: 1, 2, 3
Input
Character - byte value representing character to display
Output
none
Registers modified: ah, dl, flags
Syntax: CharacterOutput Character
AuxiliaryInput
--------------
Function: Reads the next character from the auxiliary input device.
DOS Function: 03h
DOS Versions: 1, 2, 3
Input
none
Output
al - byte value representing the character received
Registers modified: ax, flags
Syntax: AuxiliaryInput
AuxiliaryOutput
---------------
Function: Displays a character to the auxiliary output device.
DOS Function: 04h
DOS Versions: 1, 2, 3
Input
Character - byte value representing character to display
Output
none
Registers modified: ax, dl, flags
Syntax: AuxiliaryOutput
PrinterOutput
-------------
Function: Sends a character to the printer device.
DOS Function: 05h
DOS Versions: 1, 2, 3
Input
Character - value to send to the printer.
Output
none
Registers modified: ah, dl, flags
Syntax: PrinterOutput Character
ConsoleIO
---------
Function: Performs input/output from/to the console device.
DOS Function: 06h
DOS Versions: 1, 2, 3
Input
Function - Desired operation as defined below
Value Behavior
---------------------------------------------------
0-0FEh Display the character represented by Value
FFh Read a character
Output
Value = FF
A character is available
zero flag = clear
al - character
A character is not available
zero flag set
Registers modified: ax, dl, flags
Syntax: ConsoleIO Value
UnfilteredCharInput
-------------------
Function: Performs character input without checking for CTRL_BREAK. The
character input is not written to the display device.
DOS Function: 07h
DOS Versions: 1, 2, 3
Input
none
Output
al - The character read.
Registers modified: ax, flags
Syntax: UnfilteredCharInput
CharInputNoEcho
---------------
Function: Reads a character without echoing it to the screen.
DOS Function: 08h
DOS Versions: 1, 2, 3
Input
none
Output
al - character read
Registers modified: ax, flags
Syntax: CharInputNoEcho
WriteString
-----------
Function: Displays a $ terminated string to the string using.
DOS Function: 09h
DOS Versions: 1, 2, 3
Input
StringSeg - segment address of the string
StringOfs - offset address of string in StringSeg
Output
none
Registers modified: ax, dx, ds, Flags
Syntax: WriteString StringSeg, StringOfs
BufferedInput
-------------
Function: Reads a line from the standard input device and stores it in the
indicated buffer.
DOS Function: 0Ah
DOS Versions: 1, 2, 3
Input
StringSeg - segment address of the buffer
StringOfs - offset of the storage buffer
Output
none
Registers modified: ah, dx, ds, flags
Syntax: BufferedInput StringSeg, StringOfs
GetInputStatus
--------------
Function: Determines if a character is ready to be input.
DOS Function: 0Bh
DOS Versions: 1, 2, 3
Input
none
Output
al - 0 = no character available, FFh = character available
Registers modified: ax, flags
Syntax: GetInputStatus
ResetInputBuffer
----------------
Function: Resets the input buffer(i.e. clears its contents) and then waits for
a character. Note that if Function <> 0Ah, you do not need to provide
the StringSeg:StringOfs parameters.
DOS Function: 0Ch
DOS Versions: 1, 2, 3
Input
Function - number of the input function to invoke.
StringSeg - If Function = 0Ah, segment address of the buffer
StringOfs - offset of storage buffer
Output
Function = 0Ah
none
al - character read
Registers modified: ax, dx, ds, flags
Syntax: ResetInputBuffer Function, StringSeg, StringOfs
ResetDisk
---------
Function: Resets a disk. All buffers are flushed to the disk.
DOS Function: 0Dh
DOS Versions: 1, 2, 3
Input
none
Output
none
Registers modified: ah, flags
Syntax: ResetDisk
ChangeDrive
-----------
Function: Changes the default disk drive.
DOS Function: 0Eh
DOS Versions: 1, 2, 3
Input
Drive - Drive to change to
Output
al - number of logical drives in system
Registers modified: al, dl, Flags
Syntax: ChangeDrive Drive
OpenFCBFile
-----------
Function: Opens a file using an FCB and prepares it for I/O.
DOS Function: 0Fh
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: OpenFCBFile FCBSeg, FCBOfs
CloseFCBFile
------------
Function: Closes a file using an FCB.
DOS Function: 10h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: CloseFCBFile FCBSeg, FCBOfs
FindFirstFCB
------------
Function: Finds the first file in a directory that matches a given file
specification. File operations are performed using FCB's.
DOS Function: 11h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: FindFirstFCB FCBSeg, FCBOfs
FindNextFCB
-----------
Function: Finds the next entry in a directory matching the last file
specification given to FindFirstFCB.
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: FindNextFCB FCBSeg, FCBOfs
DeleteFCBFile
-------------
Function: Deletes a file defined in an FCB.
DOS Function: 13h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: DeleteFCBFile FCBSeg, FCBOfs
SequentialFCBRead
-----------------
Function: Performs a sequential read from a file opened using an FCB.
DOS Function: 14h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = read successful
1 = end of file
2 = segment wrap
3 = partial record read at eof
Registers modified: ax, dx, ds, flags
Syntax: SequentialFCBRead FCBSeg, FCBOfs
SequentialFCBWrite
------------------
Function: Performs a sequential write to a file opened using an FCB.
DOS Function: 15h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = write successful
1 = disk full
2 = segment wrap
Registers modified: ax, dx, ds, flags
Syntax: SequentialFCBWrite FCBSeg, FCBOfs
CreateFCBFile
-------------
Function: Creates a new file or truncates an existing file using an FCB.
DOS Function: 16h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: CreateFCBFile FCBSeg, FCBOfs
RenameFCBFile
-------------
Function: Renames a file(s) defined in an FCB.
DOS Function: 17h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: RenameFCBFile FCBSeg, FCBOfs
GetDrive
--------
Function: Returns the default disk drive.
DOS Function: 19h
DOS Versions: 1, 2, 3
Input
none
Output
al - drive code(0 = A, 1 = B, etc.)
Registers modified: al, Flags
Syntax: GetDrive
SetDTA
------
Function: Sets the current DTA address.
DOS Function: 1Ah
DOS Versions: 1, 2, 3
Input
StringSeg - segment address of new DTA
DTAOfs - offset in StringSeg of new DTA
Output
none
Registers modified: ax, dx, ds, Flags
Syntax: SetDTA DTASeg, DTAOfs
DefaultDiskAllocation
---------------------
Function: Gets the allocation information for the default disk drive.
DOS Function: 1Bh
DOS Versions: 1, 2, 3
Input
none
Output
al - sectors per cluster
ds:bx - address of the FAT id byte
cx - # of bytes per physical sector
dx - number of clusters on default drive
Registers modified: ax, bx, cx, dx, ds, flags
Syntax: DefaultDiskAllocation
DiskAllocation
--------------
Function: Gets the allocation information for a specific disk drive.
DOS Function: 1Ch
DOS Versions: 2, 3
Input
dl - drive id(0 = default, 1 = A, etc.)
Output
al - sectors per cluster
ds:bx - address of the FAT id byte
cx - # of bytes per physical sector
dx - number of clusters on default drive
Registers modified: ax, bx, cx, dx, ds, flags
Syntax: DiskAllocation Drive
RandomFCBRead
-------------
Function: Reads the indicated record from a file opened using an FCB.
DOS Function: 21h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = read successful
1 = end of file
2 = segment wrap
3 = partial record read at eof
Registers modified: ax, dx, ds, flags
Syntax: RandomFCBRead FCBSeg, FCBOfs
RandomFCBWrite
--------------
Function: Writes a record to the indicated position in a file opened using an
FCB.
DOS Function: 22h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = write successful
1 = disk full
2 = segment wrap
Registers modified: ax, dx, ds, flags
Syntax: RandomFCBWrite FCBSeg, FCBOfs
GetFCBFileSize
--------------
Function: Gets the number of records in a file opened using an FCB.
DOS Function: 23h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
al - 0 = operation successful, FFh = operation failed
Registers modified: ax, dx, ds, flags
Syntax: GetFCBFileSize FCBSeg, FCBOfs
SetFCBFileRecord
----------------
Function: Updates the record pointer field in the FCB to the current file
pointer position.
DOS Function: 24h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Output
Registers modified: ah, dx, ds, flags
Syntax: SetFCBFileRecord FCBSeg, FCBOfs
SetVector
---------
Function: Changes the indicated interrupt vector to the new vector defined in
VectorSeg:VectorOfs.
DOS Function: 25h
DOS Versions: 1, 2, 3
Input
Vector - Interrupt vector to modify
VectorSeg - Segment address of new interrupt handler
VectorOfs - Offset from VectorSeg of new handler
Output
none
Registers modified: ax, dx, ds, Flags
Syntax: SetVector Vector, VectorSeg, VectorOfs
CreatePSP
---------
Function: Creates a new Program Segment Prefix(PSP)
DOS Function: 26h
DOS Versions: 1, 2, 3
Input
PSPSeg - Segment address of new PSP
Output
none
Registers modified: ah, dx, flags
Syntax: CreatePSP PSPSeg
RandomFCBBlockRead
------------------
Function: Does a random read of one or more records from a file opened using an
FCB.
DOS Function: 27h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Count - Number of records to read
Output
al - 0 = read successful
1 = end of file
2 = segment wrap
3 = partial record read at eof
cx - actual # of records read from the file
Registers modified: ax, cx, dx, ds, flags
Syntax: RandomFCBBlockRead FCBSeg, FCBOfs, Count
RandomFCBBlockWrite
-------------------
Function: Performs a random write of the specified number of records to a file
opened using an FCB.
DOS Function: 28h
DOS Versions: 1, 2, 3
Input
FCBSeg - segment address of the File Control Block(FCB)
FCBOfs - offset of FCB
Count - Number of records to read
Output
al - 0 = write successful
1 = disk full
2 = segment wrap
cx - actual # of records written to the file
Registers modified: ax, cx, dx, ds, flags
Syntax: RandomFCBBlockWrite FCBSeg, FCBOfs, Count
ParseFCBFilename
----------------
Function: Parses a string representing a filename and fills in the appropriate
fields of an FCB.
DOS Function: 29h
DOS Versions: 1, 2, 3
Input
Flags - Flags that control parsing as defined below
FLAGS OPERATION
---------------------------------------------------------------------
Bit 3 = 1 Only if an extension is given in the indicated file spec
will the extension in the FCB will be modified.
= 0 Replace the FCB's current extension with the one in the
file spec or initialize the FCB to blanks.
Bit 2 = 1 Only if a filename is given in the indicated file spec
will the filename in the FCB will be modified.
= 0 Replace the FCB's current filename with the one in the
file spec or initialize the FCB to blanks.
Bit 1 = 1 Only if a drive is given in the indicated file spec will
the drive in the FCB will be modified.
= 0 Replace the FCB's current drive with the one in the file
spec or initialize the FCB to blanks.
Bit 0 = 1 Leading separators will be ignored.
= 0 Leading separators will not be ignored.
---------------------------------------------------------------------
FilenameSeg - Segment address of the string containing the filename
FilenameOfs - Offset of filename string
FCBSeg - Segment address of FCB
FCBOfs - Offset of FCB
Output
al - 0 = No wildcard characters
1 = Wildcard characters exist in the filename
FFh = Specified drive doesn't exist
ds:si - pointer to first byte position after the filename string
es:di - pointer to FCB
Registers modified: ax, di, si, ds, es, flags
Syntax: ParseFCBFilename Flags, FilenameSeg, FilenameOfs, FCBSeg, FCBOfs
GetDate
-------
Function: Gets the system date.
DOS Function: 2Ah
DOS Versions: 1, 2, 3
Input
none
Output
cx - year(1980 - 2099)
dh - month(1 - 12)
dl - day(1 - 31)
al - day of week(0 = Sunday, 1 = Monday, etc.) - Only on DOS 1.1
or later
Registers modified: ax, cx, dx, flags
Syntax: GetDate
SetDate
-------
Function: Sets the system date.
DOS Function: 2Bh
DOS Versions: 1, 2, 3
Input
Year - year(1980 - 2099)
Month - month(1 - 12)
Day - day(1 - 31)
Output
al - 0 = success, 0FFh = invalid date
Registers modified: ax, cx, dx, flags
Syntax: SetDate Year, Month, Day
GetTime
-------
Function: Gets the system time.
DOS Function: 2Ch
DOS Versions: 1, 2, 3
Input
none
Output
ch - hour(0 - 23)
cl - minutes(0 - 59)
dh - seconds(0 - 59)
dl - hundredths of a second(0 - 99)
Registers modified: ah, cx, dx, flags
Syntax: GetTime
SetTime
-------
Function: Sets the system time.
DOS Function: 2Dh
DOS Versions: 1, 2, 3
Input
Hour - hour(0 - 23)
Minute - minutes(0 - 59)
Second - seconds(0 - 59)
Hundredth - hundredths of a second(0 - 99)
Output
al - 0 = success, 0FFh - invalid time
Registers modified: ah, cx, dx, flags
Syntax: SetTime Hour, Minute, Second, Hundredth
SetVerifyFlag
-------------
Function: Sets the system verify flag to on or off.
DOS Function: 2Eh
DOS Versions: 1, 2, 3
Input
Flag - 0 = Turn off verify flag
- 1 = Turn the verify flag on
Output
none
Registers modified: ax, dl, flags
Syntax: SetVerifyFlag Flag
GetDTA
------
Function: Returns the address of the current DTA.
DOS Function: 2Fh
DOS Versions: 2, 3
Input
none
Output
es:bx - Far pointer to DTA
Registers modified: ah, bx, es, Flags
Syntax: GetDTA
GetDOSVersion
--------------
Function: Returns the DOS version.
DOS Function: 30h
DOS Services: 2, 3
Input
none
Output
ax - DOS version
Registers modified: ax, Flags
Syntax: GetDOSVersion
TSR
---
Function: Terminates a program but leaves it resident in memory.
DOS Function: 31h
DOS Versions: 2, 3
Input
Result - return code
Paragraphs - # of paragraphs to reserve for the program
Output
none
Registers modified: ax, dx, flags
Syntax: TSR Result, Paragraphs
GetSetBREAK
-----------
Functioni: Sets the CTR_BREAK checking flag. Note that if Mode = 0, you do not
need to provide the Value parameter.
DOS Function: 33h
DOS Versions: 2, 3
Input
Mode - 0 = Getting status of the flag
- 1 = Setting the status of the flag
Value - 0 = Turn CTRL-BREAK checking off
- 1 = Turn CTRL-BREAK checking on
Output
dl - 0 = if CTRL-BREAK checking off
- 1 = if CTRL-BREAK checking on
Registers modified: ax, dl, flags
Syntax: GetSetBREAK Mode, Value
GetVector
---------
Function: Returns the vector for a specified interrupt.
DOS Function: 35h
DOS Versions: 2, 3
Input
Interrupt - Which interrupt to return the vector of.
Output
es:bx - vector for the indicated interrupt
Registers modified: ax, bx, es, flags
Syntax: GetVector Interrupt
GetDiskSpace
------------
Function: Returns the amount of space available on the specified disk.
DOS Function: 36h
DOS Versions: 2, 3
Input
Disk - Which disk to check(0 = default, 1 = A, etc.)
Output
ax - sectors per cluster
FFFFh - if specified drive doesn't exist
bx - # of available clusters
cx - bytes per sector
dx - clusters per drive
Registers modified: ax, bx, cx, dx, flags
Syntax: GetDiskSpace Disk
GetSetCountryInfo
-----------------
Function: Gets or sets the current country information. Note that you can only
set the country information if running on DOS version 3.0 or later.
Note that if ShortCode < 255, then you do not need to provide the
LongCode parameter. If the LongCode parameter is provided, it will be
loaded into the apprpriate register regardless of the value of
ShortCode.
DOS Function: 38h
DOS Versions: 2, 3
Input
BufferSeg - Segment address of the buffer to store the info in.
BufferOfs - offset of the storage buffer.
ShortCode - < 255 = Specific country code < 255
0FFh = Country code >= 255 so use LongCode
LongCode - Country code >= 255
Output
bx - country code
ds:dx - pointer to the information buffer
Registers modified: ax, bx, dx, ds, flags
Syntax: GetSetCountryInfo BufferSeg, BufferOfs, ShortCode, LongCode
CreateDir
---------
Function: Creates a directory using the name pointed to by StringSeg:StringOfs.
DOS Function: 39h
DOS Versions: 2, 3
Input
StringSeg - Segment address of string containing directory name
StringOfs - Offset from StringSeg of directory name
Output
If function successful:
Carry flag - clear
If function failed
Carry flag - set
ax - error code:
3 - Path not found
5 - Access denied
Registers modified: ax, dx, ds, Flags
Syntax: CreateDir StringSeg, StringOfs
RemoveDir
---------
Function: Macro deletes the indicated directory.
DOS Function: 3Ah
DOS Versions: 2, 3
Input
StringSeg - Segment address of string containing directory name
StringOfs - Offset from StringSeg of directory name
Output
If function successful:
Carry flag - clear
If function failed
Carry flag - set
ax - error code:
3 - Path not found
5 - Access denied
6 - Current directory
16d - Current directory
Registers modified: ax, dx, ds, Flags
Syntax: RemoveDir StringSeg, StringOfs
ChangeDirectory
---------------
Function: Sets the current directory to the directory pointed to by
StringSeg:StringOfs.
DOS Function: 3Bh
DOS Versions: 2, 3
Input
StringSeg - segment address of ASCIIZ string
StringOfs - offset within StringSeg of directory name
Output
If function successful:
Carry flag - clear
If function failed
Carry flag - set
ax = error code:
3 - Path not found
Registers modified: ax, dx, ds, Flags
Syntax: ChangeDirectory StringSeg, StringOfs
CreateFile
----------
Function: Creates a new file or truncates an existing file to 0 bytes. A file
associated with the file is returned.
DOS Function: 3Ch
DOS Versions: 2, 3
Input
Attributes - File's attributes
StringSeg - Segment address of ASCIIZ file spec.
StringOfs - Offset within StringSeg of file spec.
Output
If function successful:
Carry flag - clear
ax - file handle
If function failed
Carry flag - set
ax - error code:
3 - Path not found
4 - No handle available
5 - Access denied
Registers modified: ax, cx, dx, ds, Flags
Syntax: CreateFile Attributes, StringSeg, StringOfs
OpenFile
--------
Function: Opens an exiting file and returns a file handle associated with the
file.
DOS Function: 3Dh
DOS Versions: 2, 3
Input
AccessMode - File access mode as defined below
BITS VALUE FUNCTION DOS VERSION
---- ----- ---------------------------- -----------
0-2 000 Read Access 2.0 & 3.0
001 Write Access 2.0 & 3.0
010 Read/Write Access 2.0 & 3.0
3 0 Reserved
4-6 000 Sharing mode, compatability mode 3.0
001 Sharing mode, read/write access 3.0
denied
010 Sharing mode, Write access denied 3.0
011 Sharing mode, Read access denied 3.0
100 Sharing mode, Full access permitted 3.0
7 0 Inheritance flag, File inherited 3.0
by child processes
1 Inheritance flag, File private to 3.0
current process
---------------------------------------------------------------
StringSeg - Segment address of ASCIIZ file spec.
StringOfs - Offset within StringSeg of file spec.
Output
If function successful:
Carry flag - clear
ax - file handle
If function failed
Carry flag - set
ax - error code:
1 - Function number invalid
2 - File not found
3 - Path not found or file doesn't exist
4 - No handle available
5 - Access denied
OCH - File access code invalid
Registers modified: ax, dx, ds, Flags
Syntax: OpenFile AccessMode, StringSeg, StringOfs
CloseFile
---------
Function: Closes a file associated with a file handle.
DOS Function: 3Eh
DOS Versions: 2, 3
Input
Handle - File handle of file to close
Output
If function successful:
Carry flag - clear
If function failed:
Carry flag - set
ax - error code:
6 - handle invalid or not open
Registers modified: ax, bx, Flags
Syntax: CloseFile Handle
ReadFile
--------
Function: Reads Count bytes from the file referenced by the file handle.
DOS Function: 3Fh
DOS Versions: 2, 3
Input
Handle - DOS file handle of file to read from
Count - # of bytes to read
StringSeg - Segment address of buffer to store data in
StringOfs - offset within StringSeg of storage buffer
Output
If function successful:
Carry flag - clear
ax - # of bytes read(0 if EOF)
If function failed
Carry flag - set
ax - error code:
5 - Access denied
6 - Invalid handle or file not open
Registers modified: ax, bx, cx, ds, Flags
Syntax: ReadFile Handle, Count, StringSeg, StringOfs
WriteFile
---------
Function: Writes Count bytes to the file referenced by the file handle.
DOS Function: 40h
DOS Versions: 2, 3
Input
Handle - DOS file handle of file to write to
Count - # of bytes to write
StringSeg - Segment address of buffer storing data
StringOfs - offset within StringSeg of storage buffer
Output
If function successful:
Carry flag - clear
ax - # of bytes read(0 if disk full)
If function failed
Carry flag - set
ax - error code:
5 - Access denied
6 - Invalid handle or file not open
Registers modified: ax, bx, cx, ds, Flags
Syntax: WriteFile Handle, Count, StringSeg, StringOfs
DeleteFile
----------
Function: Deletes the file pointed to by StringSeg:StringOfs.
DOS Function: 41h
DOS Versions: 2, 3
Input
StringSeg - segment address of the filename
StringOfs - offset from StringSeg of the filename
Output
If function successful:
Carry flag - clear
If function failed
Carry flag - set
ax - error code:
2 - File not found
5 - Access denied
Registers modified: ax, dx, ds, Flags
Syntax: DeleteFile StringSeg, StringOfs
MoveFilePtr
-----------
Function: Positions the file pointer in the file referenced by Handle.
DOS Function: 42h
DOS Versions: 2, 3
Input
Mode - Offset method as defined below
MODE FUNCTION
---- -----------------------------------------------------------
0 absolute byte offset from beginning of file(always unsigned
long integer)
1 byte offset from current location(signed long integer)
2 byte offset from end of file(signed long integer)
-------------------------------------------------------------------
Handle - File handle
OffsetHigh - Most significant word of offset
OffsetLow - Least significant word of offset
Output
If function successful:
Carry flag - clear
dx - most significant word of new pointer
ax - least significant word of new pointer
If function failed
Carry flag - set
ax - error code:
1 - Function number invalid
6 - Handle invalid or not open
Registers modified: ax, bx, cx, dx, Flags
Syntax: MoveFilePtr Mode, Handle, OffsetHigh, OffsetLow
GetSetAttributes
----------------
Function: Gets or sets the file attributes.
DOS Function: 43h
DOS Versions: 2, 3
Input
Mode
0 - Get file attributes
1 - Set file attributes
Attributes - New attributes or location to store file's current
attributes.
StringSeg - Segment address of the filename to check/modify
StringOfs - Offset within StringSeg of the filename
Output
If function successful:
Carry flag - clear
If al = 0 on call
cx - attribute
If function failed:
Carry flag - set
ax - error code:
1 - Function code invalid
2 - File not found
3 - Path not found or file doesn't exist
5 - Attribute can't be changed
Registers modified: ax, cx, dx, ds, Flags
Syntax: GetSetAttributes Mode, Attributes, StringSeg, StringOfs
IOCTL
-----
Function: Passes control information to a device driver. Note that you must
provide either the buffer address parameters or the device
information parameter but not both.
DOS Function: 44h
DOS Versions: 2, 3
Input
Function - What to do as defined below:
FUNCTION RESULT
-----------------------------------------------------------------------
00h Get device information
01h Set device information
02h Read from character device control channel to a buffer
03h Write to a character device control channel from a buffer
04h Read from block device control channel to a buffer
05h Write to a block device control channel from a buffer
06h Get the input status
07h Get output status
08h Check whether a block device is changable(DOS 3.0)
09h Check whether a drive is local or remote(DOS 3.1 &
Microsoft Networks)
0Ah Check whether a handle is local or remote(DOS 3.1 &
Microsoft Networks)
0Bh Change the sharing retry count
-----------------------------------------------------------------------
HandleDrive - Handle(functions 0, 1, 2, 3, 6, 7, 0Ah)
- Drive(0 = default, 1 = A, etc.)
Count - # of bytes to read/write
BufSegDevInfo - Represents Segment address of the input/output
buffer(functions 2-5)
- Represents device information(function 1).
BufferOfs - offset of the storage buffer(functions 2-5)
Output
Carry flag = clear - operation successful
ax - # of bytes read/written(functions 2-5)
al - 0 = not ready(functions 6-7)
- 1 = ready
ax - 0 = removable(function 8)
- 1 = fixed
dx - Device information(function 0)
Carry flag = set
ax - error code
1 = Invalid function number
4 = No handle available
5 = Access denied
6 = Invalid handle or device not open
0Dh = Invalid data
0Fh = Invalid drive number
Registers modified: ax, bx, cx, dx, ds, flags
Syntax: IOCTL Function, HandleDrive, Count, BufSegDevInfo, BufferOfs
DuplicateHandle
---------------
Function: Duplicates a file handle that is associated with an open file or
device.
DOS Function: 45h
DOS Versions: 2, 3
Input
Handle - the handle to duplicate
Output
carry flag = clear
ax - new file handle
carry flag = set
ax - error code
4 = No more file handles available
6 = Invalid handle or file not open
Registers modified: ax, bx, flags
Syntax: DuplicateHandle Handle
ForceDupHandle
--------------
Function: Takes two file handles and makes the second one equal to the first.
DOS Function: 46h
DOS Versions: 2, 3
Input
Original - Original file handle
Copy - Copy of the file handle
Output
carry flag = clear - operation successful
carry flag = set
ax - error code
4 = No more file handles available
6 = Invalid handle or file not open
Registers modified: ax, bx, cx, flags
Syntax: ForceDupHandle OriginalHandle, HandleCopy
GetCurrentDir
-------------
Function: Returns the current DOS directory on the indicated disk drive.
DOS Function: 47h
DOS Versions: 2, 3
Input
Drive - Disk drive(0 = default, 1 = A, etc.)
StringSeg - Segment address of 64-byte buffer to store directory
name in
StringOfs - Offset within StringSeg of the 64-byte buffer
Output
If function successful:
Carry flag - clear
The buffer is filled with the full path
If function failed
Carry flag - set
ax - error code:
0Fh - Invalid drive specification
Registers modified: ax, dl, si, ds, Flags
Syntax: GetCurrentDir Drive, StringSeg, StringOfs
AllocateMemory
--------------
Function: Allocates Paragraphs paragraphs of memory.
DOS Function: 48h
DOS Versions: 2, 3
Input
Paragraphs - # of paragraphs to allocate
Output
If function successful:
Carry flag - clear
ax - initial segment of allocated block
If function failed:
Carry flag - set
ax - error code:
7 - If memory control blocks destroyed
8 - If insufficient memory
bx - size of largest block available
Registers modified: ax, bx, Flags
Syntax: AllocateMemory Paragraphs
FreeMemory
----------
Function: Frees a DOS memory block.
DOS Function: 49h
DOS Versions: 2, 3
Input
BlockAddress - segment address of the memory block
Output
If function successful:
Carry flag - clear
If function failed:
Carry flag - set
ax - error code:
7 - If memory control blocks destroyed
8 - If insufficient memory
bx - size of largest block available
Registers modified: ax, es, Flags
Syntax: FreeMemory BlockAddress
ModifyMemory
------------
Function: Modifies A DOS memory blocks size.
DOS Function: 4Ah
DOS Versions: 2, 3
Input
Size - New block size in paragraphs
MemoryBlock - Segment address of current DOS memory block
Output
If function successful:
Carry flag - clear
If function failed
Carry flag - set
ax - error code:
7 - Memory control blocks destroyed
8 - Insufficient memory
9 - Incorrect segment in es
bx - maximum block size available
Registers modified: ax, bx, es, Flags
Syntax: ModifyMemory Size, MemoryBlock
Exec
----
Function: Runs another program or loads an overlay into memory.
DOS Function: 4Bh
DOS Versions: 2, 3
InputSyntax
Type - Indicates if the macro is running an application or loading an
overlay
ParmSeg - Segment address of parameter block
ParmOfs - Offset of parameter block
ProgramSeg - Segment address of program specification
ProgramOfs - Offset of program specification
Output
carry flag = clear - operation successful
all registers except cs and ip are destroyed
carry flag = set - operation not successful
ax - error code
1 = Invalid function
2 = Program not found
5 = Access denied
8 = Insufficient memory to run the program
0Ah = Invalid environment
0Bh = Invalid format
Registers modified: ax, bx, cx, dx, si, di, bp, sp, es, ds, ss, flags
Syntax: Exec Type, ParmSeg, ParmOfs, ProgramSeg, ProgramOfs
TerminateProgram
----------------
Function: Terminates the program. If running on DOS 1.0 or 1.1, use
Terminate10Program.
DOS Function: 4Ch
DOS Versions: 2, 3
Input
ErrorLevel - ErrorLevel to return to DOS
Output
None
Register modified
NA
Syntax
TerminateProgram ErrorLevel
GetReturnCode
-------------
Function: Gets the return code after an Exec.
DOS Function: 4Dh
DOS Versions: 2, 3
Input
none
Output
ah - exit type
0 = normal program termination
1 = program was terminated by a CTRL-C
2 = A critical device error terminated the program
3 = Function 31h terminated the program
al - return code of child process
Registers modified: ax, flags
Syntax: GetReturnCode
FindFirst
---------
Function: Finds the first entry in a directory that matches the given file
specification. The information about the file is then stored in the
current DTA.
DOS Function: 4Eh
DOS Services: 2, 3
Input
Attributes - Attributes to use in search for file
StringSeg - segment address of the filename
StringOfs - offset from StringSeg of the filename
Output
If function successful:
Carry flag - clear
DTA is initialized with file information
If function failed
Carry flag - set
ax - error code:
2 - Invalid path
12h - No matching entry found
Registers modified: ax, cx, dx, ds, Flags
Syntax: FindFirst Attributes, StringSeg, StringOfs
FindNext
-------
Function: Finds the next entry in a directory that matches the file
specification last given to FindNext. The information about the file
is then stored in the current DTA.
DOS Function: 4Fh
DOS Services: 2, 3
Input
none
Output
If function successful:
Carry flag - clear
DTA is initialized with file information
If function failed
Carry flag - set
ax - error code:
12h - No matching entry found
Registers modified: ax, Flags
Syntax: FindNext
GetVerifyFlag
-------------
Function: Gets the current value of the system's verify flag.
DOS Function: 54h
DOS Versions: 2, 3
Input
none
Output
al - current value
0 = verify off
1 = verify on
Registers modified: ax, flags
Syntax: GetVerifyFlag
RenameFile
----------
Function: Renames a file.
DOS Function: 56h
DOS Versions: 2, 3
Input
OrigSeg - Segment address of the string containing the original filename
OrigOfs - Offset of the string
NewSeg - Segment address of the new filename
NewOfs - Offset of the new filename string
Output
carry flag = clear - operation successful
carry flag = set - operation unsuccessful
ax - error code
2 = File not found
3 = File couldn't be found
5 = Access denied
11h = A different device
Registers modified: ax, dx, di, ds, es, flags
Syntax: RenameFile OrigSeg, OrigOfs, NewSeg, NewOfs
GetSetFileDateTime
------------------
Function: Will get or set a file's date and time. Note that you only need to
provide the Time and Date parameters when setting the file's Date and
Time.
DOS Function: 57h
DOS Versions: 2, 3
Input
GetSet - 0 = Get the file's date & time, 1 = Set them
Handle - File handle
Time - New time(GetSet = 1)
Date - New date(GetSet = 1)
Output
carry flag = clear - operation successful
carry flag = set - operation unsuccessful
ax - error code
1 - Invalid function
6 - Invalid file handle
Registers modified: ax, bx, cx, dx, flags
Syntax: GetSetFileDateTime GetSet, Handle, Time, Date
GetSetAllocationStrategy
------------------------
Function: Gets or sets DOS's memory allocation strategy.
DOS Function: 58h
DOS Versions: 3
Input
GetSet - 0 = get, 1 = set
Strategy - Code as defined below(GetSet = 1)
STRATEGY FUNCTION
------------------------------
0 First fit
1 Best fit
2 Last fit
Output
carry flag = clear - operation successful
carry flag = set - operation unsuccessful
ax - error code
1 = Invalid function
Registers modified: ax, bx, flags
Syntax: GetSetAllocationStrategy
GetExtendedErrors
-----------------
Function: Returns extended error information about a DOS error that just
occurrred.
DOS Function: 59h
DOS Versions: 3
Input
none
Output
ax - extended error code as defined below
CODE DESCRIPTION
----------------------------------------------------
1 Invalid function #
2 File not found
3 Path not found
4 Too many open files
5 Access denied
6 Invalid handle
7 Memory control blocks destroyed
8 Insufficient memory
9 Memory block address invalid
0Ah Environment invalid
0Bh Invalid format
0Ch Invalid access code
0Dh Invalid data
0Fh Invalid disk drive
10h Attempted to delete the current directory
11h Not the same device
12h No more files
13h Disk is write-protected
14h Unit unknown
15h Drive not ready
16h Unknown command
17h Data error(CRC value)
18h Bad request structure length
19h Seek error
1Ah Unknown medium type
1Bh Sector not found
1Ch Printer out of paper
1Dh Write fault
1Eh Read fault
1Fh General failure
20h Sharing violation
21h Lock violation
22h Disk change invalid
23h FCB unavailable
50h File already exists
52h Cannot create the directory
53h Int-24(critical error) failed
--------------------------------------------------------
bh - error class as defined below
CLASS DESCRIPTION
--------------------------------------------------------
1 Out of a resource
2 A temporary situation like a locked record
3 Authorization error
4 Internal system error
5 Hardware failure
6 System software failure
7 Application software error
8 File or item not found
9 Invalid format or type for file or item
0Ah File or item is interlocked
0Bh Wrong disk or bad disk
0Ch Any other error
--------------------------------------------------------
bl - recommended action as defined below
ACTION DESCRIPTION
---------------------------------------------------------------
1 Retry the operation a few times then prompt the user
2 Retry the operation with a small delay between retries,
then prompt the user.
3 Get input from user
4 Abort the application gracefully
5 Abort immediately
6 Ignore the error
7 Retry the operation after the user corrects the problem
----------------------------------------------------------------
ch - location of the error as defined below
LOCATION DESCRIPTION
----------------------------------------------------------------
1 Unknown
2 A block device like a disk or ram disk
3 Network related error
4 Serial device error
5 Memory related error
----------------------------------------------------------------
Registers modified: ax, bx, cx, flags
Syntax: GetExtendedErrors
CreateTemporaryFile
-------------------
Function: Creates a temporary file.
DOS Function: 5Ah
DOS Versions: 3
Input
Attribute - File attribute as defined below
ATTRIBUTE DESCRIPTION
-------------------------------------------
0 Normal file
1 Read-only
2 Hidden
4 System
-------------------------------------------
FilenameSeg - Segment address of filename string
FilenameOfs - Offset of filename string
Output
carry flag = clear - operation successful
ax - file handle
ds:dx - address of the filename string
carry flag = set - operation unsuccessful
ax - error code
3 = Path not found
5 = Access denied
Registers modified: ax, dx, ds, flags
Syntax: CreateTemporaryFile Attribute, FilenameSeg, FilenameOfs
CreateNewFile
-------------
Function: Creates a new file. If the specified file already exists, an error is
returned.
DOS Function: 5Bh
DOS Versions: 3
Input
Attribute - File attribute as defined below
ATTRIBUTE DESCRIPTION
-------------------------------------------
0 Normal file
1 Read-only
2 Hidden
4 System
-------------------------------------------
FilenameSeg - Segment address of filename string
FilenameOfs - Offset of filename string
Output
carry flag = clear - operation successful
ax - file handle
carry flag = set - operation unsuccessful
ax - error code
3 = Path not found
4 = No more file handles
5 = Access denied
50h = File already exists
Registers modified: ax, cx, dx, ds, flags
Syntax: CreateNewFile Attribute, FilenameSeg, FilenameOfs
ControlFileAccess
-----------------
Function: Locks or unlocks a record in a file on a networked system.
DOS Function: 5Ch
DOS Versions: 3
Input
LockUnlock - 0 = lock, 1 = unlock
Handle - File handle
OffsetHigh - High word of record offset
OffsetLow - Low word of record offset
LengthHigh - High word of record length
LengthLow - Low word of record length
Output
carry flag = cleared - operation successful
carry flag = set - operation unsuccessful
ax - error code
1 = Invalid function
6 = Invalid file handle
21h = All or part of the record is already locked
Registers modified: ax, bx, cx, dx, si, di, flags
Syntax: ControlFileAccess LockUnlock, Handle, OffsetHigh, OffsetLow, LengthHigh, LengthLow
GetMachineName
--------------
Function: Returns the local machine name on a network.
DOS Function: 5Eh Sub-Function: 00h
DOS Versions: 3
Input
BufferSeg - Segment address of the string buffer
BufferOfs - Offset of the buffer
Output
carry flag = clear - operation successful
ch = 0 - name not defined
> 0 - name defined
cl - NETBIOS name number(ch <> 0)
ds:dx - address of identifier(ch <> 0)
carry flag = set - operation unsuccessful
ax - error code
1 - Invalid function code
Registers modified: ax, cx, dx, ds, flags
Syntax: GetMachineName BufferSeg, BufferOfs
SetupPrinter
------------
Function: Sets up a printer attached to the network.
DOS Function: 5Eh Sub-Function: 02h
DOS Versions: 3
Input
BufferSeg - Segment address of the setup string
BufferOfs - Offset of the buffer
ListIndex - Redirection list index
StrLength - Length of the setup string
Output
carry flag = clear - operation successful
carry flag = set - operation unsuccessful
ax - error code
1 - Invalid function code
Registers modified: ax, bx, cx, si, ds, flags
Syntax: SetupPrinter BufferSeg, BufferOfs, ListIndex, StrLength
GetPrinterSetup
---------------
Function: Returns the local machine name on a network.
DOS Function: 5Eh Sub-Function: 03h
DOS Versions: 3
Input
BufferSeg - Segment address of the string buffer
BufferOfs - Offset of the buffer
Listindex - Redirection list index(Function = 2-3)
Output
carry flag = clear - operation successful
cx - length of the printer setup string
es:di - address of the buffer holding the setup string
carry flag = set - operation unsuccessful
ax - error code
1 - Invalid function code
Registers modified: ax, bx, cx, di, es, flags
Syntax: GetPrinterSetup BufferSeg, BufferOfs, ListIndex
GetListEntry
------------
Function: Gets a redirection list entry from the network system.
DOS Function: 5Fh Sub-function: 02h
DOS Versions: 3
Input
ListIndex - Redirection list index
DeviceSeg - Segment address of buffer to hold the device name
DeviceOfs - Offset of buffer
NetworkSeg - Segment address of buffer to hold the network's name
NetworkOfs - Offset of buffer
Output
carry flag = clear - operation successful
bh - device status flag(0 = valid device, 1 = invalid device)
bl - Device type(3 = printer, 4 = drive)
cx - Stored parameter
ds:si - address of device name
es:di - address of the network's name
carry flag = set - operation unsuccessful
ax - error code
1 = Invalid function
12h = No more files
Registers modified: ax, bx, cx, dx, bp, si, di, es, ds, flags
Syntax: GetListEntry ListIndex, DeviceSeg, DeviceOfs, NetworkSeg, NetworkOfs
GetListEntry
------------
Function: Redirects a device on a network.
DOS Function: 5Fh Sub-function: 03h
DOS Versions: 3
Input
Type - The device type as defined below
TYPE DESCRIPTION
------------------------------------------
3 Printer
4 Disk drive
------------------------------------------
Save - A parameter that needs to be saved for the caller
DeviceSeg - Segment address of buffer to hold the device name
DeviceOfs - Offset of buffer
NetworkSeg - Segment address of buffer to hold the network's name
NetworkOfs - Offset of buffer
Output
carry flag = clear - operation successful
carry flag = set - operation unsuccessful
ax - error code
1 = Invalid function
3 = Path not found
5 = Access denied
8 - Insufficient memory
Registers modified: ax, bx, cx, si, di, es, ds, flags
Syntax: GetListEntry Type, Save, DeviceSeg, DeviceOfs, NetworkSeg, NetworkOfs
GetListEntry
------------
Function: Redirects a device on a network.
DOS Function: 5Fh Sub-function: 04h
DOS Versions: 3
Input
DeviceSeg - Segment address of buffer to hold the device name
DeviceOfs - Offset of buffer
Output
carry flag = clear - operation successful
carry flag = set - operation unsuccessful
ax - error code
1 = Invalid function
0Fh - Redirection paused on server
Registers modified: ax, si, ds, flags
Syntax: GetListEntry DeviceSeg, DeviceOfs
GetPSPAddress
-------------
Function: Returns the address of the current PSP.
DOS Function: 62h
DOS Versions: 3
Input
none
Output
bx - Segment address of the Program Segment Prefix(PSP)
Registers modified: ah, bx, flags
Syntax: GetPSPAddress
LeadByteTable
-------------
Function: Returns the address of the system table of legal lead bytes or
gets/sets the value of the interim console flag.
DOS Function: 63h
DOS Versions: 2.25
Input
Function - The sub-function as defined below:
FUNCTION DESCRIPTION
-----------------------------------------------------------------
0 Get the address of the system lead byte table
1 Setting the value of the console flag
2 Getting the value of the console flag
-----------------------------------------------------------------
Console - Indicate if setting/getting the console flag(Function = 1)
Output
ds:si - Address of the lead byte table(Function = 0)
dl - Value of the console flag(Function = 2)
Registers modified: ax, dl, flags
Syntax: LeadByteTable Function, Console