ddl@husc6.UUCP (Dan Lanciani) (07/24/87)
This list is based on other postings, manuals, and some
research. I beleive it to be one of the more complete and useful
(at least to me since I use it...).
Dan Lanciani
ddl@harvard.*
-----------------------------------------------------------
INT 0 - DIVIDE ERROR
Automatically called at end of DIV or IDIV operation
that results in error. Normally set by DOS to display an error
message and abort the program.
-----------------------------------------------------------
INT 1 - SINGLE-STEP
Generated at end of each machine instruction if
TF bit in FLAGS is set. This is what makes the T command
of DEBUG work for single-stepping. Is not generated after
MOV to segment register or POP of segment register.
-----------------------------------------------------------
INT 2 - NMI (Non Maskable Interrupt)
Generated by NMI signal in hardware. Used in IBM for
memory parity error trapping.
-----------------------------------------------------------
INT 3 - 1-BYTE INTERRUPT
Generated by opcode 0CCh. Similar to 8080's RST
instruction. Generally used to set breakpoints for DEBUG.
-----------------------------------------------------------
INT 4 - OVERFLOW
Generated by INTO instruction if OF flag is set. If
flag is not set, INTO is effectively a NOP. Used to trap any
arithmetic errors when program is ready to handle them rather
than immediately when they occur.
-----------------------------------------------------------
INT 5 - Print-Screen Key
Automatically called by keyboard scan when print-
screen key is pressed. Normally executes routine to print
the screen, but may call any routine that can safely be
executed from inside the keyboard scanner.
Status and result byte at address 0050:0000.
-----------------------------------------------------------
INT 6 - XXX (IRET)
-----------------------------------------------------------
INT 7 - XXX (IRET)
-----------------------------------------------------------
INT 8 thru 0F - Vectored Hardware Lines
In IBM, these 8 interrupts are generated in
response to IRQ 0 through IRQ 7 (if enabled via port 21).
[Tandy 1000]
IRQ0 - timer interrupt
IRQ1 - keyboard interrupt
IRQ2 - EGA vertical retrace [fixed disk]
IRQ3 - serial port 2 (com2:)
IRQ4 - serial port 1 (com1:)
IRQ5 - fixed disk [60hz ram refresh]
IRQ6 - diskette interrupt
IRQ7 - PPI interrupt (lpt1:, lpt2:)
-----------------------------------------------------------
INT 10 - VIDEO - SET VIDEO MODE
AH = 0
AL =
0 = 40x25 B&W
1 = 40x25 COLOR
2 = 80x25 BW
3 = 80x25 COLOR
4 = 320x200 GRAPHICS, 4 COLOR
5 = 320x200 GRAPHICS, 4 GREY
6 = 640x200 GRAPHICS, B&W
7 = MONOCHROME GRAPHICS MODE
8 = 160x200 GRAPHICS, 16 COLOR
9 = 320x200 GRAPHICS, 16 COLOR
A = 640x200 GRAPHICS, 4 COLOR
Note: Modes 8-10 are only available on the PCjr (and Tandy 1000).
-----------------------------------------------------------
INT 10 - VIDEO - SET CURSOR CHARACTERISTICS
AH = 1
CH =
bits 5-6 = blink attribute
(00=normal, 01=invis., 11=fast)
bits 0-4 = start line for cursor in char. cell
CL =
bits 0-4 = end line for cursor in char. cell
-----------------------------------------------------------
INT 10 - VIDEO - SET CURSOR POSITION
AH = 2
DH,DL = ROW,COLUMN - 0,0 = UPPER LEFT
BH = PAGE NO. - 0 = GRAPHICS
-----------------------------------------------------------
INT 10 - VIDEO - READ CURSOR POSITION
AH = 3
BH = PAGE NO. - 0 = GRAPHICS
Return: DH,DL = ROW,COLUMN
CH,CL = CURSOR MODE,CURRENT SET
-----------------------------------------------------------
INT 10 - VIDEO - READ LIGHT PEN POSITION
AH = 4
Return: AH = 0: light pen switch not activated
AH = 1: light pen values in registers
DH = row of current position
DL = column of current position
CH = raster line (0-199)
BX = pixel column (0-319 or 0-639)
-----------------------------------------------------------
INT 10 - VIDEO - SELECT DISPLAY PAGE
AH = 5
AL =
0 - 7: NEW PAGE VALUE FOR MODES 0 & 1
0 - 3: NEW PAGE VALUE FOR MODES 2 & 3
80H: READ CRT/CPU PAGE REGISTERS
81H: SET CPU PAGE REGISTER TO VALUE IN BL
82H: SET CRT PAGE REGISTER TO VALUE IN BH
83H: SET BOTH DISPLAY REGISTERS
Return: BH = CRT PAGE REGISTER
BL = CPU PAGE REGISTER
-----------------------------------------------------------
INT 10 - VIDEO - SCROLL PAGE UP
AH = 6
AL = NO. OF LINES BLANKED AT BOTTOM OF PAGE
0 = BLANK WINDOW
BH = ATTRIBUTES TO BE USED ON BLANK LINE
WINDOW:
CH,CL = UPPER LEFT CORNER
DH,DL = LOWER RIGHT CORNER
-----------------------------------------------------------
INT 10 - VIDEO - SCROLL PAGE DOWN
AH = 7
AL = NO. OF LINES BLANKED AT TOP OF PAGE
0 = BLANK WINDOW
BH = ATTRIBUTES TO BE USED ON BLANK LINE
WINDOW:
CH,CL = UPPER LEFT CORNER
DH,DL = LOWER RIGHT CORNER
-----------------------------------------------------------
INT 10 - VIDEO - READ ATTRIBUTES/CHARACTER AT CURSOR POSITION
AH = 8
BH = DISPLAY PAGE
Return: AL = CHAR
AH = ATTRIBUTE OF CHAR - ALPHA MODE
-----------------------------------------------------------
INT 10 - VIDEO - WRITE ATTRIBUTES/CHARACTERS AT CURSOR POS
AH = 9
AL = CHARACTER
BH = DISPLAY PAGE - ALPHA MODE
BL = ATTRIBUTES OF CHAR
CX = NO. OF CHAR TO WRITE
-----------------------------------------------------------
INT 10 - VIDEO - WRITE CHARACTERS ONLY AT CURSOR POS
AH = 0AH
AL = CHARACTER
BH = DISPLAY PAGE - ALPHA MODE
BL = COLOR OF CHARACTER (GRAPHICS MODE)
CX = NO. OF CHAR TO WRITE
-----------------------------------------------------------
INT 10 - SET COLOR PALETTE
AH = 0BH
BH = PALETTE COLOR ID
BL = COLOR TO BE USED W/COLOR ID
-----------------------------------------------------------
INT 10 - WRITE DOT ON SCREEN
AH = 0CH
AL = COLOR OF DOT
DX = ROW (0000 - 00C7)
CX = COLUMN (0000 - 027F)
NOTE: VIDEO MODES 6 & 7 ONLY
-----------------------------------------------------------
INT 10 - READ DOT ON SCREEN
AH = 0DH
CX = COLUMN (0000 - 027F)
DX = ROW (0000 - 00C7)
Return: AL = COLOR READ
-----------------------------------------------------------
INT 10 - WRITE CHARACTER - ADVANCE CURSOR (TTY WRITE)
AH = 0EH
AL = CHARACTER
BL = FOREGROUND COLOR (VIDEO MODES 6 & 7 ONLY)
-----------------------------------------------------------
INT 10 - GET CURRENT VIDEO MODE
AH = 0FH
Return: AH = # OF COLUMNS ON SCREEN
AL = CURRENT VIDEO MODE
BH = CURRENT ACTIVE DISPLAY PAGE
-----------------------------------------------------------
INT 10 - SET PALETTE REGISTERS (PCjr AND TANDY 1000)
AH = 10H
AL = 0: SET PALETTE REGISTER
BL = PALETTE REGISTER TO SET
BH = COLOR VALUE TO STORE
AL = 1: SET BORDER COLOR REGISTER
BH = COLOR VALUE TO STORE
AL = 2: SET ALL PALETTE REGISTERS
ES:DX = POINTER TO 17-BYTE LIST
BYTES 0-15 = VALUES FOR PALETTE REGS. 0-15
BYTE 16 = VALUE FOR BORDER REGISTER
-----------------------------------------------------------
INT 10 - WRITE STRING, DON'T MOVE CURSOR (PC/AT ONLY)
AH = 13H
AL = 0
BL = ATTRIBUTE
BH = DISPLAY PAGE NUMBER
DX = STARTING CURSOR POSITION
CX = LENGTH OF STRING
ES:BP = POINTER TO START OF STRING
-----------------------------------------------------------
INT 10 - WRITE STRING, MOVE CURSOR AFTER STRING (PC/AT ONLY)
AH = 13H
AL = 1
BL = ATTRIBUTE
BH = DISPLAY PAGE NUMBER
DX = STARTING CURSOR POSITION
CX = LENGTH OF STRING
ES:BP = POINTER TO START OF STRING
-----------------------------------------------------------
INT 10 - WRITE STRING OF ALTERNATING CHARACTERS, ATTRIBUTES;
DON'T MOVE CURSOR (PC/AT ONLY)
AH = 13H
AL = 2
BH = DISPLAY PAGE NUMBER
DX = STARTING CURSOR POSITION
CX = LENGTH OF STRING
ES:BP = POINTER TO START OF STRING
-----------------------------------------------------------
INT 10 - WRITE STRING OF ALTERNATING CHARACTERS, ATTRIBUTES;
MOVE CURSOR (PC/AT ONLY)
AH = 13H
AL = 3
BH = DISPLAY PAGE NUMBER
DX = STARTING CURSOR POSITION
CX = LENGTH OF STRING
ES:BP = POINTER TO START OF STRING
-----------------------------------------------------------
INT 10 - GET VIDEO RAM ADDRESS
AH = 70H
Return: AX = SEGMENT ADDRESS OF THE FOLLOWING
[BX] = OFFSET ADDRESS OF GREEN PLANE
[CX] = SEGMENT ADDRESS OF GREEN PLANE
[DX] = SEGMENT ADDRESS OF RED/BLUE PLANE
(RED OFFSET = 0, BLUE OFFSET = 4000)
-----------------------------------------------------------
INT 10 - GET INCRAM ADDRESSES
AH = 71H
Return: AX = SEGMENT ADDRESS OF THE FOLLOWING
[BX] = SEGMENT ADDRESS OF INCRAM
[CX] = OFFSET ADDRESS OF INCRAM
-----------------------------------------------------------
INT 10 - SCROLL SCREEN RIGHT
AH = 72H
AL = NO. OF COLUMNS BLANKED AT LEFT OF PAGE
0 = BLANK WINDOW
BH = ATTRIBUTES TO BE USED ON BLANK COLUMNS
WINDOW:
CH,CL = UPPER LEFT CORNER
DH,DL = LOWER RIGHT CORNER
----------------------------------------------------------
INT 10 - SCROLL SCREEN LEFT
AH = 73H
AL = NO. OF COLUMNS BLANKED AT RIGHT OF PAGE
0 = BLANK WINDOW
BH = ATTRIBUTES TO BE USED ON BLANK COLUMNS
WINDOW:
CH,CL = UPPER LEFT CORNER
DH,DL = LOWER RIGHT CORNER
-----------------------------------------------------------
INT 11 - EQUIPMENT DETERMINATION
Return: AX = "equipment flag" bits
0 diskette installed
1 8087 present
2,3 always = 11
4,5 initial video mode
01 = 40x25 COLOR
10 = 80x25 COLOR
11 = 80X25 IBM monochrome
6,7 number of diskette drives (only if bit 0 = 1)
00 = 1, 01 = 2
8 0 = dma present, 1= no dma on system
9,10,11 number of RS232 cards
12 game I/O attached
13 serial printer installed (IBM-PCjr)
14,15 number of printers
-----------------------------------------------------------
INT 12 - MEMORY SIZE
Return: AX = NO. OF CONTIGUOUS 1K BLOCKS
-----------------------------------------------------------
INT 13 - RESET DISK SYSTEM
AH = 0
-----------------------------------------------------------
INT 13 - STATUS OF DISK SYSTEM
AH = 1
Return: AL = STATUS
01H = BAD COMMAND
02H = ADDRESS MARK NOT FOUND
03H = WRITE ATTEMPTED ON WRITE-PROTECTED DISK
04H = SECTOR NOT FOUND
06H = DISKETTE REMOVED
08H = DMA OVERRUN
09H = DMA ACROSS 64K BOUNDARY
10H = BAD CRC
20H = CONTROLLER FAILURE
40H = SEEK FAILED
80H = TIME OUT
-----------------------------------------------------------
INT 13 - READ SECTORS INTO MEMORY
AH = 2
AL = NO. OF SECTORS
CH = TRACK NO.
CL = SECTOR NO.
DH = HEAD NO.
DL = DRIVE NO.
ES:BX = ADDRESS OF BUFFER
Return: CF = SUCCESS/FAILURE SIGNAL
AH = STATUS (SEE ABOVE)
AL = NUMBER OF SECTORS READ
-----------------------------------------------------------
INT 13 - WRITES SECTORS FROM MEMORY
AH = 3
AL = NO. OF SECTORS
CH = TRACK NO.
CL = SECTOR NO.
DH = HEAD NO.
DL = DRIVE NO.
ES:BX = ADDRESS OF BUFFER
Return: CF = SUCCESS/FAILURE SIGNAL
AH = STATUS (SEE ABOVE)
AL = NUMBER OF SECTORS WRITTEN
-----------------------------------------------------------
INT 13 - VERIFIES SECTORS
AH = 4
AL = NO. OF SECTORS
CH = TRACK NO.
CL = SECTOR NO.
DH = HEAD NO.
DL = DRIVE NO.
Return: CF = SUCCESS/FAILURE SIGNAL
AH = STATUS (SEE ABOVE)
AL = NUMBER OF SECTORS VERIFIED
-----------------------------------------------------------
INT 13 - FORMAT DISKETTE TRACK
AH = 5
AL = NUMBER OF SECTORS
CH = TRACK NUMBER
CL = SECTOR NUMBER
DH = HEAD NUMBER
DL = DRIVE NUMBER
ES:BX = POINTER TO 4-BYTE ADDRESS FIELD
BYTE 1 = TRACK
BYTE 2 = HEAD
BYTE 3 = SECTOR
BYTE 4 = BYTES/SECTOR
Return: CF = SUCCESS/FAILURE SIGNAL
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - GET CURRENT DRIVE PARAMETERS (PC/AT ONLY)
AH = 8
DL = DRIVE NUMBER
Return: CF = SUCCESS/FAILURE FLAG
AH = STATUS CODE (SEE ABOVE)
DL = NUMBER OF DRIVES (?)
DH = MAX. NUMBER OF SIDES
CL = MAX. NUMBER OF SECTORS
CH = MAX. NUMBER OF TRACKS
-----------------------------------------------------------
INT 13 - INITIALIZE TWO FIXED DISK BASE TABLES (PC/AT ONLY)
AH = 9
Return: CF = SUCCESS/FAILURE FLAG
AH = STATUS CODE (SEE ABOVE)
INTERRUPT 41 POINTS TO TABLE FOR DRIVE 0
INTERRUPT 46 POINTS TO TABLE FOR DRIVE 1
-----------------------------------------------------------
INT 13 - READ LONG (PC/AT ONLY)
AH = 0AH
DL = DRIVE ID
DH = HEAD NUMBER
CH = CYLINDER NUMBER
CL = SECTOR NUMBER
ES:BX = POINTER TO BUFFER
Return: CF = SUCCESS/FAILURE FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - WRITE LONG (PC/AT ONLY)
AH = 0BH
DL = DRIVE ID
DH = HEAD NUMBER
CH = SECTOR NUMBER
ES:BX = POINTER TO BUFFER
Return: CF = SUCCESS/FAILURE FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - SEEK TO CYLINDER (PC/AT ONLY)
AH = 0CH
DL = DRIVE ID
DH = HEAD NUMBER
CH = SECTOR NUMBER
Return: CF = SUCCESS/FAILURE FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - ATLERNATE DISK RESET (PC/AT ONLY)
AH = 0DH
DL = DRIVE ID
Return: CF = SUCCESS/FAIL FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - TEST FOR DRIVE READY (PC/AT ONLY)
AH = 10H
DL = DRIVE ID
Return: CF = SUCCESS/FAIL FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - RECALIBRATE DRIVE (PC/AT ONLY)
AH = 11H
DL = DRIVE ID
Return: CF = SUCCESS/FAIL FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - CONTROLLER DIAGNOSTICS (PC/AT ONLY)
AH = 14H
Return: CF = SUCCESS/FAIL FLAG
AH = STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 13 - GET DISK TYPE (PC/AT ONLY)
AH = 15H
DL = DRIVE ID
Return: AH = DISK TYPE
0 = DISK NOT THERE
1 = DISKETTE, NO CHANGE DETECTION PRESENT
2 = DISKETTE, CHANGE DETECTION PRESENT
3 = FIXED DISK
CX,DX = NUMBER OF 512-BYTE SECTORS WHEN AH = 3
-----------------------------------------------------------
INT 13 - CHANGE OF DISK STATUS (PC/AT ONLY)
AH = 16H
Return: DL = DRIVE THAT HAD DISK CHANGE
AH = DISK CHANGE STATUS
00 = NO DISK CHANGE
01 = DISK CHANGED (6?)
-----------------------------------------------------------
INT 13 - SET DISK TYPE (PC/AT ONLY)
AH = 17H
AL = DISK TYPE
00 = NO DISK
01 = REGULAR DISK IN REGULAR DRIVE
02 = REGULAR DISK IN HIGH-CAP. DRIVE
03 = HIGH-CAP. DISK IN HIGH-CAP. DRIVE
DL = DRIVE ID
-----------------------------------------------------------
INT 14 - SERIAL I/O - INITIALIZE USART
AH = 0
AL = INITIALIZING PARAMETERS
7 - 6 - 5 4 - 3 2 1 - 0
-BAUD RATE- PARITY STOP WORD
BITS LENGTH
000 110 BD 00 NONE 0-1 10 - 7
001 150 BD 01 ODD 1-2 11 - 8
010 300 BD 11 EVEN
011 600 BD
100 1200 BD
101 2400 BD
110 4800 BD
111 9600 BD (4800 ON PCjr)
DX = PORT NUMBER
-----------------------------------------------------------
INT 14 - SERIAL I/O - TRANSMIT CHARACTER
AH = 1
AL = CHARACTER
DX = PORT NUMBER
Return: AH = RS-232 STATUS CODE BITS
0 = DATA READY
1 = OVERRUN ERROR
2 = PARITY ERROR
3 = FRAMING ERROR
4 = BREAK DETECTED
5 = TRANSMISSION BUFFER REG. EMPTY
6 = TRANSMISSION SHIFT REG. EMPTY
7 = TIME OUT
AL = MODEM STATUS BITS
0 = DELTA CLEAR-TO-SEND
1 = DELTA DATA-SET-READY
2 = TRAILING EDGE RING DETECTED
3 = CHANGE, RECEIVE LINE SIGNAL DETECTED
4 = CLEAR-TO-SEND
5 = DATA-SET-READY
6 = RING DETECTED
7 = RECEIVE LINE SIGNAL DETECTED
-----------------------------------------------------------
INT 14 - SERIAL I/O - RECEIVE CHARACTER
AH = 2
Return: AL = CHARACTER RECEIVED
AH = RS-232 STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 14 - SERIAL I/O - GET USART STATUS
AH = 3
Return: AH = RS-232 STATUS CODE (SEE ABOVE)
AL = MODEM STATUS CODE (SEE ABOVE)
-----------------------------------------------------------
INT 15 - TURN ON CASSETTE MOTOR
AH = 0
-----------------------------------------------------------
INT 15 - TURN OFF CASSETTE MOTOR
AH = 1
-----------------------------------------------------------
INT 15 - READ DATA BLOCKS FROM CASSETTE
AH = 2
CX = COUNT OF BYTES
ES:BX = POINTER TO DATA AREA
Return: CF = ERROR SIGNAL
DX = COUNT OF BYTES READ
ES:BX = POINTER PAST LAST BYTE READ
-----------------------------------------------------------
INT 15 - WRITE DATA BLOCKS TO CASSETTE
AH = 3
CX = COUNT OF BYTES TO WRITE
ES:BX = POINTER TO DATA AREA
Return: ES:BX = POINTER PAST LAST BYTE WRITTEN
-----------------------------------------------------------
INT 15 - DEVICE OPEN (PC/AT ONLY)
AH = 80
Return: BX = DEVICE ID
CX = PROCESS TYPE
-----------------------------------------------------------
INT 15 - DEVICE CLOSE (PC/AT ONLY)
AH = 81
Return: BX = DEVICE ID
CX = PROCESS TYPE
-----------------------------------------------------------
INT 15 - DEVICE PROGRAM TERMINATE (PC/AT ONLY)
AH = 82
Return: BX = DEVICE ID
-----------------------------------------------------------
INT 15 - EVENT WAIT (PC/AT ONLY)
AH = 83
AL = SUBSERVICE
0 = SET INTERVAL
1 = CANCEL
ES:BX = POINTER TO CALLER'S MEMORY
CX,DX = NUMBER OF MICROSECONDS TO WAIT
-----------------------------------------------------------
INT 15 - READ JOYSTICK SWITCH SETTINGS (PC/AT ONLY)
AH = 84
DX = 0
Return: AL = SWITCH SETTINGS
-----------------------------------------------------------
INT 15 - READ JOYSTICK INPUTS (PC/AT ONLY)
AH = 84
DX = 1
Return: AX = A(x) VALUE
BX = A(y) VALUE
CX = B(x) VALUE
DX = B(y) VALUE
-----------------------------------------------------------
INT 15 - SYSTEM REQUEST KEY PRESS (PC/AT ONLY)
AH = 85
Return: AL = 00 PRESS
AL = 01 BREAK
-----------------------------------------------------------
INT 15 - WAIT (PC/AT ONLY)
AH = 86
Return: CX,DX = NUMBER OF MICROSECONDS TO WAIT
-----------------------------------------------------------
INT 15 - EXTENDED MEMORY - BLOCK MOVE (PC/AT ONLY)
AH = 87
CX = NUMBER OF WORDS TO MOVE
ES:SI = POINTER TO TABLE
-----------------------------------------------------------
INT 15 - EXTENDED MEMORY - GET MEMORY SIZE (PC/AT ONLY)
AH = 88
Return: AX = MEMORY SIZE
-----------------------------------------------------------
INT 15 - SWITCH TO VIRTUAL MODE (PC/AT ONLY)
AH = 89
-----------------------------------------------------------
INT 15 - DEVICE BUSY LOOP (PC/AT ONLY)
AH = 90
AL = TYPE CODE
-----------------------------------------------------------
INT 15 - SET FLAG AND COMPLETE INTERRUPT
AH = 91
AL = TYPE CODE
-----------------------------------------------------------
INT 16 - KEYBOARD I/O - READ CHAR FROM BUFFER - WAIT IF EMPTY
AH = 0
Return: AH = SCAN CODE
AL = CHARACTER
-----------------------------------------------------------
INT 16 - KEYBOARD I/O - CHECK BUFFER - DO NOT CLEAR
AH = 1
Return: FLAG ZF = 0 = CHAR IN BUFFER
AH = SCAN CODE
AL = CHARACTER
FLAG ZF = 1 = NO CHAR IN BUFFER
-----------------------------------------------------------
INT 16 - KEYBOARD I/O - GET SHIFT STATUS
AH = 2
AL = SHIFT STATUS BITS
0 = RIGHT SHIFT KEY DEPRESSED
1 = LEFT SHIFT KEY DEPRESSED
2 = CTRL DEPRESSED
3 = ALT DEPRESSED
4 = SCROLL LOCK ACTIVE
5 = NUM LOCK ACTIVE
6 = CAPS LOCK ACTIVE
7 = INSERT STATE ACTIVE
-----------------------------------------------------------
INT 16 - KEYBOARD - SET DELAYS (PCjr ONLY)
AH = 3
AL = 0: RESET TYPEMATIC
AL = 1: INCREASE INITIAL DELAY
AL = 2: INCREASE CONTINUING DELAY
AL = 3: INCREASE BOTH DELAYS
AL = 4: TURN OFF TYPEMATIC
-----------------------------------------------------------
INT 16 - KEYBOARD - KEYCLICK (PCjr ONLY)
AH = 4
AL = 0: CLICK OFF
AL = 1: CLICK ON
-----------------------------------------------------------
INT 17 - CHARACTER TO PRINTER
AH = 0
AL = CHAR
Return: AH = STATUS BITS
0 = TIME OUT
1 = UNUSED
2 = UNUSED
3 = I/O ERROR
4 = SELECTED
5 = OUT OF PAPER
6 = ACKNOWLEDGE
7 = NOT BUSY
-----------------------------------------------------------
INT 17 - INITIALIZE PRINTER
AH = 1
Return: AH = STATUS (SEE ABOVE)
-----------------------------------------------------------
INT 17 - STATUS OF PRINTER
AH = 2
Return: AH = STATUS (SEE ABOVE)
-----------------------------------------------------------
INT 18 - TRANSFER TO ROM BASIC
CAUSES TRANSFER TO ROM-BASED BASIC (IBM-PC)
OFTEN REBOOTS A COMPATABLE
-----------------------------------------------------------
INT 19 - DISK BOOT
CAUSES REBOOT OF DISK SYSTEM (NO MEMORY TEST PERFORMED).
-----------------------------------------------------------
INT 1A - GET TIME OF DAY
AH = 0
Return: CX = high (most signif.) portion of clock count
DX = low (least signif.) portion of clock count
AL = 0 if clock was read or written (via AH=0,1)
withing the current 24-hour period
Otherwise, AL > 0
-----------------------------------------------------------
INT 1A - SET TIME OF DAY
AH = 1
CX = high (most signif.) portion of clock count
DX = low (least signif.) portion of clock count
-----------------------------------------------------------
INT 1A - READ REAL TIME CLOCK (PC/AT ONLY)
AH = 2
Return: CH = HOURS
CL = MINUTES
DH = SECONDS
-----------------------------------------------------------
INT 1A - SET REAL TIME CLOCK (PC/AT ONLY)
AH = 3
Return: CH = HOURS
CL = MINUTES
DH = SECONDS
DL = 1, IF DAYLIGHT SAVINGS; 0 IF STANDARD TIME
-----------------------------------------------------------
INT 1A - READ DATE FROM REAL TIME CLOCK (PC/AT ONLY)
AH = 4
Return: DL = DAY
DH = MONTH
CL = YEAR
CH = CENTURY (19 OR 20)
-----------------------------------------------------------
INT 1A - SET DATE IN REAL TIME CLOCK (PC/AT ONLY)
AH = 5
DL = DAY
DH = MONTH
CL = YEAR
CH = CENTURY (19 OR 20)
-----------------------------------------------------------
INT 1A - SET ALARM (PC/AT ONLY)
AH = 6
CH = HOURS
CL = MINUTES
DH = SECONDS
Return: INT. 4A = ADDRESS OF ALARM ROUTINE
-----------------------------------------------------------
INT 1A - RESET ALARM (PC/AT ONLY)
AH = 7
-----------------------------------------------------------
INT 1B - CTRL-BREAK KEY
This interrupt is called when the keyboard scanner of
the IBM machines detects CTRL and BREAK pressed at the same
time. It normally points to a simple IRET so that it does
nothing, but many programs change it to return a CTRL-C scan
code and thus invoke INT 23.
-----------------------------------------------------------
INT 1C - CLOCK TICK
This interrupt is called (in the IBM) at the end of
each time-update operation by the real-time clock routines. It
normally points to an IRET unless PRINT.COM has been installed.
-----------------------------------------------------------
INT 1D -> 4 6845 Video Init tables
-----------------------------------------------------------
INT 1E -> Diskette Params (BASE TABLE)
Default at f000:efc7
db step rate & head unload times
db head load time & DMA
db motor off time
db sector size (0->128, 1->256, 2->512, 3->1024)
db last sector number (8 or 9 typical)
db inter-sector gap size on read/write (42 typical)
db data transfer length (255 typical)
db inter-sector gap size on format (80 typical)
db sector fill on format (f6 typical)
db head-settle time ms (typical 25, 2.10->15)
db motor start-up time (1/8 secs) (typical 4, 2.10->2)
-----------------------------------------------------------
INT 1F -> Graphics Set 2
-----------------------------------------------------------
INT 20 - PROGRAM TERMINATION
RETURNS TO DOS
-----------------------------------------------------------
INT 21 - PROGRAM TERMINATION
AH = 00H
Same action as INT 20; returns to DOS.
-----------------------------------------------------------
INT 21 - KEYBOARD INPUT
AH = 01H
Return: AL = CHARACTER READ
-----------------------------------------------------------
INT 21 - DISPLAY OUTPUT
AH = 02H
DL = CHAR
-----------------------------------------------------------
INT 21 - AUX Input
AH = 03H
Return: AL = CHARACTER READ
-----------------------------------------------------------
INT 21 - AUX Output
AH = 04H
DL = CHAR
-----------------------------------------------------------
INT 21 - PRINTER OUTPUT
AH = 05H
DL = CHAR
-----------------------------------------------------------
INT 21 - DIRECT CONSOLE I/O - CHARACTER OUTPUT
AH = 06H
DL = CHAR
-----------------------------------------------------------
INT 21 - DIRECT CONSOLE I/O - CHARACTER INPUT
AH = 06H
DL = 0FFH
Return: FLAG ZF = SET = NO CHARACTER
CLEAR = CHARACTER RECIEVED
AL = CHARACTER
Character is echoed to STDOUT if received.
-----------------------------------------------------------
INT 21 - Direct STDIN Input, no echo
Reg AH = 07H
Same as Function 6 for input but char not echoed.
-----------------------------------------------------------
INT 21 - KEYBOARD INPUT - NO ECHO
AH = 08H
Return: AL = CHAR
-----------------------------------------------------------
INT 21 - PRINT STRING
AH = 09H
DS:DX = ADDRESS OF STRING TERMINATED WITH "$"
-----------------------------------------------------------
INT 21 - BUFFERED KEYBOARD INPUT
AH = 0AH
DS:DX = ADDRESS OF BUFFER
FIRST BYTE OF BUFFER MUST HAVE MAX LENGTH
ON RETURN SECOND BYTE HAS ACTUAL LENGTH
-----------------------------------------------------------
INT 21 - CHECK STANDARD INPUT STATUS
AH = 0BH
Return: AL =
FFH IF CHAR TYPED
00H IF NOT TYPED
-----------------------------------------------------------
INT 21 - Clear Keyboard Buffer
AH = 0CH
AL must be 1, 6, 7, 8, or 0aH.
Flushes all typeahead input, then executes function specified
by AL (by moving it to AH and repeating the INT 21 call).
-----------------------------------------------------------
INT 21 - Disk Reset
Reg AH = 0DH
Flushes all disk buffers.
-----------------------------------------------------------
INT 21 - SELECT DISK
AH = 0EH
DL = new default drive number (0 = A, 1 = B, etc.)
Return: AL = number of logical drives
-----------------------------------------------------------
INT 21 - OPEN DISK FILE
AH = 0FH
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
00 = FILE FOUND
FF = FILE NOT FOUND
-----------------------------------------------------------
INT 21 - CLOSE DISK FILE
AH = 10H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
-----------------------------------------------------------
INT 21 - Search First using FCB
AH = 11H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
00 = FILE FOUND
FF = FILE NOT FOUND
If file found, FCB is created at DTA address and
set up to OPEN or DELETE it.
-----------------------------------------------------------
INT 21 - Search Next using FCB
AH = 12H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
00 = FILE FOUND
FF = FILE NOT FOUND
If file found, FCB is created at DTA address and
set up to OPEN or DELETE it.
-----------------------------------------------------------
INT 21 - Delete File via FCB
AH = 13H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
00 = FILE FOUND
FF = FILE NOT FOUND
-----------------------------------------------------------
INT 21 - SEQUENTIAL DISK FILE READ
AH = 14H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
0 = SUCCESSFUL READ
1 = END OF FILE
2 = DATA TRANSFER AREA TOO SMALL
3 = PARTIAL RECORD, EOF
-----------------------------------------------------------
INT 21 - SEQUENTIAL DISK RECORD WRITE
AH = 15H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
0 = SUCCESSFUL WRITE
1 = DISKETTE FULL
2 = DATA TRANSFER AREA TOO SMALL
-----------------------------------------------------------
INT 21 - CREATE A DISK FILE
AH = 16H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
00 = SUCCESSFUL CREATION
FF = NO ROOM IN DIRECTORY
-----------------------------------------------------------
INT 21 - Rename File via FCB
AH = 17H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
FCB contains new name starting at byte 17H.
Return: AL =
00 = FILE FOUND
FF = FILE NOT FOUND
-----------------------------------------------------------
INT 21 - Internal - does nothing
AH = 18H XXX
Return: AL = 0
-----------------------------------------------------------
INT 21 - Default Disk Number
AH = 19H
Return: AL = current drive number (letter - 'A')
-----------------------------------------------------------
INT 21 - SET DISK TRANSFER AREA ADDRESS
AH = 1AH
DS = SEGMENT ADDRESS OF BUFFER
DX = OFFSET ADDRESS OF BUFFER
-----------------------------------------------------------
INT 21 - Default Drive Disk Size
AH = 1BH
Return: DS:BX points to FAT ID byte
DX = number of allocation units on disk
AL = number of sectors per AU
CX = number of bytes per sector
-----------------------------------------------------------
INT 21 - Specific Drive's Disk Size
AH = 1CH
DL = Drive Number to check
Return: DS:BX points to FAT ID byte
DX = number of allocation units on disk
AL = number of sectors per AU
CX = number of bytes per sector
-----------------------------------------------------------
INT 21 - Internal - does nothing
AH = 1DH XXX
Return: AL = 0
-----------------------------------------------------------
INT 21 - Internal - does nothing
AH = 1EH XXX
Return: AL = 0
-----------------------------------------------------------
INT 21 - Internal - GET DEFAULT DRIVE PARAMETER BLOCK
AH = 1FH
Return: AL =
00 = No Error
FF = Error
(DS:BX) = ADDRESS OF DRIVE PARAMETER BLOCK.
(THIS JUST INVOKES FUNCTION 32H WITH DL = 0)
-----------------------------------------------------------
INT 21 - Internal - does nothing
AH = 20H XXX
Return: AL = 0
-----------------------------------------------------------
INT 21 - RANDOM DISK RECORD READ
AH = 21H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
0 = SUCCESSFUL READ
1 = END OF FILE
2 = DATA TRANSFER AREA TOO SMALL
3 = PARTIAL RECORD, EOF
-----------------------------------------------------------
INT 21 - Random Disk Write
AH = 22H
Same setup as Random Read, but writes to disk
-----------------------------------------------------------
INT 21 - FILE SIZE
AH = 23H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
Return: AL =
00 = FILE FOUND
FF = FILE NOT FOUND
FCB SET TO NO. OF RECORDS
-----------------------------------------------------------
INT 21 - Set Random Record Field
AH = 24H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
FCB must be OPEN already
Return: Random Record Field of FCB is set to be
same as Current Block and Current Record.
-----------------------------------------------------------
INT 21 - Set Interrupt Vector
AH = 25H
AL = INT number
DS:DX = new vector to be used for specified INT
-----------------------------------------------------------
INT 21 - Create PSP
AH = 26H
DX = Segment number to set up PSP at
Current PSP is copied to specified segment
-----------------------------------------------------------
INT 21 - RANDOM BLOCK READ
AH = 27H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
CX = NO. OF RECORDS TO BE READ
Return: AL =
0 = SUCCESSFUL READ
1 = END OF FILE
2 = DATA TRANSFER AREA TOO SMALL
3 = PARTIAL RECORD, EOF
-----------------------------------------------------------
INT 21 - RANDOM BLOCK WRITE
AH = 28H
DS = SEGMENT ADDRESS OF FCB
DX = OFFSET ADDRESS OF FCB
CX = NO. OF RECORDS TO BE WRITTEN
Return: AL =
0 = SUCCESSFUL WRITE
1 = DISKETTE FULL
2 = DATA TRANSFER AREA TOO SMALL
-----------------------------------------------------------
INT 21 - Parse Filename
AH = 29H
DS:SI = POINTER TO STRING TO PARSE
ES:DI = POINTER TO MEMORY TO FILL WITH UNOPENED FCB
AL = BIT MASK TO CONTROL PARSING
0 = 0: PARSING STOPS IF FILE SEPERATOR FOUND
1: LEADING SEPERATOR IGNORED
1 = 0: DRIVE NUMNER IN FCB SET TO DEFAULT IF
STRING CONTAINS NO DRIVE NUMBER
1: DRIVE NUMBER IN FCB NOT CHANGED
2 = 0: FILENAME IN FCB SET TO BLANKS IF NO FILENAME IN STRING
1: FILENAME IN FCB NOT CHANGED IF STRING
DOES NOT CONTAIN A FILENAME
3 = 0: EXTENSION IN FCB SET TO BLANKS IF NO EXTENSION IN STRING
1: EXTENSION LEFT UNCHANGED
Return: AL = 00: NO WILDCARDS IN NAME OR EXTENSION
01: WILDCARDS APPEARED IN NAME OR EXTENSION
DS:SI = POINTER TO FIRST BYTE AFTER PARSED STRING
ES:DI = UNOPENED FCB
-----------------------------------------------------------
INT 21 - GET CURRENT DATE
AH = 2AH
Return: DL = DAY
DH = MONTH
CX = YEAR
AL = DAY OF THE WEEK (0=SUNDAY, 1=MONDAY, ETC.)
-----------------------------------------------------------
INT 21 - Set CURRENT DATE
AH = 2BH
DL = DAY
DH = MONTH
CX = YEAR
Return: AL = 0 if no error
AL = 0ffH if bad value sent to routine
-----------------------------------------------------------
INT 21 - GET CURRENT TIME
AH = 2CH
Return: CH = HOURS
CL = MINUTES
DH = SEC
DL = SEC/100
NOTE: TIME IS UPDATED EVERY 5/100 SECOND
-----------------------------------------------------------
INT 21 - Set CURRENT TIME
AH = 2DH
CH = HOURS
CL = MINUTES
DH = SEC
DL = SEC/100
Return: AL = 0 if no error
AL = 0ffH if bad value sent to routine
-----------------------------------------------------------
INT 21 - Set Verify Flag
AH = 2EH
DL = 0
AL = 1 if VERIFY on
AL = 0 if VERIFY off
-----------------------------------------------------------
INT 21 - Get Disk Transfer Area Address
AH = 2FH
Return: ES = SEGMENT address of DTA
BX = OFFSET address of DTA
-----------------------------------------------------------
INT 21 - Get DOS Version
AH = 30H
Return: AL = Major Version number
AH = Minor Version number
BH = OEM number
BL:CX = 24-bit user number
-----------------------------------------------------------
INT 21 - TERMINATE BUT STAY RESIDENT
AH = 31H
AL = EXIT CODE
DX = PROGRAM SIZE, IN PARAGRAPHS
-----------------------------------------------------------
INT 21 - Internal - GET DRIVE PARAMETER BLOCK
AH = 32H
DL = DRIVE NUMBER
0 = DEFAULT, 1 = A, ETC.
Return: AL = 0FFH IF INVALID DRIVE NUMBER, ELSE
DS:BX = ADDRESS OF DRIVE PARAMETER BLOCK.
STRUCTURE OF DOS DRIVE PARAMETER BLOCK:
DPBLOCK STRUCT ;OFFSET
DISK_OFFSET DB ? ; 0. DRIVE NUMBER (0 = A, ETC.)
UNIT_OFFSET DB ? ; 1. UNIT NUMBER WITHIN DEVICE DRIVER
SECTOR_SIZE DW ? ; 2. NUMBER OF BYTES PER SECTOR
MAX_CLUSTER DB ? ; 4. LARGEST SECTOR NUMBER IN CLUSTER
; ADD ONE FOR NUMBER OF SECTORS/CLUSTER
LOG2_SECTORS DB ? ; 5. LOG BASE TWO OF THE CLUSTER SIZE
RESERVED DW ? ; 6. NUMBER OF RESERVED (BOOT) SECTORS
FAT_COUNT DB ? ; 8. NUMBER OF COPIES OF THE FAT
ROOT_COUNT DW ? ; 9. NUMBER OF ROOT DIRECTORY ENTRIES
DATA_START DW ? ; 11. FIRST SECTOR OF DATA ON MEDIUM
MAX_NUMBER DW ? ; 13. LARGEST POSSIBLE CLUSTER NUMBER
; SUBTRACT ONE FOR NUMBER OF CLUSTERS
FAT_SECTORS DB ? ; 15. NUMBER OF SECTORS IN ONE FAT COPY
ROOT_START DW ? ; 16. FIRST SECTOR OF ROOT DIRECTORY
DEVICE_ADDR DD ? ; 18. CORRESPONDING DEVICE DRIVER ADDRESS
DESCRIPTOR DB ? ; 22. MEDIA DESCRIPTOR BYTE FOR MEDIUM
VALID_BYTE DB ? ; 23. 0FFH INDICATES BLOCK MUST BE REBUILT
NEXT_BLOCK DD ? ; 24. ADDRESS OF NEXT DEVICE BLOCK IN LIST
; FROM THIS POINT ON, DOS 3 DIFFERS FROM 2:
IF DOS2
DIR_START DW ? ; 28. STARTING CLUSTER OF CURRENT DIRECTORY
; ZERO INDICATES THE ROOT DIRECTORY
PATH_NAME DB 64 DUP (?)
; 30. ASCIIZ CURRENT DIRECTORY PATH STRING
ELSE DOS3
; ON MY XT, THIS WAS ALWAYS:
DW 0
DW 0FFFFH
ENDIF
DPBLOCK ENDS
-----------------------------------------------------------
INT 21 - Get or Set CONTROL-BREAK
AH = 33H
AL = 0 for Get or 1 for Put
DL = 0 for OFF or 1 for ON
Return: DL = 0 if BREAK=OFF or 1 if BREAK=ON
AL = FFH IF ERROR
-----------------------------------------------------------
INT 21 - Internal - Return CritSectFlag Pointer
AH = 34H
Return: ES:BX points to DOS "Critical Section Flag"
When byte pointed to is zero, DOS is supposed to be
safe to interrupt. NOT RELIABLE according to Chris Dunford.
Examination of DOS 2.10 code in this area
indicates that the byte immediately FOLLOWING this
"Critical Section Flag" must be 00 to permit the
PRINT.COM interrupt to be called. This suggests that
checking the WORD pointed to, rather than the BYTE,
might increase reliability of the test greatly.
-----------------------------------------------------------
INT 21 - Get Interrupt Vector
AH = 35H
AL = INT number
Return: ES = Segment address of INT vector
BX = Offset address of INT vector
-----------------------------------------------------------
INT 21 - DISK SPACE
AH = 36H
DL = DRIVE NUMBER (1-4)
Return: AX = ? (SIDES)
BX = ? (BLOCKS FREE)
CX = ? (BLOCK SIZE)
DX = ? (TOTAL BLOCKS)
NOTE: MULT AX x CX x BX for FREE SPACE ON DISK
MULT AX x CX x DX for TOTAL DISK SPACE
-----------------------------------------------------------
INT 21 - Internal - switchar/availdev
AH = 37H
AL =
0 Read switch character (returns current character in DL)
1 Set switch character (specify new character in DL)
2 Read device availability (as set by function AL=3)
3 Set device availability, where:
DL = 0 means /DEV/ must preceed device names
DL <> 0 means /DEV/ need not preceed device names
Return: DL = Switch character (if AL=0 or 1)
Device availability flag (if AL=2 or 3)
AL=0FFh means the value in AL was not in the range 0-3.
Functions 2 & 3 appear not to be implemented for dos 3.x
-----------------------------------------------------------
INT 21 - Get Country-Dependent Information
AH = 38H
Complex and differs between Dos 2.x and Dos 3.x
See Peter Norton "Programmer's Guide to the IBM PC", p. 305
-----------------------------------------------------------
INT 21 - CREATE A SUBDIRECTORY (MKDIR)
AH = 39H
DS = SEGMENT address of ASCIIZ pathname
DX = OFFSET address of ASCIIZ pathname
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - REMOVE A DIRECTORY ENTRY (RMDIR)
AH = 3AH
DS = SEGMENT address of ASCIIZ pathname
DX = OFFSET address of ASCIIZ pathname
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - CHANGE THE CURRENT DIRECTORY (CHDIR)
AH = 3BH
DS = SEGMENT address of ASCIIZ
DX = OFFSET address of ASCIIZ
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - CREATE A FILE WITH HANDLE (CREAT)
AH = 3CH
CX = ATTRIBUTES FOR FILE
DS = SEGMENT ADDRESS OF ASCIIZ
DX = OFFSET ADDRESS OF ASCIIZ
Return: Flag CF = 1 if error
AX = File Handle or Error Code
-----------------------------------------------------------
INT 21 - OPEN DISK FILE WITH HANDLE
AH = 3DH
AL = ACCESS CODE
0 = Read Only
1 = Write Only
2 = Read/Write
Options (3.x):
80H = no inheritance
10H = deny read/write
20H = deny write
30H = deny read
40H = deny none
DS = SEGMENT ADDRESS OF ASCIIZ
DX = OFFSET ADDRESS OF ASCIIZ
Return: Flag CF = 1 if error
AX = File Handle or Error Code
-----------------------------------------------------------
INT 21 - CLOSE A FILE WITH HANDLE
AH = 3EH
BX = FILE HANDLE
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - READ FROM FILE WITH HANDLE
AH = 3FH
BX = FILE HANDLE
CX = NO. OF BYTES TO READ
DS = SEGMENT ADDRESS OF BUFFER
DX = OFFSET ADDRESS OF BUFFER
Return: Flag CF = 1 if error
AX = Bytes Read or Error Code
-----------------------------------------------------------
INT 21 - WRITE TO FILE WITH HANDLE
AH = 40H
BX = FILE HANDLE
CX = NO. OF BYTES TO Write
DS = SEGMENT ADDRESS OF BUFFER
DX = OFFSET ADDRESS OF BUFFER
Return: Flag CF = 1 if error
AX = Bytes Read or Error Code
-----------------------------------------------------------
INT 21 - DELETE A FILE (UNLINK)
AH = 41H
DS = SEGMENT OF ASCIIZ TO DELETE
DX = OFFSET OF ASCIIZ TO DELETE
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - MOVE FILE READ/WRITE POINTER (LSEEK)
AH = 42H
AL = METHOD VALUE
0 = offset from beginning of file
1 = offset from present location
2 = offset from end of file
BX = FILE HANDLE
CX = BYTES OFFSET HIGH
DX = BYTES OFFSET LOW
Return: Flag CF = 1 if error
AX = Offset low word or Error Code
DX = Offset high word
-----------------------------------------------------------
INT 21 - GET/PUT FILE ATTRIBUTES (CHMOD)
AH = 43H
AL =
0 = GET FILE ATTRIBUTES
1 = PUT FILE ATTRIBUTES
CX = FILE ATTRIBUTES BITS ON PUT
0 = READ ONLY
1 = HIDDEN FILE
2 = SYSTEM FILE
3 = VOLUME LABEL
4 = SUBDIRECTORY
5 = WRITTEN SINCE BACKUP
DX = POINTER TO FILE ASCIIZ FILE NAME
Return: Flag CF = 1 if error
AX = Error Code if any
CX = FILE ATTRIBUTES ON GET
-----------------------------------------------------------
INT 21 - IOCTL
AH = 44H
AL =
0 = Get device information (DX)
1 = Set device information (DL, DH = 0)
DX BITS =
0 = console input device
1 = console output device
2 = null device
3 = clock device
5 = binary mode
6 = EOF
7 = is device
if not, EOF = 0 if channel has been written
bits 0-5 are block device number
12= network device
14= can process control strings (AL=2-5)
2 = Read CX bytes to DS:DX from BX control chan
3 = Write CX bytes from DS:DX from BX control chan
4 = as 2 but for drive BL
5 = as 3 but for drive BL
AX = number of bytes transfered
6 = Get input status
7 = Get output status
AX = FFH for ready or 00H for not ready
8 = Is block device BL changeable?
AX = 0 = yes
9 = Is logical device BL local?
DX (attribute word) bit 12 (1000H) = 0 = yes
10= Is handle BX local?
DX (attribute word) bit 15 (8000H) = 0 = yes
11= Change sharing retry count to DX (def 3), delay CX (def 1)
BX = file handle (or BL = drive number w/0 = default)
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Create Duplicate Handle (DUP)
AH = 45H
BX = file handle to duplicate
Return: Flag CF = 1 if error
AX = File handle or Error Code
-----------------------------------------------------------
INT 21 - Force Duplicate Handle (FORCDUP) (DUP2)
AH = 46H
BX = Existing file handle
CX = new file handle
Return: Flag CF = 1 if error
AX = File handle or Error Code
-----------------------------------------------------------
INT 21 - Get Current Directory
AH = 47H
DL = drive (0=default, 1=A, etc.)
DS:SI points to 64-byte buffer area
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Allocate Memory
AH = 48H
BX = number of 16-byte paragraphs desired
Return: Flag CF = 1 if error
AX = Segment of allocated memory or Error Code
BX = Maximum available on error
-----------------------------------------------------------
INT 21 - Free Memory
AH = 49H
ES = Segment address of area to be freed
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Adjust Block Size (SETBLOCK)
AH = 4AH
ES = Segment address of block to change
BX = New size in paragraphs
Return: Flag CF = 1 if error
AX = Error Code if any
BX = Maximum available on error
-----------------------------------------------------------
INT 21 - Load or Execute (EXEC)
AH = 4BH
AL =
0 = load and execute program
2 = load (Internal) but do not execute
3 = load overlay; do not create PSP
DS:DX = filename
ES:BX = parameter block
AL =
0 => word segment environment pointer
dword command line pointer
dword FCB 1
dword FCB 2
3 => word segment load address
word segment relocation factor
Return: Flag CF = 1 if error
AX = Error Code if any
struct exec {
unsigned exec_magic; /* 0x4d, 0x5a signature */
unsigned exec_isr; /* image size remainder (mod 512) */
unsigned exec_size; /* file size in pages (512) */
unsigned exec_nrel; /* number of relocation items */
unsigned exec_hsize; /* header size in paragraphs */
unsigned exec_min; /* minimum extra paragraphs */
unsigned exec_max; /* maximum extra paragraphs */
unsigned exec_ss; /* stack segment */
unsigned exec_sp; /* stack offset */
unsigned exec_cksum; /* word checksum of entire file */
unsigned exec_pc; /* initial pc */
unsigned exec_cs; /* code segment */
unsigned exec_orel; /* offset of relocation table */
unsigned exec_ovno; /* overlay number */
};
-----------------------------------------------------------
INT 21 - Quit With Exit Code (EXIT)
AH = 4CH
AL = exit code
-----------------------------------------------------------
INT 21 - GET EXIT CODE OF SUBPROGRAM (WAIT)
AH = 4DH
Return: AL = exit code of subprogram (FNs 31H or 4cH)
AH = circumstance which caused termination
0 = Terminate/abort
1 = Control-C
2 = Hard error
3 = Terminate and stay resident
-----------------------------------------------------------
INT 21 - Find First ASCIIZ (FIND FIRST)
AH = 4EH
CX = SEARCH ATTRIBUTES
DS:DX = POINTER TO ASCIIZ FILENAME (WITH ATTRIBUTES)
Return: Flag CF = 1 if error
AX = Error Code if any
(DTA) = data block
-----------------------------------------------------------
INT 21 - Find Next ASCIIZ (FIND NEXT)
AH = 4FH
Return: Flag CF = 1 if error
AX = Error Code if any
(DTA) = data block
-----------------------------------------------------------
INT 21 - Internal - Set PSP Segment
AH = 50H
BX = Segment address of new PSP
-----------------------------------------------------------
INT 21 - Internal - Get PSP Segment
AH = 51H
Return: BX = Current PSP Segment
struct psp {
char psp_int20[2]; /* 00h: exit */
unsigned psp_msize; /* 02h: memory size in paragraphs */
char psp_res0[1]; /* 04h: XXX (0) */
char psp_dos[5]; /* 05h: far call to dos */
int (*psp_term)(); /* 0ah: terminate address */
unsigned psp_tseg; /* 0ch: terminate segment */
int (*psp_break)(); /* 0eh: break address */
unsigned psp_bseg; /* 10h: break segment */
int (*psp_error)(); /* 12h: error address */
unsigned psp_eseg; /* 14h: error segment */
unsigned psp_ppsp; /* 16h: parent psp segment */
char psp_ofile[20]; /* 18h: open files, 0xff = unused */
unsigned psp_envp; /* 2ch: environment segment */
char psp_res2[4]; /* 2eh: XXX */
int psp_nfiles; /* 32h: max open files */
char *psp_aofile; /* 34h: ofile address */
unsigned psp_aoseg; /* 36h: ofile segment */
char psp_res3[24]; /* 38h: XXX */
char psp_int21[3]; /* 50h: int 21, far return */
char psp_res4[2]; /* 53h: XXX */
char psp_xfcb1[7]; /* 55h: FCB #1 extension */
char psp_fcb1[9]; /* 5ch: FCB #1 */
char psp_xfcb2[7]; /* 65h: FCB #2 extension */
char psp_fcb2[20]; /* 6ch: FCB #2 */
char psp_dma[128]; /* 80h: Command Tail */
};
-----------------------------------------------------------
INT 21 - Internal - Get Disk List
AH = 52H
Return: ES:BX points to DOS list of lists
List of Lists:
Bytes Value
0-3 Pointer to first DOS disk block (see func 36H)
4-7 Partially Unknown. Pointer to a device driver. Maybe first
resident driver?
8-B Partially Unknown. Pointer to a device driver. Maybe first
resident character device driver?
C-F Pointer to actual CON: device driver, whether installable
or resident
10-11 Unknown. 0200H. A byte/blocksize value???
12-15 Unknown. Pointer to current directory block????
16-19 Partially Undefined: Pointer to array of drive info:
51H bytes per drive, starting with A: ...
00-3F Current path as ASCIIZ, starting with 'x:\'
40-43 Unknown. I see zeros always
44 Unknown. Flags? I see 40H, except for
entry after last valid entry = 00H
45-48 Pointer to DOS Disk Block for this drive
49-4A Unknown. Current track or block? -1 if never
accessed.
4B-4E Unknown. I see -1 always
4F-52 Unknown. I see 2 always
1A-1D Unknown. Pointer to data area, maybe including cluster
allocation table?
1E-1F Unknown. I see zero always
20 Unknown. May be number of block devices.
21 Unknown. May be number of resident devices or ??? (5 always)
22 Beginning (not a pointer. The real beginning!) of NUL device
driver. This is the first device on DOS's linked list
of device drivers.
-----------------------------------------------------------
INT 21 - Internal - Translate BPB
AH = 53H
DS:SI points to BPB (Bios Parameter Block)
ES:BP points to area for DOS Disk Block
Translates BPB (Bios Parameter Block, see below)
into a DOS Disk Block (see function call 32h).
BPB
Bytes Value
0-1 Bytes/sector. Get from DDB bytes 2-3.
2 Sectors/cluster. Get from: (DDB byte 4) + 1
3-4 Reserved sectors. Get from: DDB bytes 6-7
5 Number of FATs. Get from: DDB byte 8
6-7 Number of root dir entries. Get from: DDB bytes 9-A
8-9 Total # of sectors. Get from:
((DDB bytes D-E) - 1) * (sectors per cluster (BPB byte 2))
+ (DDB Bytes B-C)
A Media descriptor byte. Get from: DDB byte 16
B-C Number of sectors/FAT. Get from: DDB byte F
-----------------------------------------------------------
INT 21 - Get Verify Flag
AH = 54H
Return: AL = 0 if flag OFF
AL = 1 if flag ON
-----------------------------------------------------------
INT 21 - Internal - Create PSP
AH = 55H
DX = Segment number to set up PSP at
Like FN 26H but creates "child" PSP rather
than copying existing one.
-----------------------------------------------------------
INT 21 - RENAME A FILE
AH = 56H
DS = SEGMENT OF ASCIIZ OLD NAME
DX = OFFSET OF ASCIIZ OLD NAME
ES = SEGMENT OF ASCIIZ NEW NAME
DI = OFFSET OF ASCIIZ NEW NAME
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Get/Put Date/Time
AH = 57H
AL = FUNCTION CODE
0 = GET DATE AND TIME
1 = SET DATE AND TIME
BX = FILE HANDLE
CX = TIME TO BE SET (IF AL = 1)
DX = DATE TO BE SET (IF AL = 1)
Return: Flag CF = 1 if error
AX = Error Code if any
CX = TIME OF LAST WRITE (IF AL = 0)
DX = DATE OF LAST WRITE (IF AL = 0)
-----------------------------------------------------------
INT 21 - Get/Set allocation strategy
AH = 58H
AL = FUNCTION CODE
0 = GET ALLOCATION STRATEGY
1 = SET ALLOCATION STRATEGY
BX = STRATEGY CODE (IF AL = 1)
0 = first fit
1 = best fit
2 = last fit
Return: Flag CF = 1 if error
AX = Strategy code or Error Code
-----------------------------------------------------------
INT 21 - GET EXTENDED ERROR CODE (DOS 3.X)
AH = 59H
BX = VERSION CODE (0000 FOR DOS 3.0)
Return: AX = EXTENDED ERROR CODE
BH = CLASS OF ERROR
BL = SUGGESTED ACTION CODE
CH = LOCUS (WHERE ERROR OCCURRED)
-----------------------------------------------------------
INT 21 - CREATE TMEPORARY FILE (DOS 3.x)
AH = 5AH
DS:DX = POINTER TO DIRECTORY PATH NAME
CX = FILE ATTRIBUTE
Return: Flag CF = 1 if error
AX = Error Code if any
DS:DX = PATH NAME
NOTE: THE FILE CREATED IS NOT TRULY "TEMPORARY". IT MUST BE
REMOVED BY THE USER.
-----------------------------------------------------------
INT 21 - CREATE NEW FILE (DOS 3.x)
AH = 5BH
DS:DX = POINTER TO DIRECTORY PATH NAME
CX = FILE ATTRIBUTE
Return: Flag CF = 1 if error
AX = Error Code if any
DS:DX = PATH NAME
NOTE: UNLIKE FUNCTION 3CH, FUNCTION 5BH WILL FAIL IF THE
ALREADY EXISTS.
-----------------------------------------------------------
INT 21 - LOCK/UNLOCK FILE ACCESS (DOS 3.x)
AH = 5CH
AL =
0 IF LOCK
1 IF UNLOCK
BX = FILE HANDLE
CX:DX = OFFSET TO LOCK
SI:DI = AMOUNT TO LOCK
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Internal - Unknown
AH = 5DH XXX
-----------------------------------------------------------
INT 21 - Get Machine Name (DOS 3.1 + Microsoft Networks)
AX = 5E00H
DS:DX -> buffer for ASCIIZ name
Return: Flag CF = 1 if error
AX = Error Code if any
CH = 0 if name not defined
CL = NETBIOS name number
-----------------------------------------------------------
INT 21 - Set Printer Setup (DOS 3.1 + Microsoft Networks)
AX = 5E02H
BX = Redirection list index
CX = length of setup string <= 64
DS:SI -> string buffer
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Get Printer Setup (DOS 3.1 + Microsoft Networks)
AX = 5E03H
BX = Redirection list index
ES:DI -> string buffer
Return: Flag CF = 1 if error
AX = Error Code if any
CX = length of setup string <= 64
-----------------------------------------------------------
INT 21 - Get Redirection List Entry (DOS 3.1 + Microsoft Networks)
AX = 5F02H
BX = Redirection list index
DS:DI -> 128 char local device name buffer
ES:DI -> 128 char network name buffer
Return: Flag CF = 1 if error
AX = Error Code if any
BX = Device status flag (BIT 0 = 0 if valid)
BL = device type
CX = stored param value
DX, BP destroyed
-----------------------------------------------------------
INT 21 - Redirect Device (DOS 3.1 + Microsoft Networks)
AX = 5F03H
BL = device type
03 = printer device
04 = file device
CX = stored param value
DS:SI -> source device name
ES:DI -> destination ASCIIZ network path + ASCIIZ password
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Cancel Redirection (DOS 3.1 + Microsoft Networks)
AX = 5F04H
DS:SI -> device name or network path
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 21 - Internal - Unknown
AH = 60H XXX
-----------------------------------------------------------
INT 21 - Internal - Unknown
AH = 61H XXX
-----------------------------------------------------------
INT 21 - GET PSP ADDRESS (DOS 3.x)
AH = 62H
Return: BX = SEGMENT ADDRESS OF PSP
-----------------------------------------------------------
INT 21 - GET LEAD BYTE TABLE (DOS 2.25 only)
AH = 63H
AL = SUBFUNCTION
0 = get system lead byte table
1 = set/clear interim console flag
2 = get interim console flag
DL = 1/0 to set/clear interim console flag
Return: DS:SI -> lead byte table (AL = 0)
DL = interim console flag (AL = 2)
-----------------------------------------------------------
INT 22 - TERMINATE ADDRESS
FAR (DWORD) address of routine to be executed
when program "returns to DOS". Should NOT ever be called.
-----------------------------------------------------------
INT 23 - CONTROL "C" EXIT ADDRESS
Automatically called from keyboard scanner when
CTRL-C or CTRL-BREAK is detected. Normally aborts program
and returns to DOS, but may be changed.
-----------------------------------------------------------
INT 24 - FATAL ERROR ABORT ADDRESS
Automatically called upon detection of unrecoverable
disk error. Normally prints "Abort, Retry, or Ignore?" message
and takes the reply, but may be changed if desired.
-----------------------------------------------------------
INT 25 - ABSOLUTE DISK READ
AL = Drive number (0=A, 1=B, etc)
DS:BX = Disk Transfer Address (buffer)
CX = Number of sectors to read
DX = First relative sector to read
Return: Flag CF = 1 if error
AX = Error Code if any
ORIGINAL FLAGS ON STACK!
-----------------------------------------------------------
INT 26 - ABSOLUTE DISK WRITE
AL = Drive number (0=A, 1=B, etc)
DS:BX = Disk Transfer Address (buffer)
CX = Number of sectors to write
DX = First relative sector to write
Return: Flag CF = 1 if error
AX = Error Code if any
ORIGINAL FLAGS ON STACK!
-----------------------------------------------------------
INT 27 - TERMINATE BUT STAY RESIDENT
CS = CURRENT PROGRAM SEGMENT
DX = LAST PROGRAM BYTE + 1
-----------------------------------------------------------
INT 28 - Internal - Keyboard Busy Loop
This interrupt is called from inside the "get input
from keyboard" routine in DOS, if and only if it is safe to use
INT 21 to access the disk at that time. It is used primarily by
the PRINT.COM routines, but any number of other routines could
be chained to it by saving the original vector, and calling it
with a FAR call (or just JMPing to it) at the end of the new
routine.
Until PRINT.COM installs its own routine, this
interrupt vector simply points to an IRET opcode.
-----------------------------------------------------------
INT 29 - Internal - Fast Putchar
This interrupt is called from the DOS output routines
if output is going to a device rather than a file, and the
device driver's attribute word has bit 3 (04H) set to "1".
-----------------------------------------------------------
INT 2A - Network Installation Check (Microsoft Networks)
AH = 00H
Return: AH <> 0 if installed
-----------------------------------------------------------
INT 2A - Check Direct I/O (Microsoft Networks)
AX = 0300H
DS:SI -> ASCIIZ disk device name
Return: CF == 0 if allowed
-----------------------------------------------------------
INT 2A - Execute NETBIOS (Microsoft Networks)
AH = 04H
AL = 0 for error retry, 1 for no retry
ES:BX -> NCB
Return: AX = 0 for no error
AH = 1, AL = error code
-----------------------------------------------------------
INT 2A - Get Network Resource Information (Microsoft Networks)
AX = 0500H
Return: AX = reserved
BX = # network names
CX = # commands
DX = # sessions
-----------------------------------------------------------
INT 2B - Internal routine for MSDOS (IRET) XXX
-----------------------------------------------------------
INT 2C - Internal routine for MSDOS (IRET) XXX
-----------------------------------------------------------
INT 2D - Internal routine for MSDOS (IRET) XXX
-----------------------------------------------------------
INT 2E - Internal - Execute Command
ES:SI -> counted CR-terminated command string
The top-level command.com executes the command; all
registers are destroyed as in exec.
-----------------------------------------------------------
INT 2F - Multiplexor - PRINT Installation Check
AX = 0100H
Return: AH =
FFH if installed
01H if not installed, not OK to install
00H if not installed, OK to install
-----------------------------------------------------------
INT 2F - Multiplexor - PRINT Submit file
AX = 0101H
DS:DX -> packet of one byte level and DWORD file pointer
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 2F - Multiplexor - PRINT Remove file
AX = 0102H
DS:DX -> file name (wildcards allowed)
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 2F - Multiplexor - PRINT Remove all files
AX = 0103H
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 2F - Multiplexor - PRINT Hold queue/Get status
AX = 0104H
Return: Flag CF = 1 if error
AX = Error Code if any
DX = Error count
DS:SI -> print queue (null-string terminated
list of 64-byte file names)
-----------------------------------------------------------
INT 2F - Multiplexor - PRINT Restart queue
AX = 0105H
Return: Flag CF = 1 if error
AX = Error Code if any
-----------------------------------------------------------
INT 2F - Multiplexor - ASSIGN Installation Check
AX = 0600H
Return: AH <> 0 if installed
-----------------------------------------------------------
INT 2F - Multiplexor - ASSIGN
AX = 0601H XXX
-----------------------------------------------------------
INT 2F - Multiplexor - MSDOS Internal
AH = 10H XXX
-----------------------------------------------------------
INT 2F - Multiplexor - MSDOS Internal
AH = 11H XXX
-----------------------------------------------------------
INT 2F - Multiplexor - MSDOS Internal
AH = 12H XXX
-----------------------------------------------------------
INT 2F - Multiplexor - APPEND Installation Check
AX = B700H
Return: AH <> 0 if installed
-----------------------------------------------------------
INT 2F - Multiplexor - APPEND
AX = B701H XXX
-----------------------------------------------------------
INT 2F - Multiplexor - Netowrk Program Installation Check
AX = B800H
Return: AH <> 0 if installed
-----------------------------------------------------------
INT 2F - Multiplexor - Get Current Post Address
AX = B803H
Return: ES:BX = post address
-----------------------------------------------------------
INT 2F - Multiplexor - Set New Post Address
AX = B804H
ES:BX = new post address
-----------------------------------------------------------
INT 33 - USED BY MICROSOFT MOUSE
-----------------------------------------------------------
INT 40 - Relocated (by fixed disk) Floppy Handler
-----------------------------------------------------------
INT 41 -> Fixed Disk Params
dw cylinders
db heads
dw 0
dw write pre-comp
db 0
db 0 "control byte"
db 0, 0, 0
dw landing zone
db sectors/track
db 0
-----------------------------------------------------------
INT 42 - Relocated (by EGA) Video Handler
-----------------------------------------------------------
INT 43 -> EGA Initialization Params
-----------------------------------------------------------
INT 44 -> EGA/PCjr fonts
-----------------------------------------------------------
INT 46 -> Secondary Fixed Disk Params
-----------------------------------------------------------
INT 48 - PCjr Cordless Keyboard Translation
-----------------------------------------------------------
INT 49 -> PCjr Non-keyboard Scan Code Translation Table
-----------------------------------------------------------
INT 4A - AT User Alarm
-----------------------------------------------------------
INT 70 thru 77 - AT Vectored Hardware Lines
IRQ8 - real-time clock
IRQ9 - LAN adapter 1 (to IRQ2)
IRQ10 - reserved
IRQ11 - reserved
IRQ12 - reserved
IRQ13 - 80287 error (to NMI)
IRQ14 - fixed disk
IRQ15 - reserved
-----------------------------------------------------------
INT 86 - Relocated (by NETBIOS) INT 18
-----------------------------------------------------------
INT 5C - NETBIOS interface
ES:BX -> Network Control Block
-----------------------------------------------------------
INT F8 - INTERVAL TIMER (10 MSEC)
-----------------------------------------------------------
INT FA - USART READY (RS-232C)
-----------------------------------------------------------
INT FB - USART Rx READY (keyboard)
-----------------------------------------------------------