IRQ - int table

Interrupt Function
0 Divide by zero
1 Single step
2 Non-maskable (NMI)
3 Breakpoint
4 Overflow trap
5 BOUND range exceeded (186,286,386)
6 Invalid opcode (186,286,386)
7 Coprocessor not available (286,386)
8 Double fault exception (286,386)
9 Coprocessor segment overrun (286,386)
A Invalid task state segment (286,386)
B Segment not present (286,386)
C Stack exception (286,386)
D General protection exception (286,386)
E Page fault (286,386)
F Reserved
10 Coprocessor error (286,386)
IRQ# Interrupt Function
IRQ0 8 timer (55ms intervals, 18.2 per second)
IRQ1 9 keyboard service required
IRQ2 A slave 8259 or EGA/VGA vertical retrace
IRQ8 70 real time clock (AT,XT286,PS50+)
IRQ9 71 software redirected to IRQ2 (AT,XT286,PS50+)
IRQ10 72 reserved (AT,XT286,PS50+)
IRQ11 73 reserved (AT,XT286,PS50+)
IRQ12 74 mouse interrupt (PS50+)
IRQ13 75 numeric coprocessor error (AT,XT286,PS50+)
IRQ14 76 fixed disk controller (AT,XT286,PS50+)
IRQ15 77 reserved (AT,XT286,PS50+)
IRQ3 B COM2 or COM4 service required, (COM3-COM8 on MCA PS/2)
IRQ4 C COM1 or COM3 service required
IRQ5 D fixed disk or data request from LPT2
IRQ6 E floppy disk service required
IRQ7 F data request from LPT1 (unreliable on IBM mono)
INT # Locus Function
0 CPU divide by zero
1 CPU single step
2 CPU non-maskable
3 CPU breakpoint
4 CPU overflow trap
5 BIOS print screen
6 CPU Invalid opcode (186,286,386)
7 CPU coprocessor not available (286,386)
8 IRQ0 timer (55ms intervals, 18.21590 per second)
9 IRQ1 keyboard service required (see INT 9)
A IRQ2 slave 8259 or EGA/VGA vertical retrace
B IRQ3 COM2 service required (PS/2 MCA COM3-COM8)
C IRQ4 COM1 service required
D IRQ5 fixed disk or data request from LPT2
E IRQ6 floppy disk service required
F IRQ7 data request from LPT1 (unreliable on IBM mono)
10 BIOS video (see INT 10)
11 BIOS Equipment determination (see <A HREF=“int_11.html”>INT 11</A>)
12 BIOS memory size (see <A HREF=“int_12.html”>INT 12</A>)
13 BIOS disk I/O service (see <A HREF=“int_13.html”>INT 13</A>)
14 BIOS serial communications (see <A HREF=“int_14.html”>INT 14</A>)
15 BIOS system services, cassette (see <A HREF=“int_15.html”>INT 15</A>)
16 BIOS keyboard services (see <A HREF=“int_16.html”>INT 16</A>)
17 BIOS parallel printer (see <A HREF=“int_17.html”>INT 17</A>)
18 BIOS ROM BASIC loader
19 BIOS bootstrap loader (unreliable, see <A HREF=“int_19.html”>INT 19</A>)
1A BIOS time of day (see <A HREF=“int_1a.html”>INT 1A</A>)
1B BIOS user defined ctrl-break handler (see <A HREF=“int_1b.html”>INT 1B</A>)
1C BIOS user defined clock tick handler (see <A HREF=“int_1c.html”>INT 1C</A>)
1D BIOS 6845 video parameter pointer
1E BIOS diskette parameter pointer (base table)
1F BIOS graphics character table
20 DOS general program termination
21 DOS function request services (see INT 21)
22 DOS terminate address (see <A HREF=“int_22.html”>INT 22</A>)
23 DOS control break termination address (see <A HREF=“int_23.html”>INT 23</A>)
24 DOS critical error handler (see <A HREF=“int_24.html”>INT 24</A>)
25 DOS absolute disk read (see <A HREF=“int_25.html”>INT 25</A>)
26 DOS absolute disk write (see <A HREF=“int_26.html”>INT 26</A>)
27 DOS terminate and stay resident (see <A HREF=“int_27.html”>INT 27</A>)
28 DOS idle loop, issued by DOS when idle (see <A HREF=“int_28.html”>INT 28</A>)
29 DOS fast TTY console I/O (see <A HREF=“int_29.html”>INT 29</A>)
2A DOS critical section and NETBIOS (see <A HREF=“int_2a.html”>INT 2A</A>)
2B DOS internal, simple <A HREF=“iret.html”>IRET</A> in DOS 2.0-5.0
2C DOS internal, simple IRET in DOS 2.0-5.0
2D DOS internal, simple IRET in DOS 2.0-5.0
2E DOS exec command from base level command interpreter (see <A HREF=“int_2e.html”>INT 2E</A>)
2F DOS multiplexer (see <A HREF=“int_2f.html”>INT 2F</A>)
30-31 CPM far jump vector for CPM (not an interrupt)
31 DPMI DOS Protected Mode Interface (for DOS extenders)
32 reserved
33 mouse support (see <A HREF=“int_33.html”>INT 33</A>)
34-3E Microsoft/Borland floating point emulation
3F overlay manager
40 BIOS hard disk
41 BIOS fixed disk 0 parameters pointer (see <A HREF=“int_13-9.html”>INT 13,9</A>)
42 BIOS relocated video handler (EGA/VGA/PS)
43 BIOS user font table (EGA/VGA/PS)
44 BIOS first 128 graphics characters (also Netware)
45 BIOS reserved for BIOS
46 BIOS fixed disk 1 parameters ptr (see <A HREF=“int_13-9.html”>INT 13,9</A>/INT 41)
47 BIOS reserved for BIOS
48 BIOS PCjr cordless keyboard translation
49 BIOS PCjr non-keyboard scancode translation table
4A BIOS user alarm (AT,CONV,PS/2) (see <A HREF=“int_4a.html”>INT 4A</A>)
4B-4F BIOS reserved
50 BIOS periodic alarm from timer (PS/2)
51-58 BIOS reserved
59 BIOS GSS Computer Graphics Interface
5A BIOS cluster adapter BIOS entry point
5B BIOS cluster adapter boot
5C NETBIOS NETBIOS interface, TOPS interface
5D-5F BIOS reserved for BIOS
60-67 reserved for user software interrupts
67 EMS LIM/EMS specification (see <A HREF=“int_67.html”>INT 67</A>)
69-6B reserved by IBM
6C DOS DOS 3.2 real time clock update
BIOS system resume vector
6D-6F reserved
70 IRQ8 real time clock (AT,XT286,PS50+, see <A HREF=“int_15.html”>INT 15</A>)
71 IRQ9 software redirected to IRQ2 (AT,XT286,PS50+)
72 IRQ10 reserved (AT,XT286,PS50+)
73 IRQ11 reserved (AT,XT286,PS50+)
74 IRQ12 mouse interrupt (PS50+)
75 IRQ13 numeric coprocessor NMI error (AT,XT286,PS50+)
76 IRQ14 fixed disk controller (AT,XT286,PS50+)
77 IRQ15 reserved (AT,XT286,PS50+)
78-79 unused
86-F0 DOS reserved for BASIC interpreter use
86 NETBIOS NETBIOS relocated INT 18
E0 CPM CP/M 86 function calls
F1-FF reserved by IBM
FE-FF may be destroyed by return from protected mode using VDISK on 286 machines (Apr 86, DDJ)
  • Intel defined 0 through 20h for use for internal CPU; IBM redefined interrupts 0 through 1Fh for its own use, hence the duplicate definitions in the tables
  • all interrupts except the internal CPU exceptions push the flags and the CS:IP of the next instruction onto the stack.
    CPU exception interrupts are similar but push the CS:IP of the causal instruction. 8086/88 divide exceptions are different, they return to the instruction following the division
  • interrupts are disabled upon entry into any interrupt routine and should be enabled by the user or by an IRET
  • in DOS 3.2+ hardware IRQ interrupts are re-vectored through DOS to provide standard stack frames
  • back2root/ibm-pc-ms-dos/hardware/irq.txt
  • Dernière modification : 2024/04/07 11:16
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