Codici errore del BIOS
Alcune schede madri permettono l’individuazione degli errori hardware tramite un display a 2 caratteri, questi codici possono semplificare l’individuazione e la risoluzione dei problemi.
Tabella ACER
| 04 | CPU verification; POST start |
| 08 | Shutdown condition 0; Shutdown byte 0 |
| 0C | BIOS ROM checksum tested |
| 10 | CMOS ROM shutdown byte tested |
| 14 | DMA controller tested |
| 18 | System timer initialized |
| 1C | Memory refresh system tested |
| 1E | Memory type determined |
| 20 | Base 128K memory tested |
| 24 | 8042 keyboard controller tested |
| 28 | CPU descriptor instruction tested |
| 2C | 8259 PIT tested |
| 30 | Temporary Interrupts located and initialized |
| 34 | BIOS Interrupt vectors and routines configured |
| 38 | CMOS RAM tested |
| 3C | Memory size determined |
| 40 | Shutdown condition 1 |
| 44 | Video BIOS ROM initialized |
| 45 | RAM initialized and tested |
| 46 | Cache memory and controller initialized and tested |
| 48 | Memory tested |
| 4C | Shutdown condition 3 |
| 50 | Shutdown condition 2 |
| 54 | Shutdown condition 7 |
| 58 | Shutdown condition 6 |
| 5C | Keyboard and auxiliary I/O tested |
| 60 | BIOS Interrupt routines setup |
| 64 | RTC tested |
| 68 | Floppy drive and controller tested |
| 6C | Hard drive and controller tested |
| 70 | Parallel port tested |
| 74 | Serial port tested |
| 78 | Time of day setup |
| 7C | Optional ROM’s searched for and started |
| 80 | Math coprocessor tested |
| 84 | Keyboard tested |
| 88 | System initialized |
| 8C | System initialized |
| 90 | Operating system boot process started |
| 94 | Shutdown condition 5 |
| 98 | Shutdown condition A |
| 9C | Shutdown condition B |
Tabella ASUS
| POST code | What It Means |
|---|---|
| 8 | CPU not detected |
| 4B/FA | No DRAM detected/installed |
| F9/0D | DRAM training failed |
| 90/CF | DRAM recovery |
| 06 | DRAM unstable |
| A0-A2 | Boot up device unstable |
| B2 | External device unstable |
| D6 | Graphics card unstable |
| AA | Boot into the system |
Tabella Asrock
| POST Code | What It Means |
|---|---|
| FF, 00 – 19/D0-D3 | Reseat Memory and then clear CMOS |
| 31-3B/51-55 | Problem related to CPU and memory |
| D4-D5 | PCI resource allocation error |
| D6, 92-97 | Graphics card not recognized |
| D7 | Keyboard not recognized |
| 9A-9D | Problem related to USB devices |
| 03 | System entering sleep |
| AA | System is entering OS |
Tabella Compaq
| 00 | Initialize flags, MSW,IDTLIN |
| 01 | Read manufacturing jumper |
| 02 | 8042 received read command |
| 03 | No response from 8042 |
| 04 | Look for ROM at E000 |
| 05 | Look for ROM at C800 |
| 06 | Normal CMOS reset code |
| 08 | Initialize 8259,80287 |
| 09 | Reset code in CMOS byte |
| 0A | Vector vis 40:67 reset function |
| 0B | Vector vis 40:67 with E01 function |
| 0C | Boot reset function |
| 0D | Test #2 8254 PIT counter 0 |
| 0E | Test #2 8254 PIT counter 2 |
| 0F | Warm boot |
| 10 | PPI disabled, test 8254 PIT’s 0 and 1 |
| 11 | Initialize (blast) VDU controller |
| 12 | Clear screen; turn ON video |
| 13 | Test time 0 |
| 14 | Disable RTC interrupts |
| 15 | Check battery power |
| 16 | Battery has lost power |
| 17 | Clear CMOS Diags. |
| 18 | Test base memory (First 128K) |
| 19 | Initialize base memory |
| 1A | Initialize VDU adapters |
| 1B | The system ROM |
| 1C | CMOS checksum |
| 1D | DMA controller/page registers |
| 1E | Test keyboard controller |
| 1F | Test 286 protected mode |
| 20 | Test real and extended memory |
| 21 | Initialize time-of-day |
| 22 | Initialize 287 coprocessor |
| 23 | Test the keyboard and 8042 |
| 24 | Reset A20, set default CPU speed |
| 25 | Test diskette subsystem |
| 26 | Test fixed disk subsystem |
| 27 | Initialize parallel printer |
| 28 | Perform search for optional ROM’s |
| 29 | Test valid system configuration |
| 2A | Clear screen |
| 2B | Check for invalid time and date |
| 2C | Optional ROM search |
| 2D | Test timer 2 |
| 2F | Write to diagnostic byte |
| 30 | Clear first 128K bytes of RAM |
| 31 | Load interrupt vectors 70-77 |
| 32 | Load interrupt vectors 00-1F |
| 33 | Initialize MEMSIZE and RESETWD |
| 34 | Verify CMOS checksum |
| 35 | CMOS checksum is not valid |
| 36 | Check battery power |
| 37 | Check for game adapters |
| 38 | Check for Serial ports |
| 39 | Check for parallel printer ports |
| 3A | Initialize port and comm time-outs |
| 3B | Flush keyboard buffer |
| 40 | Save RESETWD value |
| 41 | Check RAM refresh |
| 42 | Start write of 128K RAM test |
| 43 | Reset parity checks |
| 44 | Start verify of 128K RAM test |
| 45 | Check for parity errors |
| 46 | NO RAM errors |
| 47 | RAM error detected |
| 50 | Check for dual frequency in CMOS |
| 51 | Check CMOS VDU configuration |
| 52 | Start VDU ROM search |
| 53 | Vector to VDU option ROM’s |
| 54 | Initialize first display adapter |
| 55 | Initialize second display adapter |
| 56 | No display adapters installed |
| 57 | Initialize primary VDU mode |
| 58 | Start of VDU test (each adapter) |
| 59 | Check existence of adapter |
| 5A | Check VDU registers |
| 5B | Start screen memory test |
| 5C | End test of adapter, clear memory |
| 5D | Error detected on an adapter |
| 5E | Test the next adapter |
| 5F | All adapters successfully tested |
| 60 | Start of memory tests |
| 61 | Enter protected mode |
| 62 | Start memory sizing |
| 63 | Get CMOS size |
| 64 | Start test of real memory |
| 65 | Start test of extended memory |
| 66 | Save size memory (base, ext) |
| 67 | 128K-option installed CMOS bit |
| 68 | Prepare to return to real mode |
| 69 | Back in real mode-successful |
| 6A | Protected mode error during test |
| 6B | Display error message |
| 6C | End of memory test |
| 6D | Initialize KB OK string |
| 6E | Determine size to test |
| 6F | Start MEMTEST |
| 70 | Display XXXXXKB OK |
| 71 | Test each RAM segment |
| 72 | High order address test |
| 73 | Exit MEMTEST |
| 74 | Parity error on bus |
| 75 | Start protected mode test |
| 76 | Prepare to enter protected mode |
| 77 | Test software exceptions |
| 78 | Prepare to return to real mode |
| 79 | Back in real mode-successful |
| 7A | Back in real mode-error occurred |
| 7B | Exit protected mode |
| 7C | High order address test failure |
| 7D | Entered cache controller test |
| 7E | Programming memory cache |
| 7F | Copy system ROM to high RAM |
| 80 | Start of 8042 test |
| 81 | Do 8042 self test |
| 82 | Check result received |
| 83 | Error result |
| 84 | OK 8042, Init mode=5D |
| 86 | Start test, reset keyboard |
| 87 | Got acknowledge, read result |
| 88 | Got result, check it |
| 89 | Test for stuck keys |
| 8B | Test keyboard interface |
| 8A | Key seems to be stuck |
| 8C | Got result, check it |
| 8D | End of test, no errors |
| 90 | Start of CMOS test |
| 91 | CMOS seems to be OK |
| 92 | Error on CMOS read,write test |
| 93 | Start of DMA controller test |
| 94 | Page registers seem to be OK |
| 95 | DMA controller is OK |
| 96 | 8237 initialization is complete |
| 97 | Start of NCA RAM test |
| A0 | Start of diskette tests |
| A1 | FDC reset active (3F2h Bit 2) |
| A2 | FDC reset inactive (3F2h Bit 2) |
| A3 | FDC motor on |
| A4 | FDC time-out error |
| A5 | FDC failed reset |
| A6 | FDC passed reset |
| A8 | Start to determine drive type |
| A9 | Seek operation initialized |
| AA | Waiting for FDC seek status |
| AF | Diskette tests complete |
| B0 | Start of fixed drive tests |
| B1 | Combo board not found-exit |
| B2 | Combo controller failed-exit |
| B3 | Testing drive 1 |
| B4 | Testing drive 2 |
| B5 | Drive error (error condition) |
| B6 | Drive failed (failed to respond) |
| B7 | No fixed drives-exit |
| B8 | Fixed drive tests complete |
| B9 | Attempt to boot diskette |
| BA | Attempt to boot fixed drive |
| BB | Boot attempt failed FD/HD |
| BC | Jump to boot record |
| BD | Drive error, retry booting |
| BE | Weitek coprocessor test |
| D0 | Entry to clear memory routine |
| D1 | Ready to go to protected mode |
| D2 | Ready to clear extended memory |
| D3 | Ready to reset back to real mode |
| D4 | Back in real mode |
| D5 | Clear base memory |
| DD | Built-in self-test failed |
| E0 | Ready to replace E000 ROM |
| E1 | Completed E000 ROM replacement |
| E2 | Ready to replace EGA ROM |
| E3 | Completes EGA ROM replacement |
Tabella Dell
| 01 | CPU register test in progress |
| 02 | CMOS read/write test failed |
| 03 | BIOS ROM checksum bad |
| 04 | 8254 programmable interrupt controller failed |
| 05 | DMA controller initialization failed |
| 06 | DMA page-register test failed |
| 08 | RAM refresh verification failed |
| 09 | Starting first-64K RAM test |
| 0A | First-64KB RAM IC or data line bad |
| 0B | First-64KB RAM odd/even logic bad |
| 0C | First-64KB address line bad |
| 0D | First-64KB parity error |
| 10 | Bit 0 bad in first 64KB |
| 11 | Bit 1 bad in first 64KB |
| 12 | Bit 2 bad in first 64KB |
| 13 | Bit 3 bad in first 64KB |
| 14 | Bit 4 bad in first 64KB |
| 15 | Bit 5 bad in first 64KB |
| 16 | Bit 6 bad in first 64KB |
| 17 | Bit 7 bad in first 64KB |
| 18 | Bit 8 bad in first 64KB |
| 19 | Bit 9 bad in first 64KB |
| 1A | Bit 10 bad in first 64KB |
| 1B | Bit 11 bad in first 64KB |
| 1C | Bit 12 bad in first 64KB |
| 1D | Bit 13 bad in first 64KB |
| 1E | Bit 14 bad in first 64KB |
| 1F | Bit 15 bad in first 64KB |
| 20 | Slave DMA register bad |
| 21 | Master DMA register bad |
| 22 | Master interrupt-mask register bad |
| 23 | Slave interrupt-mask register bad |
| 25 | Loading interrupt vectors |
| 27 | Keyboard-controller test failed |
| 28 | CMOS RAM battery bad |
| 29 | CMOS configuration validation in progress |
| 2B | Video-memory test failed |
| 2C | Video initialization failure |
| 2D | Video-retrace failure |
| 2E | Searching for a video ROM |
| 30 | Switching to video ROM |
| 31 | Monochrome operation OK |
| 32 | Color (CGA) operation OK |
| 33 | Color operation OK |
| 34 | Timer-tick interrupt in progress (or bad) |
| 35 | CMOS shutdown test in progress (or bad) |
| 36 | Gate A20 bad |
| 37 | Unexpected interrupt in protected mode |
| 38 | RAM test in progress or high address line is bad |
| 3A | Interval timer channel 2 bad |
| 3B | Time-of-day test bad |
| 3C | Serial-port test bad |
| 3D | Parallel -port test bad |
| 3E | Math co-processor test bad |
| 3F | Cache-memory test bad |
Tabella HP Pavillion
| 02 | Verify real mode |
| 03 | Disable NMI |
| 04 | Get processor type |
| 06 | Initialize system hardware |
| 08 | Initialize chipset with POST values |
| 09 | Set IN-POST flags |
| 0A | Initialize CPU registers |
| 0B | Enable CPU registers |
| 0C | Initialize cache to POST values |
| 0E | Initialize I/O component |
| 0F | Initialize local IDE bus |
| 10 | Initialize power management |
| 11 | Load alternate registers |
| 12 | Restore CPU control word during warm boot |
| 13 | Initialize PCI bus mastering devices |
| 14 | Initialize keyboard controller |
| 16 | BIOS ROM checksum |
| 17 | Initialize cache before memory size |
| 18 | Initialize 8254 timer |
| 1A | Initialize DMA controller |
| 1C | Reset PIC |
| 20 | Test DRAM refresh |
| 22 | Test 8742 keyboard controller |
| 24 | Set ES segment register to 4GB |
| 26 | Enable A-20 line |
| 28 | Autosize DRAM |
| 29 | Initialize POST memory manager |
| 2A | Clear 512K base RAM |
| 2C | RAM address line failure |
| 2E | RAM data failure, low byte |
| 2F | Enable cache before BIOS shadow |
| 30 | RAM data failure, high byte |
| 32 | Test CPU, BUS clock frequency |
| 33 | Initialize POST dispatch manager |
| 34 | Test CMOS RAM |
| 35 | Initialize alternate chipset registers |
| 36 | Warm start shut-down |
| 37 | Reinitialize chipset (MB only) |
| 38 | Shadow system BIOS ROM |
| 39 | Reinitialize cache (MB only) |
| 3A | Autosize cache |
| 3C | Configure advanced chipset registers |
| 3D | Load alternate registers new CMOS values |
| 40 | Set initial CPU speed |
| 42 | Initialize interrupts |
| 44 | Initialize BIOS interrupts |
| 45 | POST device initialization |
| 46 | Check ROM copyright notice |
| 47 | Initialize manager for PCI option ROM’s |
| 48 | Check video config against CMOS |
| 49 | Initialize manager for PCI option ROM’s |
| 4A | Initialize all video adapters |
| 4B | Display quiet boot screen |
| 4C | Shadow video BIOS |
| 4E | Display BIOS copyright notice |
| 50 | Display CPU type & speed |
| 51 | Initialize |
| 52 | Test keyboard |
| 54 | Set key click if enabled |
| 56 | Enable keyboard |
| 58 | Test for unexpected interrupts |
| 59 | Initialize POST display service |
| 5A | Display “Press F2 to Enter Setup” |
| 5B | Disable CPU cache |
| 5C | Test RAM, 512-640K |
| 60 | Test extended memory |
| 62 | Test extended memory address lines |
| 64 | Jump to user patch 1 |
| 66 | Configure advanced cache registers |
| 67 | Initialize multi-processor APIC |
| 68 | Enable external & processor caches |
| 69 | Set up SMM area |
| 6A | Display external L2 cache size |
| 6C | Display shadow area message |
| 6E | Display high address for UMB recovery |
| 70 | Display error message |
| 72 | Check for configuration errors |
| 74 | Test real time clock |
| 76 | Check for keyboard errors |
| 7A | Test for key lock on |
| 7C | Set up hardware interrupt vectors |
| 7E | Initialize coprocessor, if present |
| 80 | Disable onboard super I/O ports |
| 81 | Late POST device initialization |
| 82 | Detect & install external RS-232 ports |
| 83 | Configure non-MDC IDE controllers |
| 84 | Detect & install external parallel ports |
| 85 | Initialize PnP ISA devices |
| 86 | Reinitialize onboard I/O ports |
| 87 | Configure motherboard configurable devices |
| 88 | Initialize BIOS data area |
| 89 | Enable NMI’s |
| 8A | Initialize extended BIOS data area |
| 8B | Test & initialize PS/2 mouse |
| 8C | Initialize floppy controller |
| 8F | Determine number of ATA drives |
| 90 | Initialize hard disk controllers |
| 91 | Initialize local BUS HD controllers |
| 92 | Jump to user patch 2 |
| 93 | Build MPTABLE for multiprocessor boards |
| 94 | Disable A-20 line |
| 95 | Install CD-ROM for boot |
| 96 | Clear huge ES segment register |
| 97 | Fix up multiprocessor table |
| 98 | Search for options ROM’s |
| 99 | Check for smart drive |
| 9A | Shadow ROM option |
| 9C | Set up power management |
| 9E | Enable hardware interrupts |
| 9F | Determine number of ATA & SCSI drives |
| A0 | Set time of day |
| A2 | Check key lock |
| A4 | Initialize typematic rate |
| A8 | Erase F2 prompt |
| AA | Scan for F2 keystroke |
| AC | Enter SETUP |
| AE | Clear IN-POST flag |
| B0 | Check for errors |
| B2 | POST done, prepare for boot |
| B4 | One short beep before boot |
| B5 | Terminate quiet boot |
| B6 | Check password (optional) |
| B8 | Clear global descriptor table |
| B9 | Clean up all graphics |
| BA | Initialize DMI parameters |
| BB | Initialize PnP option ROM’s |
| BC | Clear parity checkers |
| BD | Display multi boot menu |
| BE | Clear screen optional |
| BF | Check virus and backup reminders |
| C0 | Try to boot with Int 19 |
| C1 | Initialize POST error manager |
| C2 | Initialize error logging |
| C3 | Initialize error display function |
| C4 | Initialize system error handler |
| E0 | Initialize the chipset |
| E1 | Initialize the bridge |
| E2 | Initialize the processor |
| E3 | Initialize system timer |
| E4 | Initialize system I/O |
| E5 | Check force recovery boot |
| E6 | Checksum BIOS ROM |
| E7 | Got to BIOS |
| E8 | Set huge segment |
| E9 | Initialize multiprocessor |
| EA | Initialize OEM special code |
| EB | Initialize PIC & DMA |
| EC | Initialize memory type |
| ED | Initialize memory type |
| EE | Shadow boot block |
| EF | System memory test |
| F0 | Initialize interrupt vectors |
| F1 | Initialize runtime clock |
| F2 | Initialize video |
| F3 | Initialize beeper |
| F4 | Initialize BOOT |
| F5 | Clear huge segment |
| F6 | Boot to mini-DOS |
| F7 | Boot to full DOS |
Tabella Phoenix BIOS
| 02 | Verify real mode |
| 03 | Disable non-maskable interrupt (NMI) |
| 04 | Get CPU type |
| 06 | Initialize system hardware |
| 07 | Disable shadow and execute code from the ROM |
| 08 | Initialize chipset with initial POST values |
| 09 | Set IN POST flag |
| 0A | Initialize CPU registers |
| 0B | Enable CPU cache |
| 0C | Initialize caches to initial POST values |
| 0E | Initialize I/O component |
| 0F | Initialize the local bus IDE |
| 10 | initialize power management |
| 11 | Load alternate registers with initial POST values |
| 12 | Restore CPU control word during warm boot |
| 13 | Initialize PCI bus mastering devices |
| 14 | Initialize keyboard controller |
| 16 | BIOS ROM checksum |
| 17 | Initialize cache before memory autosize |
| 18 | 8254 programmable interrupt timer initialization |
| 1A | 8237 DMA controller initialization |
| 1C | Reset programmable interrupt controller |
| 20 | Test DRAM refresh |
| 22 | Test 8742 keyboard controller |
| 24 | Set ES segment register to 4GB |
| 26 | Enable gate A20 line |
| 28 | Autosize DRAM |
| 29 | Initialize POST memory manager |
| 2A | Clear 512KB base RAM |
| 2C | RAM failure on address line xxxx |
| 2E | RAM failure on data bits xxxx of low byte of memory bus |
| 2F | Enable cache before system BIOS shadow |
| 30 | RAM failure on data bits xxxx of high byte of memory bus |
| 32 | Test CPU bus clock frequency |
| 33 | Initialize Phoenix Dispatch Manager |
| 36 | Warm start shut down |
| 38 | Shadow system BIOS ROM |
| 3A | Autosize cache |
| 3C | Advanced configuration of chipset registers |
| 3D | Load alternate registers with CMOS values |
| 41 | Initialize extended memory for RomPilot |
| 42 | Initialize interrupt vectors |
| 45 | POST device initialization |
| 46 | Check ROM copyright notice |
| 47 | Initialize I20 support |
| 48 | Check video configuration against CMOS |
| 49 | Initialize PCI bus and devices |
| 4A | Initialize all video adapters in system |
| 4B | QuietBoot start (optional) |
| 4C | Shadow video BIOS ROM |
| 4E | Display BIOS copyright notice |
| 4F | Initialize MultiBoot |
| 50 | Display CPU type and speed |
| 51 | Initialize EISA board |
| 52 | Test keyboard |
| 54 | Set key click if enabled |
| 55 | Enable USB devices |
| 58 | Test for unexpected interrupts |
| 59 | Initialize POST display service |
| 5A | Display prompt “Press F2 to enter SETUP” |
| 5B | Disable CPU cache |
| 5C | Test RAM between 512KB and 640KB |
| 60 | Test extended memory |
| 62 | Test extended memory address lines |
| 64 | Jump to UserPatch1 |
| 66 | Configure advanced cache registers |
| 67 | Initialize Multi Processor APIC |
| 68 | Enable external and CPU caches |
| 69 | Setup system management mode (SMM) area |
| 6A | Display external L2 cache size |
| 6B | Load custom defaults (optional) |
| 6C | Display shadow area message |
| 6E | Display possible high address for UMB recovery |
| 70 | Display error messages |
| 72 | Check for configuration errors |
| 76 | Check for keyboard errors |
| 7C | Set up hardware interrupt vectors |
| 7D | Initialize Intelligent System Monitoring |
| 7E | Initialize coprocessor if present |
| 80 | Disable onboard super I/O ports and IRQ’s |
| 81 | Late POST device initialization |
| 82 | Detect and install external RS232 ports |
| 83 | Configure non-MCD IDE controllers |
| 84 | Detect and install external parallel ports |
| 85 | Initialize PC compatible PnP ISA devices |
| 86 | Reinitialize onboard I/O ports |
| 87 | Configure motherboard configurable devices (optional) |
| 88 | Initialize BIOS data area |
| 89 | Enable non-maskable interrupts (NMI’s) |
| 8A | Initialize extended BIOS data area |
| 8B | Test and initialize PS/2 mouse |
| 8C | Initialize floppy controller |
| 8F | Determine number of ATA drives (optional) |
| 90 | Initialize hard disk controllers |
| 91 | Initialize local bus hard disk controllers |
| 92 | Jump to UserPatch2 |
| 93 | Build MPTABLE for multi processor boards |
| 95 | Install CD ROM for boot |
| 96 | Clear huge ES segment register |
| 97 | Fixup multi processor table |
| 98 | Search for option ROM’s |
| 99 | Check for SMART drive (optional) |
| 9A | Shadow option ROM’s |
| 9C | Set up power management |
| 9D | Initialize security engine (optional) |
| 9E | Enable hardware interrupts |
| 9F | Determine number of ATA and SCSI drives |
| A0 | Set time of day |
| A2 | Check key lock |
| A4 | Initialize typematic rate |
| A8 | Erase F2 prompt |
| AA | Scan for F2 key stroke |
| AC | Enter setup |
| AE | Clear boot flag |
| B0 | Check for errors |
| B1 | Inform RomPilot about the end of POST |
| B2 | POST done – prepare to boot operating system |
| B4 | One short beep |
| B5 | Terminate QuietBoot (optional) |
| B6 | Check password |
| B7 | Initialize ACPI BIOS |
| B9 | Prepare boot |
| BA | Initialize DMI parameters |
| BB | Initialize PnP option ROM’s |
| BC | Clear parity checkers |
| BD | Display multiboot menu |
| BE | Clear screen |
| BF | Check virus and backup reminders |
| C0 | Try to boot with interrupt 19 |
| C1 | Initialize POST Error Manager (PEM) |
| C2 | Initialize error logging |
| C3 | Initialize error display function |
| C4 | Initialize system error handler |
| C5 | PnP dual CMOS (optional) |
| C6 | Initialize notebook docking (optional) |
| C7 | Initialize notebook docking late |
| C8 | Force check (optional) |
| C9 | Extended checksum (optional) |
| CA | Redirect Int 15h to enable remote keyboard |
| CB | Redirect Int 13 to Memory Technologies Devices such as ROM, RAM, PCMCIA, and serial disk |
| CC | Redirect Int 10h to enable remote serial video |
| CD | Re-map I/O and memory for PCMCIA |
| CE | Initialize digitizer and dispaly message |
| D2 | Unknown interrupt |
| The following are for boot block in Flash ROM | |
| E0 | Initialize the chipset |
| E1 | Initialize the bridge |
| E2 | Initialize the CPU |
| E3 | Initialize the system timer |
| E4 | Initialize system I/O |
| E5 | Check force recovery boot |
| E6 | Checksum BIOS ROM |
| E7 | Go to BIOS |
| E8 | Set Huge Segment |
| E9 | Initialize Multi Processor |
| EA | Initialize OEM special code |
| EB | initialize PIC and DMA |
| EC | Initialize Memory type |
| ED | Initialize Memory size |
| EE | Shadow Boot Block |
| EF | System memory test |
| F0 | Initialize interrupt vectors |
| F1 | Initialize Run Time Clock |
| F2 | Initialize video |
| F3 | Initialize System Management Menager |
| F4 | Output one beep |
| F5 | Clear Huge Segement |
| F6 | Boot to mini DOS |
| F7 | Boot to Full DOS |