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Port 80h POST Codes

This document defines the beep codes, error messages, and POST codes associated with BIOS versions based on Extensible Framework Interface (EFI).

Contents
BIOS error messages
Port 80h POST codes
POST code ranges
Typical POST sequence

BIOS error messages

Error Message Explanation
CMOS Battery Low The battery could be losing power. Replace the battery soon.
CMOS Checksum Bad The CMOS checksum is incorrect. CMOS memory can be corrupted. Run Setup to reset values.
Memory Size Decreased Memory size has decreased since the last boot. If no memory was removed, the memory might be bad.
No Boot Device Available System did not find a device to boot.

Port 80h POST codes
During the Power-On Self Test (POST), the BIOS sends progress codes (POST codes) to I/O port 80h. If the POST fails, the last POST code generated is left at port 80h. This code can be used to find out why the error occurred.

Port 80h POST code ranges
In the tables below, all POST codes and range values are listed in hexadecimal.

Range Category/Subsystem
00 – 0F Debug codes: Can be used by any PEIM/driver for debug
10 – 1F Host Processors
20 – 2F Memory/Chipset
30 – 3F Recovery
40 – 4F Reserved for future use
50 – 5F I/O Busses: PCI, USB, ISA, ATA, and so on.
60 – 6F Not currently used
70 – 7F Output Devices: All output consoles
80 – 8F Reserved for future use (new output console codes)
90 – 9F Input devices: Keyboard/Mouse
A0 – AF Reserved for future use (new input console codes)
B0 – BF Boot Devices: Includes fixed media and removable media.
C0 – CF Reserved for future use
D0 – DF Boot device selection
E0 – FF E0 - EE: Miscellaneous codes
F0 – FF: FF processor exception

Port 80h POST codes

POST Code Description of POST Operation
00 - 0F Debug Codes: can be used by any PEIM/driver for debug
10 - 1F Host Processor
10 Power-on initialization of the host processor (Boot Strap Processor)
11 Host processor Cache initialization (including APs)
12 Starting Application processor initialization
13 SMM initialization
14 LAN initialization
15 Exit early platform init driver
16 SMBUS driver initialization
17 Entry to SMBUS execute read/write
19 Entry to CK505 programming
1F Unrecoverable CPU error
20 - 2F Memory / Chipset
21 Initializing a chipset component
22 Reading SPD from memory DIMMs
23 Detecting presence of memory DIMMs
24 Programming timing parameters in the memory controller and the DIMMs
25 Configuring memory
26 Optimizing memory settings
27 Initializing memory, such as ECC init
28 Testing memory
2F No memory detected or no useful memory detected
30 - 3F Recovery
30 Crisis Recovery has initiated per User request
31 Crisis Recovery has initiated by software (corrupt flash)
34 Loading recovery capsule
35 Handing off control to the recovery capsule
3F Unable to recover
50 - 5F I/O Busses (PCI, USB, ISA, ATA, and so on.)
50 Enumerating PCI busses
51 Allocating resources to PCI bus
52 Hot Plug PCI controller initialization
53 – 57 Reserved for PCI Bus
58 Resetting USB bus
59 Reserved for USB
5A Resetting PATA/SATA bus and all devices
5B Reserved for ATA
5C Resetting SMBUS
5D Reserved for SMBUS
5F Unrecoverable I/O bus error
60 - 6F

There are currently no valid POST codes in the 60 - 6F range.

If you see a POST code in this range, it should be read as B0 - BF. (On a 7-segment LED display, the 'b' looks like a 6).

Example:

70 - 7F Output Devices
70 Resetting the VGA controller
71 Disabling the VGA controller
72 Enabling the VGA controller
78 Resetting the console controller
79 Disabling the console controller
7A Enabling the console controller
7F Unrecoverable output device error
90 - 9F Input Devices
90 Resetting keyboard
91 Disabling keyboard
92 Detecting presence of keyboard
93 Enabling the keyboard
94 Clearing keyboard input buffer
95 Instructing keyboard controller to run Self Test (PS2 only)
98 Resetting mouse
99 Disabling mouse
9A Detecting presence of mouse
9B Enabling mouse
9F Unrecoverable input device (keyboard or mouse) error
B0 - BF Boot Devices
B0 Resetting fixed media
B1 Disabling fixed media
B2 Detecting presence of a fixed media (IDE hard drive detection, and so on.)
B3 Enabling/configuring a fixed media
B8 Resetting removable media
B9 Disabling removable media
BA Detecting presence of a removable media (IDE, CD-ROM detection, and so on.)
BC Enabling/configuring a removable media
BF Unrecoverable boot device error
D0 - DF Boot Device Selection
Dy Trying boot selection y (y=0 to 15)
E0 - FF Miscellaneous Codes
E0 Started dispatching PEIMs (emitted on first report of EFI_SW_PC_INIT_BEGIN EFI_SW_PEI_PC_HANDOFF_TO_NEXT)
E2 Permanent memory found
E1, E3 Reserved for PEI/PEIMs
E4 Entered DXE phase
E5 Started dispatching drivers
E6 Started connecting drivers
E7 Waiting for user input
E8 Checking password
E9 Entering BIOS setup
EB Calling Legacy Option ROMs
EF Boot/S3 resume failure
F4 Entering Sleep state
F5 Exiting Sleep state
F8 EFI boot service ExitBootServices ( ) has been called
F9 EFI runtime service SetVirtualAddressMap ( ) has been called
FA EFI runtime service ResetSystem ( ) has been called
FF Processor exception

Typical Port 80h POST sequence
Port 80h code values typically increase during the boot process. The early codes are for subsystems closer to the processor and the later codes are for peripherals. Generally, the order of initialization is Processor -> Memory -> Busses -> Output/Input Devices -> Boot Devices. The sequence of POST is system-specific.

POST Code Description
21 Initializing a chipset component
22 Reading SPD from memory DIMMs
23 Detecting presence of memory DIMMs
25 Configuring memory
28 Testing memory
34 Loading recovery capsule
E4 Entered DXE phase
12 Starting Application processor initialization
13 SMM initialization
50 Enumerating PCI busses
51 Allocating resourced to PCI bus
92 Detecting the presence of the keyboard
90 Resetting keyboard
94 Clearing keyboard input buffer
95 Keyboard Self Test
EB Calling Video BIOS
58 Resetting USB bus
5A Resetting PATA/SATA bus and all devices
92 Detecting the presence of the keyboard
90 Resetting keyboard
94 Clearing keyboard input buffer
5A Resetting PATA/SATA bus and all devices
28 Testing memory
90 Resetting keyboard
94 Clearing keyboard input buffer
E7 Waiting for user input
01 INT 19
00 Ready to boot

This applies to:

Intel® NUC Board D33217CK
Intel® NUC Board D33217GKE
Intel® NUC Board D34010WYB
Intel® NUC Board D53427RKE
Intel® NUC Board D54250WYB
Intel® NUC Board DCP847SKE
Intel® NUC Board DE3815TYBE
Intel® NUC Kit D34010WYK
Intel® NUC Kit D54250WYK
Intel® NUC Kit DC3217BY
Intel® NUC Kit DC3217IYE
Intel® NUC Kit DC53427HYE
Intel® NUC Kit DCCP847DYE
Intel® NUC Kit DE3815TYKHE
Intel® NUC Kit DN2820FYKH

Solution ID: CS-034372
Last Modified: 05-Nov-2014
Date Created: 05-Jun-2013