[NUC] Error Codes During Boot for NUC

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[NUC] Error Codes During Boot for NUC

This document defines the error messages and POST codes that could be seen when starting an NUC.

In the tables below, POST codes and range values are in hexadecimal.

Error messages

Error Message	Explanation
CMOS Battery Low	The battery could be losing power. Replace the battery soon.
CMOS Checksum Error	The CMOS checksum is incorrect. CMOS memory can be corrupted. Try the following: Download and install the latest BIOS version for your NUC. Set the BIOS to factory defaults: Press F2 during boot to enter BIOS Setup. Press F9 to set factory defaults. Press F10 to save and exit BIOS.
Memory Size Decreased	Memory size has decreased since the last boot. If no memory was removed, the memory might be bad.
A Bootable Device has Not Been Detected	The NUC didn't find a bootable drive. This can happen if: The installed drive has failed.  Try the drive on another computer. Try a different known-good drive. The installed drive was moved from a different computer. You may need to perform a Windows Recovery or install a fresh copy of Windows. Be sure to first backup the data on the drive.

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.

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

Port 80h POST code ranges

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

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