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Microid Research "Mr. Bios" BIOS Post Codes

  • 00 - Cold-Boot Commences (Not Seen with Warm-Boot)
  • 01 - HOOK 00 OEM Specific, Typically Restores Chipset to Default
  • 02 - Disable Critical I/O: 6845s, 8237s, 765, and Parity Latches
  • 03 - ROM BIOS Checksum Test
  • 04 - Page Register Test (Ports 81-8F)
  • 05 - 8042 (Keyboard Controller) Selftest
  • 06 - 8237-slave/master, 8254-ch2/1, RTC-REG-F/A, 8259-master/slave
  • 07 - Memory Refresh Circuit test
  • 08 - Master (16 bit) DMA Controller Failure
  • 08 - Slave (8 bit) DMA Controller Failure
  • 09 - HOOK 01 OEM Specific, Typically Disables Cache, Shadow
  • 0A - Base 64K Memory Test - Beep Code Describes Failure
  • 0B - Master 8259 (Port 21) or Slave 8259 (Port A1) Failure
  • 0C - 8259/IRQ tests - Beep Code Describes Failure
  • 0D - 8254 Channel-0 Test and Initialization
  • 0E - 8254 Channel-2 (Speaker) Failure
  • 0F - CMOS RAM Read/Write Test Failure or RTC Periodic Interrupt / IRQ8 Failure, refer to beep code
  • 10 - Video Initialization and (Cold-Boot) Signon Message
  • 11 - CMOS Checksum Test
  • 12 - Keyboard Controller Failure
  • 13 - HOOK 02 OEM Specific
  • 14 - Size/Test Base Memory (Low 64K Already Done)
  • 15 - Perform 2nd Try KB Init, if Necessary
  • 16 - HOOK 03 Size/Test Cache, Other OEM Unique Code
  • 17 - A20 Test Failure Due to 8042 Timeout
  • 18 - Size/Test Extended Memory
  • 19 - Memory Parity Error or IUO Channel Error, refer to beep code
  • 1A - Real Time Clock (RTC) Settings are invalid or is not updating
  • 1B - Serial Port Determination Off-board/On-board
  • 1C - Parallel Port Determination, Off-board/On-board
  • 1D - Coprocessor Determination/Initialization
  • 1E - Floppy Controller Test/Determination, CMOS Validation
  • 1F - Fixed Disk Controller Test/Determination, CMOS Validation
  • 20 - Rigorous CMOS Parameter Validation
  • 21 - Front-Panel Lock Check, Wait for User to Acknowledge Errors
  • 22 - Set NumLock, Password-Security Trap, Dispatch to Setup-Utility
  • 23 - HOOK 05 OEM Specific
  • 24 - Set Typematic Rate
  • 25 - Floppy Subsystem Initialization
  • 26 - Fixed Subsystem Initialization
  • 27 - ACK Errors, Set Primary Adaptor Video Mode
  • 28 - HOOK 06 OEM Specific, Typically Enables Shadow, Cache, Speed
  • 29 - Adaptor ROM Installation
  • 2A - ACK Errors, set Video Mode, Set DOS Time Variables From RTC
  • 2B - Enable Parity Checking and NMI
  • 2C - Set Low Stack, Install E000 ROM
  • 2D - ACK Errors, Set Primary Video Mode
  • 2E - HOOK 07 OEM Specific
  • 2F - Pass Control to INT19 (Boot Disk)
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