American Megatrends Apollo IV User Manual page 72

Bootblock Code Checkpoint Codes
Code
E0h Verify the bootblock BIOS checksum. Disable the internal cache, DMA, and
interrupt controllers. Initialize the system timer. Start memory refresh.
E1h Initialize the chipset registers. Set the BIOS size to 128K. Make the 512 KB
base memory available.
E2h Test the base 64 KB of system memory. Send the BAT command to the
keyboard controller. Make sure that <Ctrl> <Home> was pressed. Verify the
main system BIOS checksum.
E3h The main system BIOS is good. Transfer control to the main system BIOS.
E4h Start the memory test.
E5h The memory test is over. Initialize the interrupt vector table.
E6h Initialize the DMA and interrupt controllers.
E7h Determine the CPU internal clock frequency.
E8h Initialize the I/O chipset, if any.
E9h Program the CPU clock-dependent chip set parameters.
EAh Enable the timer and the floppy diskette interrupt. Enable the internal cache.
Copy the bootblock BIOS and pass control to the bootblock BIOS in the 0000h
segment.
EDh Initialize the floppy drive.
EEh Look for a diskette in drive A:. Read the first sector of the diskette.
EFh Floppy read error.
F0h Search for AMIBOOT.ROM in the root directory of the floppy diskette in drive
A:.
F1h The AMIBOOT.ROM file is not in the root directory.
F2h Read the FAT. Analyze the FAT to find the clusters occupied by the
AMIBOOT.ROM.
F3h Start reading the AMIBOOT.ROM file, cluster by cluster.
F4h The AMIBOOT.ROM file is not the correct size.
F5h Disable the internal cache. Raise the Vpp. Enable Flash write and reset the
Flash ROM.
FBh Detect the flash type.
FCh Start erasing flash blocks.
FDh Program the Flash ROM in the E0000-EFFFFh region.
FEh Start programming Flash at F0000-FFFFF region.
FFh Flash programming is successful. The computer reboots.
68 Apollo IV PCI Pentium ISA Motherboard User's Guide
Description