Acer Veriton Z291G Service Guide - Page 57

Checkpoint D4 D5 D6 D7 D8 D9 DA Description Test base 512 KB memory. Adjust policies and cache first 8 MB. Set stack. Bootblock code is copied from ROM to lower system memory and control is given to it. BIOS now executes out of RAM. Both key sequence and OEM specific method is checked to determine if BIOS recovery is forced. Main BIOS checksum is tested. If BIOS recovery is necessary, control flows to checkpoint E0. See the "Boot Block Recovery Code Checkpoints" section for more information. Restore CPUID value back into register. The Bootblock Runtime interface module is moved to system memory and control is given to it. Determine whether to execute serial flash. The Runtime module is uncompressed into memory. CPUID information is stored in memory. Store the Uncompressed pointer for future use in PMM. Copying Main BIOS into memory. Leaves all RAM below 1 MB Read-Write including E000 and F000 shadow areas but closing SMRAM. Restore CPUID value back into register. Give control to BIOS POST (ExecutePOSTKernel). See the "POST Code Checkpoints" section for more information. Boot Block Recovery Code Checkpoints The boot block recovery code gets control when the BIOS determines that a BIOS recovery is required because the user has forced the update or the BIOS checksum is corrupt. Refer to "BIOS Recovery" section on page 61 for more information. The following table describes the type of checkpoints that may occur during the boot block recovery portion of the BIOS. Checkpoint E0 E9 EA EB EF E9 or EA F0 F1 F2 F3 F5 FA FB F4 FC FD FF Description Initialize the floppy controller in the super I/O. Some interrupt vectors are initialized. DMA controller is initialized. 8259 interrupt controller is initialized. L1 cache is enabled. Set up floppy controller and data. Attempt to read from floppy. Enable ATAPI hardware. Attempt to read from ARMD and ATAPI CDROM. Disable ATAPI hardware. Jump back to checkpoint E9. Read error occurred on media. Jump back to checkpoint EB. Determine information about root directory of recovery media. Search for pre-defined recovery file name in root directory. Recovery file not found. Start reading FAT table and analyze FAT to find the clusters occupied by the recovery file. Start reading the recovery file cluster by cluster. Disable L1 cache. Check the validity of the recovery file configuration to the current configuration of the flash part. Make flash write enabled through chipset and OEM specific method. Detect proper flash part. Verify that the found flash part size equals the recovery file size. The recovery file size does not equal the found flash part size. Erase the flash part. Program the flash part. The flash has been updated successfully. Make flash write disabled. Disable ATAPI hardware. Restore CPUID value back into register. Give control to F000 ROM at F000:FFF0h. Veriton Z290G AIO Computer Service Guide 49