User`s guide

MAKEROM 11–3
ROM Header Information Fields
• Image Size
The image size is used by the SROM code to determine how much of the system
ROM should be loaded.
• Decompression Flag
The decompression flag tells the SROM code if the MAKEROM tool was used
to compress the ROM image with a “trivial repeating byte algorithm.” The
SROM code contains routines that perform this decompression algorithm. Other
compression/decompression schemes may be employed that work independently
from this one.
• Destination Address
This quadword contains the destination address for the image. The SROM code
will begin loading the image at this address and subsequently begin its
execution.
• Header Rev
The revision of the header specifications used in this header. This is necessary to
provide compatibility to future changes to this header specification. Version 0
headers are identified by the size of the header. See Header Size. For Version 1
or greater headers, this field must be set to a value of 1. The header revision for
Version 1 or greater headers is determined by the sum of this field and the
Header Rev Ext field. See Header Rev Ext.
• Firmware ID
The firmware ID is a byte that specifies the firmware type. This information
facilitates image boot options necessary to boot different operating systems.
Firmware ID
Firmware Type
(decimal) Description
DBM 0 Alpha Motherboards Debug Monitor firmware
WNT 1 Windows NT firmware
SRM 2 Alpha System Reference Manual Console
FSB 6 Alpha Motherboards Fail-Safe Booter
Milo 7 Linux Miniloader
VxWorks 8 VxWorks Real-Time Operating System
SROM 10 Serial ROM