Browse Prior Art Database

Algorithm to Allow a Computer System's BootROM in Compressed Form

IP.com Disclosure Number: IPCOM000112295D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Dawkins, GJ: AUTHOR [+3]

Abstract

Disclosed is an algorithm by which the BootROM of a computer system can be compressed in order to increase the effective size of the BootROM and thus avoid the cost of having to use a larger ROM device for the storage of increasingly expaning bootROM code to support any new bootable devices or adapters.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Algorithm to Allow a Computer System's BootROM in Compressed Form

      Disclosed is an algorithm by which the BootROM of a computer
system can be compressed in order to increase the effective size of
the BootROM and thus avoid the cost of having to use a larger ROM
device for the storage of increasingly expaning bootROM code to
support any new bootable devices or adapters.

      Theoretically, any compression method shall allow a large
quantity of information be stored with significantly less storage
space.  From the practical storage device point of view, the
effective size of the storage device is increased by the use of a
lossless compression technique.  Being a storage device, a computer
system's BootROM is compressible.

      Like any compressed storage device, a mechanism must also exist
to decompress the information before it can be used.  Normally, this
is the task of a device driver when an application requests a piece
of data from the storage device.  Interestingly, the consumer of the
system BootROM is the system processor.

      When a computer system is powered on, its processor begins to
fetch, decode, and execute the stream of instructions coming from its
BootROM.  Since the processor will not understand any invalid
instruction, BootROM code can't be fully 100% in compressed form.
BootROM must have a function to handle its decompression before the
processor attempts to use any code from the compressed area of the
BootROM.

      In order to apply code compression to the BootROM, The
following procedure must be followed.

1.  Partition the entire BootROM code into thr...