Q: The Open Firmware version number displayed when I enter the user
interface seems to change with version numbers that do not increase with
time. Can you explain this fact?
A: Yes, I'm assuming the "version" to which you refer is from the Open
Firmware device tree/openprom node model property. Given that, the IEEE 1275 Section 3.5 "Standard System Nodes" defines this node as one having a
node property called "model." Annex A.2 "Specification" defines the model
property as one which is a "manufacturer-dependent" string. The string format
"is arbitrary." Therefore you may not assume a version number as one that
will increase as a function of time. The version number is meant to be used
by the Apple Open Firmware group. The numbers are unique and possess meaning
for their version control.
Here is a code example of a version number that is displayed when you enter the Open Firmware user interface, and that same version number (called a model property) in ther device tree. Note that your number most likely will be different.
Apple PowerMac1,1 1.1f4 BootROM built on 04/09/99 at 13:57:32
Copyright 1994-1999 Apple Computer, Inc.
All Rights Reserved.
OpenFirmware 3.1.1 <-----------here is the version number
To continue booting, type "mac-boot" and press return.
To shut down, type "shut-down" and press return.
ok
0 > dev /openprom ok <--------this is how to get to the openprom node
0 > .properties <--------------this is how to display the properties
name openprom
device_type BootROM
model OpenFirmware 3.1.1 <------and the version number
relative-addressing
supports-bootinfo
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In summary, the version number is a 1-to-1 transformation from the model property. It is unique. Therefore, version numbers are not a linear function of time in canonical form, y=mx+b. They are random, but unique.
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