Serious problems with OldWorld booting on a Mac 7300

[J. Blank]

..and also on a 7500!

I cannot get OldWorld boot to work AT ALL-- meaning that I ALSO cannot get
System 7.5.3 to boot (and I want to, for some silly reason-- humor me) on
my 7300 motherboard, or my 7500. Kernel version is 2.4.21-ben2, and I
cannot seem to get it to work:

* With a ROM I dumped from the 7500
* With a ROM I dumped from the 7300
* With a ROM from a 7200
* Reading the ROM from the machine itself
* Using a 7200 oftree
* Using an 8500 oftree

...and by the way, HOW DO YOU MAKE YOUR OWN OFTREES??!? I am AMAZED that
no one has ever provided documentation for that... or would a 7500 or 7300
oftree be identical to an 8500 or a 7200? (???)

Anyhow, the system boots up to the "Welcome to Macintosh" screen... and
goes no further. the CD keeps spinning. I have reproduced these symptoms
on System 7.5.3 and on OS 8...

The last I see is:

53c94 SCSI-driver installed (IRQs 12/0)
Could not register MESH SCSI unit. Need a second bus ??
Swim3 floppy driver installed
Hammerhead driver installed
4096K ROM mapped at 0x4fc00000 from 'rom/rom.7300'
Mapping GC at F3000000
dcbi treated as nop
dcbi treated as nop
[CLOCK_FIX_HACK]
Unmapping GC
Mapping GC at F3000000
+ Extending interrupt tree...
Routing mouse irq to 23
+ Mouse Driver v1.0
+ Extending interrupt tree...
Routing ablk irq to 25
+ Asynchronous Block Driver v1.4
+ DriveControlCmd IGNORED 48
+ Extending interrupt tree...
Routing video irq to 24
+ Video Driver v1.12


Please help.


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