Robert Gray <[EMAIL PROTECTED]> wrote:
>Subject: Re: Clearing up an old argument....finally spelled right
>
>> ...my external CD-ROM's software operates as an extension...how
>> on earth could I use it to install software? Would not the OS
>> CD-ROM have to be used as the startup disc?
>
> So, hold down the c key and use the OS CD as the startup disk.
This is one of those persistant misunderstandings relating to Apple's
closed CD driver. Whether Apple's CD driver may or may not work with your
third party CD drive is almost entirely irrelevant when booting from a
bootable CD.
Definitions:
CD - the shiny disk itself, including commercial 'stamped' CDs,
and CD-R and RWs
CD reader or drive - the box plugged somehow into your Mac
that spins and reads the CD
CD driver - the software the Mac uses to access the CD reader
hardware
and the information on the CD itself
A CD is not bootable unless it has a disk driver written to its
bootblocks, an area of the CD which nearly all CD drives can read before
any driver has loaded. The driver in the CD's bootblocks is not visible
on the CD itself but _is_ there (else the CD wouldn't be bootable.) This
driver is almost totally make-model-ROM agnostic. It doesn't care if the
CD drive is an Apple mechanism or not, but will load and boot from most
any CD reader. The few times I've been unable to boot from a CD mechanism
have all been caused by problems other than the CD drive's
make-model-"ROM"s, including defective drives, bad cabling, scsi ID and
term problems, incompatible CD-R media etc.
The CD's driver is not the driver inside a bootable CDs System Folder,
it's located in the CD's bootblocks and doesn't care a whit if Apple's
"ROM"s are present in the reader's hardware or not.
If one is unable to boot from a known-good bootable CD, the chances are
extremely good the problem is _not_ the make, model or "ROM"s of the CD
drive. To boot from a _known_good_bootable_ CD (some already mentioned by
others):
* hold down the "C" key immediately after startup chimes. Implimented in
most
models from the LC III onward, the Mac tries to boot from the
default CD device
address. In Macs which shipped with scsi CD drives the default
address is
scsi bus 0: ID 3, Macs with atapi CD drives boot from ATA bus 1:
master (IIRC).
As noted, atypically for Macs of its era, the PB1400 cannot be
booted from
its internal CD drive using the "C" key, why this is so I'd like to
know. I wonder
if it will boot from an external scsi CD at ID3? I'll have to test
this sometime . . .
* hold down cmd-option-shift-delete, which forces the Mac to
disregard the previously chosen boot _device_ (NOT volume) and
search for other
bootable devices. However if bootable disks or devices other than
the CD drive are
present the Mac may boot from one of those before it finds the CD.
* Physically disconnect any other devices, bootable and otherwise,
usually not easy on a PB, but as
with all troubleshooting, the simpler the configuration the easier
the TSing.
* Ensure the CD reader is actually functional, including the cabling,
jumper settings (ID or master/slave), and termination (if scsi).
It's surprisingly easy to overlook this basic troubleshooting step.
* Some CD readers have trouble reading some CD-R or (RW) media
brands and/or types, so knowing a CD-R will boot one Mac
does not ensure it will boot in any Mac's CD reader. Generally
however
if the CD-R _media_ is readable in the suspect configuration, it
will be
bootable as well (assuming it's been correctly made.)
Any questions?
Dan K
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