Classic mac fun (and some questions) (continued...)

joe lobocki jlobocki at
Fri Jun 19 09:42:45 CDT 2009

I will state this: do not buy any other parts for the machine until you've
swapped or replaced ram. reason being, it took me to replacing a
motherboard, power supply, floppy drive, and hard drive in a Mac SE, and
several days of wasted time, just to one day discover that I had bad RAM in
my machine, and that was causing the floppy to act erratic, the hard drive
not to detect in hd setup, the computer would stall during OS install. sad
macs, from what i've seen, half the time are ram issues.

On Thu, Jun 18, 2009 at 10:46 AM, Brian Lanning <brianlanning at>wrote:

> On Thu, Jun 18, 2009 at 10:36 AM, Jeff Walther<trag at> wrote:
> > I would check along the lines that Doc suggested.  Some times Apple's
> "bus
> > failure" means a SCSI bus failure.
> >
> > Make sure that the SCSI chain is properly terminated.  If you're using
> > internal and external devices, confirm that both ends are terminated
> > properly and neither end is double terminated.   Check the SCSI IDs being
> > used by all devices on the chain.
> >
> > Go ahead and just pull the SIMMs on the motherboard.  There's 4 MB on the
> > logic board and that should be enough to boot from, or if it gets that
> > far, you'll get a message about lack of memory, which is further than
> > you're getting now.  If that happens, hold down the shift key during boot
> > to not load extensions.  That will often save enough memory to allow
> > booting in 4 MB.
> >
> > I don't remember the beginning of this thread, but isn't there a
> suspicion
> > that the internal hard drive is malfunctioning?   Disconnect the internal
> > hard drive completely, and only connect the CD-ROM drive.  That will
> > simplify your SCSI chain, and eliminate electronic babbling from the hard
> > drive as a possibility.
> >
> > So, basically, pull the RAM and all SCSI devices other than the CDROM,
> > make sure the CD-ROM drive is terminated and set to some ID other than 7
> > (SCSI ID 3 is traditional for CD-ROMs in a Mac) and try that.   Also
> > double check the cable you're using and try a different one if the first
> > does not work.
> >
> > Once you get a successful boot, you can try adding things back in.
> Thanks, I'll give it a shot.  I'm not sure about the internal
> termination situation.  This is just a jumper on the hard drive,
> right?  I think the 3.5" half height drives didn't use resistor packs.
>  I know there's no separate terminator on the ribbon cable inside.
> I'll swap out the cable and terminator.
> As far as I know, the hard drive is ok.
> I ordered another OS cd which should be here shortly.  This one is a
> new one so it shouldn't be suspect.
> I supposed it's possible that the cdrom drive could be bad.  I ordered
> it used from ebay.  It's been behaving exactly as expected though so I
> believe it's ok.
> brian

More information about the cctech mailing list