LC 475 doesnt recognize ibm 1gb

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Im trying to put in my ibm 1gb hard drive in my lc 475 but i cant boot off the cdrom when its plugged in but when i put the appple 160mb hd in it boots fine. Anyone know the reason why its doing that? And will 160mb be enough to install mac os 8 or do i need this 1gb to

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Macintosh128k's picture
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Re: LC 475 doesnt recognize ibm 1gb

Can you boot just from the CD-ROM with no hard drive connected?

if you can, but not with your 1gig drive connected it sounds like a SCSI termination problem,

I.e. try changing the ID of the CD drive, should have buttons on the back to change the devices ID number.

System folder under system 8 will take up about 100mb

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Re: LC 475 doesnt recognize ibm 1gb

Thanks for the info!

eeun's picture
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Re: LC 475 doesnt recognize ibm 1gb

The internal drive is usually ID 0. The CD-ROM drive was set to ID 2 or 3.
If the scsi ID settings aren't printed on the 1 GB drive (I can't remember) Google for the drive model number, and you'll likely find a site that shows the jumper positions.

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Re: LC 475 doesnt recognize ibm 1gb

Well i changed the id of the cd drive to 2 3 and 4 and had no luck starting with or without a hard drive connected. Why can i boot of the cd with the apple hd plugged in but not with the ibm or with no hd?9

eeun's picture
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Re: LC 475 doesnt recognize ibm 1gb

"scsi voodoo" was a popular term during the 68K era, and you're seeing why.

Quick guess? The default HD in the 475 may be terminated, which is allowing the 475 to use the external scsi device. If the IBM drive does not have the terminator jumpered, it would be equivalent to not having a drive installed, and in neither case would the CD-ROM be visible.
The older drives like the 475's built-in would have several removable resistor packs on the the scsi connector. The IBM you've got should just have a single jumper setting to enable termination.

Termination acts something like a shock absorber for scsi signals that can otherwise bounce around and prevent devices from being seen.

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Re: LC 475 doesnt recognize ibm 1gb

Okay so would I be able to fix this?

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Re: LC 475 doesnt recognize ibm 1gb

I enabled termination by closing jumper 6, and all the rest are open (the jumper is not on the other ones except 6) but I still can't get it to work.

eeun's picture
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Re: LC 475 doesnt recognize ibm 1gb

Probably not. There's likely nothing wrong with the drive (indicated by the same problem existing with or without the drive installed), and any replacement may also present the same problems.
Take a look at the IBM drive. On top of the drive should be a label near the power connector. It'll say "ID BIT 0, ID BIT 1" and so on. These tell you the settings for the jumpers that are on the underside of the drive, again near the power connector. ID BIT 0 means scsi ID 0, and that's where your first jumper should be if you're installing the drive in the 475.
There's probably another jumper positioned on UNIT ATTN. If it's there, it probably needs to be there. You could try moving it one over to the termination, but if it doesn't work for you, move it back and assume it's needed where it is.

The sixth jumper position is labeled "SCSI TERM", which represents the jumper for enabling termination. If it doesn't have a jumper in the sixth position, it probably needs one for it to be seen on that Mac.
You may be able to scavenge a jumper off the built-in drive, but note where it was positioned first so you can put it back after testing.
If you're desperate, improvise a jumper from a small piece of wire or paperclip and wedge it in with bunched up paper, tape, anything that'll keep it firmly against the pins and not fall off, until you can get a proper jumper.

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Re: LC 475 doesnt recognize ibm 1gb

I've uploaded a picture and I found the label with ID Bit 0 and all that. So I put the jumpers on the first and sixth pins.

http://s189.photobucket.com/albums/z249/austinramsay/?action=view&current=2011-04-03_12-49-36_673.jpg

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Re: LC 475 doesnt recognize ibm 1gb

Well, I made a tinfoil jumper for the 5th Jumper (Unit attention) and I have jumpers on the 1st (Bid ID 0) and sixth (termination). And I still can't get this to boot of the OS 8 cd with control option shift delete.

eeun's picture
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Re: LC 475 doesnt recognize ibm 1gb

Should be okay just holding down the c key to boot from CD. The 475 supports it.

And you may have just mis-typed, but it's cmd-opt-shift-delete.

cmd-opt-shift-delete bypasses the default drive - which if you're having pram problems is irrelevant - and searches from highest to lowest scsi ID, so if your hard drive has a higher ID than the CD-ROM, it may be trying to boot from that. The c key boot strictly looks for the CD-ROM drive.

I've dug out my 840av and tried to replicate some of your issues. I can't copy your exact setup, since I don't seem to have anymore external scsi cables, but I am getting similar issues with drives not mounting on the internal scsi chain, no matter the termination or ID. They show up in scsi probe, but won't mount.

One possibility (though I don't think I've encountered it before, so it may be so much ballyhoo) is they are formatted with a newer version of Apple's driver, and maybe it's not backward compatible with the older OS. I may have to unearth the beige G3 to test that theory.

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Re: LC 475 doesnt recognize ibm 1gb

Oops, typo! Yeah I've tried booting with C too, and I just can't get this thing to boot with this IBM hard drive. I just don't get it, and I've tried everything! But thanks for trying to help me so much.

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Re: LC 475 doesnt recognize ibm 1gb

Your best bet at this point might be to get hold of a Disk Tools floppy with a MacOS8 or Drive Setup, or a patched 7.5.3 Drive Setup that will handle generic scsi drives.
As per my post above, I found the 7.6 CD refused to see several drives I tested, though scsi probe saw them, but the OS 8 Drive Setup was able to see and intialize them. Turns out they were all FAT16 DOS formatted.

Booting from floppy without the CD-ROM drive connected will help determine if it's a bad drive, or a problem with the scsi chain.

There was a link above for getting a Mac floppy made from a PC, though getting hold of the Disk Tools floppy may be more of a challenge. Looks like a lot of the Gamba links no longer work.

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