Jump to content
armadsen

Mac Plus sees SCSI2HD but won't boot from it

Recommended Posts

I've got Mac Plus that I'm working on fixing up. It boots and runs just fine from floppies. I've got a SCSI2SD adapter plugged into the SCSI port in back. I've formatted the SD card using Lido 7.56 with a single 2GB (max size) partition at 3:1 interleaving. The Plus sees the SCSI2SD just fine and can read from and write to it. I installed System 6.0.8 on the SD card from a set of floppies. However, the machine will not boot from the SCSI2SD. It simply sits at the flashing disk screen forever.

 

I also have a Mac II which boots from the (same) SCSI2SD adapter and card without any trouble at all.

 

Has anyone seen this before? Any ideas about a possible cause? Why should the drive work fine when booted from a floppy but not be bootable itself?

 

Thanks!

Share this post


Link to post
Share on other sites

This may be a similar issue to what I experienced with my SCSI Zip drive. Formatted with lido 7.56, worked great for reading, writing and ejecting. Would not boot from it, despite a Macintosh SE booting from it with no issue.

 

Turns out the Plus was released before the final SCSI specs were. My understanding is that this leads to 99% SCSI support.

 

For me, the solution was to use Iomega's Zip Tools 4.2 to initialize the disk, and this made it bootable on the Plus.

 

In your case, I'd try using the patched version of Apple's drive setup that can work with any brand SCSI drive. Let it reinitialize the partition(s), and try it again.

 

Maybe someone else can provide more information on that patched Drive Setup, I don't know where to find it and haven't had to use it.

Share this post


Link to post
Share on other sites

Could be addressing issue,is it set to -0 or -1 or some other number? an partition size may be it.the Plus was fussy about that.

SYS folder should to be on -0- ID drive to boot I think.other members will have better input than me iam sure,good luck.

Share this post


Link to post
Share on other sites

Since the Plus doesn't have an internal disk he should be okay with anything other than 7. I'll have to double check what the scsi2sd comes defaulted at... Should be good on there.

 

Also, system folder can go on any partition, at any SCSI ID.

 

However, that partition size may play a part in the problem, good catch. What size SD card are you using?

Share this post


Link to post
Share on other sites

I've got Mac Plus that I'm working on fixing up. It boots and runs just fine from floppies. I've got a SCSI2SD adapter plugged into the SCSI port in back. I've formatted the SD card using Lido 7.56 with a single 2GB (max size) partition at 3:1 interleaving. The Plus sees the SCSI2SD just fine and can read from and write to it. I installed System 6.0.8 on the SD card from a set of floppies. However, the machine will not boot from the SCSI2SD. It simply sits at the flashing disk screen forever.

 

I also have a Mac II which boots from the (same) SCSI2SD adapter and card without any trouble at all.

 

Has anyone seen this before? Any ideas about a possible cause? Why should the drive work fine when booted from a floppy but not be bootable itself?

 

 

Sounds like a Plus problem? I have the exact same issue when using the SCSISD in a external HD20SC with my Plus, that it won’t boot, but it works just fine when used in my IIcx. I have tried Lido, HD SC Setup (patched), setting the vendor ID to Seagate etc. and different disk sizes.

Share this post


Link to post
Share on other sites

Here is a post from another thread here that may explain things: 

 

 

 

techfury90, on 12 Sept 2016 - 7:24 PM, said:
I was about to say, my first reaction was that the SCSI READ(10) command tops out at 2 TB. Hell, the Plus ROM doesn't even use READ(10), it uses READ(6), which is capped at 1 GB. You guys just don't notice that because the disk driver written during initialization and loaded during boot adds support for READ(10). I seriously doubt any of the higher bit LBA commands have any support whatsoever on OSes that old, for the reasons Gorgonops gives.

Edit: for extra trivia, READ(6) actually wasn't designed for LBA, it was designed for CHS geometry. It got retargeted to LBA when SASI became SCSI (yes, those commands date THAT far back).

 

Yea the plus only works with very specific disk drivers. I had a hell of a time getting a ZIP disk to boot but I eventually did, even in system 7. 

 

So try a >1GB volume size and see if it works. You may need that special disk driver to get the added SCSI support for READ(10)

Edited by techknight

Share this post


Link to post
Share on other sites

There are only a few disk drivers able to make HD bootable on the plus...

 

I think older "HD SC setup" as in system 6 install disks can, but the 7.3.5 can't! Sadly it's the only one to have been patched :( Maybe it is still possible to patch older versions to work with non apple drives?

 

On the zip side, you need to low level format zip disk with zip driver 4.2 or earlier.

 

I may have somewhere an old driver from my 44mb syquest driver, as far as I remember it allowed my catridges to boot the plus and more than that it may be able to format non removable devices (such as scsi2sd) too!

 

I'll look at it this evening and post a link ;)

Share this post


Link to post
Share on other sites

Remember you can also setup SCSI2SD to mimic an "authorized" drive, and then use the official HD SC setup from system 6.  I did this, but had problems initializing > 1 GB drives.  I think the version with 7.1 also had problems with larger drives, but 7.3.5 was good for anything. If initialization fails after a long period, decrease the disk size and try again.

Share this post


Link to post
Share on other sites

Thanks for all the replies, everyone. I had already set my SCSI2SD up to mimic a recognized drive, so the patched HD SC Setup isn't necessary. I'm running HD SC Setup from the 6.0.8 install disks as we speak and will report back.

 

I may have somewhere an old driver from my 44mb syquest driver, as far as I remember it allowed my catridges to boot the plus and more than that it may be able to format non removable devices (such as scsi2sd) too!

I'll look at it this evening and post a link ;)

 

 

Thanks! I'd love to try that if formatting with HD SC Setup doesn't work.

Share this post


Link to post
Share on other sites

As I mentioned unless the SCSI disk driver has the READ(10) patch, it wont work with anything >1GB. 

 

Also, you might want to take a look at your ROM version. There was a SCSI fix or two:

 

http://tech-insider.org/mac/research/acrobat/8803-f.pdf

 

If not, then patching the SCSI driver from the SE ROM over to the plus will fix it too. 

Edited by techknight

Share this post


Link to post
Share on other sites

 

Thanks, tjjq44. That formatted the disk just fine, but unfortunately did not make it bootable. I appreciate you helping, though.

 

As I mentioned unless the SCSI disk driver has the READ(10) patch, it wont work with anything >1GB. 

 

Also, you might want to take a look at your ROM version. There was a SCSI fix or two:

 

http://tech-insider.org/mac/research/acrobat/8803-f.pdf

 

If not, then patching the SCSI driver from the SE ROM over to the plus will fix it too. 

 

Based on the information here: http://mcosre.sourceforge.net/docs/rom_v.html, my Plus appears to have ROM v3 (checksum 4D1F8172).

 

How would one go about copying the SCSI driver from the SE ROM?

Edited by armadsen

Share this post


Link to post
Share on other sites

That is starting to sound like an expensive (both in cost and time) adventure.  Would it just be cheaper and easier to set it up with a FloppyEmu?  I don't have one (yet :) ), but my understanding is that it can emulate both a floppy drive as well as the HD-20 drive.  Can that HD-20 (if that is what it is called) image on the SD card have a size bigger than 20mb?(this question is directed to people that have worked with the FloppyEmu before)

 

Just some food for thought.  And with that setup, you could still use the SCSI2SD as well, just not as the boot volume.

Share this post


Link to post
Share on other sites

That is starting to sound like an expensive (both in cost and time) adventure.  Would it just be cheaper and easier to set it up with a FloppyEmu?  I don't have one (yet :) ), but my understanding is that it can emulate both a floppy drive as well as the HD-20 drive.  Can that HD-20 (if that is what it is called) image on the SD card have a size bigger than 20mb?(this question is directed to people that have worked with the FloppyEmu before)

 

Just some food for thought.  And with that setup, you could still use the SCSI2SD as well, just not as the boot volume.

 

I was thinking the exact same thing. I've been wanting an excuse to buy a FloppyEmu anyway.

 

Thanks all for the help and suggestions!

Share this post


Link to post
Share on other sites

I just joined this forum for the explicit reason that I can't get my scsi2sd set up (ver 5) to boot my 1MB Mac Plus either. 

 

I've tried plain HD SC Setup (after faking scsi2sd to appear to be an Apple drive), LIDO and both System 6.0.3 and 6.0.8.

 

Booting either of these 2 versions of System 6 still allows me to access the partition(s) on scsi2sd. I'm using a 512MB microSD, so it's not a >1GB problem.

 

It sounds like the Mac Plus will not boot from scsi2sd, is that the consensus here? I did try booting a regular SCSI drive on the Mac Plus and it worked. At least it got to the point where System 7.1 choked and complained about insufficient memory...!

 

I'm in the process of cleaning up a working SE/30. Will try the scsi2sd on that one next.

 

Thanks.

Share this post


Link to post
Share on other sites

I never did get the Mac Plus to boot from the SCSI2SD. I saw something regarding Mac Plus ROMs prior to version 3 having a bug where drives that issue unit attention on power up will cause the Mac to go into a reset loop and fail to boot. (See http://www.jagshouse.com/plusrom.html).The SCSI2SD configuration tool includes an option to enable/disable unit attention, but changing that setting didn't seem to make any difference on my Mac Plus.

 

For what it's worth, the FloppyEMU in HD20 mode works great with my Plus. Boots just fine.

Share this post


Link to post
Share on other sites

Maybe the SCSI2SD doesn't meet exactely the real old HD specs... As anyone asked the developpers to find a solution?

 

A trick to get around the problem (with system 6 only) is to boot from a floppy, then double click the finder file from the HD with command & option key pressed. Then, until next reboot/shutdown, the startup disc will remain the HD :) (system software versions must be identical on floppy and HD)

Share this post


Link to post
Share on other sites

That's a neat trick. I'll try it out.

 

At the least, it will save some grinding on the boot drive: I have only 1MB and it looks like parts of the OS gets reloaded every now and then.

Share this post


Link to post
Share on other sites

Armadsen, that sounds like the same symptoms of my Plus when I try to boot it with a Zip disk NOT formatted with Zip Tools 4.2.

 

This is almost certainly down to the odd SCSI implementation used in the Plus, unfortunately. I'd say a FloppyEMU or ROM-Inator are the ways to go with this machine. I opted for the ROM-inator. Required a little construction, but was cheap and gave me a bootable ROM disk (that you can actually write to from the Plus while it is running... I wish the ROM-inator II had that ability in the SE/30).

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×