Macintosh Plus Oddness

[just.in.time]

I have a Mac Plus with 4mb ram installed that is exhibiting some weird behavior.  When I try to boot it up using a SCSI disk drive with either 6.0.8 or 7.1 on 100mb disks I see the smiling mac, then a quick reboot (think 1 second span), and the smiling mac is back, rinse and repeat endlessly.

Initially I thought the disks had become corrupt.  Using the same Zip drive, I recreated both disks using an SE, tested that they started the SE (also with 4mb ram), everything checked out.

Back on the Plus, same symptoms.  I tried two different Zip drives, two SCSI cables, verified termination switch on Zip drives, still no go.

Mac Plus WILL boot with a floppy that has a copy of 6.0.8.  So I think the RAM should be good.  

Cleaned RAM contacts with rubbing alcohol and a q-tip anyways.  Still no change.

Thinking it was a low voltage problem, I tried the external 800k Apple disk drive I have (expecting it to fail in the same way if there was a low voltage scenario, since it is bus powered).  Worked great.  Also, display is bright and sharp.  So that idea is mostly out the window.

Any ideas?  Also, should be noted that this exact setup worked maybe 6 weeks ago.  I could try burning a System 7 startup CD, and trying the SCSI AppleCD 600e with it to see if everything SCSI is bad, however I tend to have bad luck creating bootable CDs.

I'm just about out of ideas.

 

[tjjq44]

Which version of the iomega driver did you use to format your zip disk? To boot a Plus, you need to downgrade to 4.2 or less, 5 or newer aren't fully compatible.

You can see the version when you "get info" from the disk in the finder

 

[just.in.time]

I want to say that my SE is running 4.2 for that reason, but I'll double check.  The disks were actually formatted by Lido though, not the Finder.  Would that make a difference?

 

[Elfen]

Where did you get both Systems? Using the copy that is for the SE will not always work with the Plus because of the added or changed hardware these two machines have. You wold have to get the "original" install disks and make it on the Plus for it to work. Making it on the SE and then transferring to the Plus will not work.

 

[just.in.time]

Thank you Elfen.  Yes, they are both duplicated system folders from the Mac SE (FDHD if it matters).  I can try copying over the system folders from the system 7.0 install disks to a blank Zip disk.  I could have sworn that those exact Zip disks had been used on this very Plus, with the same Zip drive, cables, etc less that 2 months ago, but I could be mistaken.

I will try creating a fresh Zip disk from the 7.0 install images, and verify that the Iomega driver on the SE is 4.2.  Additionally, this disk will be formatted from the Special menu instead of Lido.  Will report back in a few hours.

 

[just.in.time]

Unfortunately that experiment failed.

I used the Macintosh SE to install System 7.1 to the Zip disk.  I did a custom install, selecting "Install software for any Macintosh" (as opposed to "Install software for this Macintosh," "Minimal Install for any Macintosh," and "Minimal install for this macintosh).

Still does the fast Smiley-Mac boot loop.  It never ejects the Zip disk.  In the past when I have tried booting with a bad disk it will typically eject it upon boot failure.  Any other ideas?

... I feel like this will end up being capacitors, somehow.

 

[tjjq44]

Capacitors? Maybe on the analog board but You'd have more serious symptoms in this case (floppy loading erratically, strange display...). On the logic board there isn't any capacitor to replace in this machine.

Install this on your SE and reformat your zip disk with it

http://tjjq.free.fr/mac/zipmac42.hqx

 

[just.in.time]

Thank you, I will try this later today!

 

[Elfen]

On all System 6 and most System 7, there was a System Build option for "System for this Mac" and "System for ANY Mac." Use the latter for building a Bootable Zip Disk for the Plus and put the Zip Drive drivers into the Extensions Folder (in System 7).

The System for any Mac, trims out a lot of things for a basic system but this would be good for a Mac Plus as all it needs is just the Basic OS. This "Any mac' was intended for nay mac in the Mac II series and the Classic B/W series that included the 512Ke to the SE/30 and up to the LC II in the LC Series. Things get a little funky after System 7.1, however.

This should work for you.

EDIT: How much RAM is in the Plus? System 7 needs 4mb in the Plus & SE (and any other Mac) as a minimum; thing is 4mb is the Max the Plus and SE can hold. And System 7 runs slow on both the SE and the Plus.

 

[just.in.time]

Tjjq44, I installed ZipTools 4.2 to my SE running 7.1.  Formatted with the Zip Tools app, and used the installer to install a universal system folder for 7.1 to the Zip drive.  Like always, tested with the SE and it worked great.  Moved over to the Plus... and we have success!!!       For whatever reason, the Plus is definitely more picky about how the Zip disk is formatted than the SE FDHD (and I'm assuming later machines).  Thank you so much.

Anyone that reads this after having run into the same issue: Lido utility couldn't do it, Lido extension and Special -> Erase Disk... couldn't do it, Iomega 4.2 Guest Driver and Special -> Erase Disk... couldn't do it.  Keep in mind all these disks would boot my SE FDHD with no issue for 6.0.8, 7.1, and 7.5.  However none worked on my Plus.  I had to install the Zip Tools 4.2 software (see above, post #7), and use the application to format the Zip disk.  Just for good measure, I let it perform a surface scan at the same time.

Elfen, both systems have 4mb of RAM.  Previously I had been installing a universal system on the Zip disk, but still getting the reboot loop issue.  On the SE, I find 7.1 to be my favorite OS.  It gives up just a little speed compared to 6.0.8 for so much more modern of a feel, compatibility, and feature set.  Even with Background and After Dark 2.something installed, I still have ~2.7mb free of ram... Or roughly 270% more memory available for whatever than it had the first 11 years I owned it (2005-2016) and ran 6.0.8.  Now 7.5 on the other hand, didn't seem to add as much value compared to the performance hit and increased RAM usage relative to 7.1.  I quickly hopped back down to 7.1 and installed SuperClock.  This setup is easily one of my most favorite Mac systems of all time.  Nothing more relaxing than playing a game of Shufflepuck Cafe against the easily defeated robot just before calling it a night.  Anyways, this became a ramble, but in my experience 7.1 performs adequately on an SE with 4mb ram and a not-the-miniscribe 80mb hard drive. 

 

[tjjq44]

Glad to hear this worked, but I'm not surprised cause I've already had this issue many years ago

On my compact macs I always have 2 system folders (6.0.7 & 7.1) on my startup disks. I just isolate the system file I don't use in a subfolder and open/close the "good" system folder to bless it That gives me the choice between flexibility and rapidity, in addition I put some enablers on my 7.1 system folder in order to boot any mac in my collection!

 

[tjjq44]

...For whatever reason, the Plus is definitely more picky about how the Zip disk is formatted than the SE FDHD...

From Wikipedia: "The SCSI implementation of the Plus was engineered shortly before the initial SCSI spec was finalized and, as such, is not 100% SCSI-compliant."

To my mind, the plus is able to manage SCSI devices quite straight away, but some features had to be "invented/adapted" by apple since the specs weren't finalized... the boot detection may belong to these! Far after the release of the Plus, media manufacturers continued to keep compatibility with it in patching their drivers so every mac including the plus could boot from their drives... but dropped support after a while, that could explain why any formatting tool except iomega driver <= 4.2 fails to make the zip100 fully compatible with the plus (in this case: make it boot).

When I got my Plus in 1997 (My 2nd own mac & I was 17), I frequently borrowed my father's syquest 44 catridge reader to use with it. The driver utility provided was from 1993 and that's probably why I've never had any problem in booting my Plus with these catridges

 

[Paralel]

How the Plus handles SCSI really depends on the ROM version. Version 3 handles it according to spec as far as I know.

 

[just.in.time]

That is some interesting history regarding the Plus and SCSI timeline.  The logo above the SCSI port on this particular Plus is definitely not the standard SCSI logo, but resembles the Mac OS hard drive icon instead.  It is also labeled as "Macintosh Plus 1mb" on the back sticker.  So this would be a 1986 model before they changed to platinum casing?  Just going with what Wikipedia is telling me.  How would I see what ROM I have, just for curiosity?

 

[Paralel]

The easiest way to tell ROM 01 from ROM 02 is to try to boot the system with a SCSI device hooked up, but powered off. If its ROM 01, it won't boot, it will just hang. If its ROM 02, it will boot. ROM 02 was specifically implemented to deal with that issue. ROM 03 was introduced with the Platinum case model and was meant to address SCSI bugs and bring it in line with the final SCSI 1 specs.

 

[tjjq44]

Even if apple modified the rom twice, there may still be hardware limitations (scsi chip) they couldn't avoid... If not, what could explain the zip 100 can boot any mac (whatever the formatting tool used) but the plus (unless formatted with iomega driver 4.2 or less)?

PS: my mac plus runs on rom v3 (loud harmonicas)

 

[just.in.time]

I gave the power on test a try.  Two Zip Drives attached, with IDs 5 and 6, and 6 having the terminator switch set to "on."  Attempted to boot from the Zip disk in drive id 5.  No "hangs" per say, just the endless disk with flashing question mark.  Like the powered on Zip drive didn't even exist.  I'm guessing that means ROM 1.  Neat piece of info to know  .