System 7.5.5 on Mac Plus and HD20

[el_jeffe]

I apologize if this has already been posted but I can't seem to find exactly what I'm looking for. I recall reading somewhere that HD20 support was dropped with system 7. If anyone can shed some light on that I would appreciate it.

Also the Mac Plus is supposed to support up to system 7.5.5. I'm assuming one would need to have a SCSI drive(size?) instead of the HD20 and the full upgrade to 4MB RAM. Curious to know how one would have installed since the Plus only has the 800k drive but most system 7 versions came on HD floppies. I realize it's not really recommended to run that version of software on the Plus, just interested in how it would have been done back then since it's 'technically' possible.

 

[BadGoldEagle]

External CD drive?

 

[ArmorAlley]

First of all, upgrade the RAM on the Plus to 4MB, if you can. It gives you the option of using a RAM disk, which is very useful (and much faster than any HD).

Should you want to run System 7.5.5 on your Plus, I wouldn't bother looking for 30+ 800K floppy images. Instead, invest in some external SCSI devices, along the appropriate cables and terminator. Get a CD-ROM, a hard-drive and a Zip-drive. You can fit 7 devices on the SCSI chain and the last device on the chain must be terminated. No other device in between may be terminated. The Zip-drive has a termination option on it but it is handy as the first device because it comes with a 25-pin SCSI port. The other devices will most probably be the big blue 50-pin Centronics ports. For the Zip-drive, you'll need the Iomega Driver 4.2. This works under System 6, which really, is the only version of the SSW that you should be using (but, then again, I'm running Mac OS 8.1 on my IIfx, so I'm not in much of a position to be saying anything of this sort...). There are any number of control panels and applications that will allow you to mount SCSI drives. Don't get too new a CD-ROM drive or you won't be able to mount it easily. The Apple CD 300 or 600 should be grand.

Anyway, once you got all of your SCSI devices mounted on your Plus, go to the Macintosh Garden, look up Mac OS 7 and there is surely an ISO of System 7.5.3 on it. Burn this onto a CD on your modern machine and you should be able to boot with it on your Plus. If your modern machine is a PC, get yourself a copy of HPV-Explorer and this will allow you to write to HFS volumes. You'll either need a SCSI card in your PC, in which case you can use your SCSI zip drive, or a USB zip drive. I'm not altogether sure what to do if your modern machine is a Mac. Mac OS X 10.12 is not at all friendly to the past. HPV- Explorer and Mini V-Mac may exist for it. I just don't know. One option would be to either to get a PCI-Power-PC with serial ports and create a bridge mac with you modern Mac (ethernet from modern mac to PPC, AppleTalk over a serial connection from the PPC to the Plus), or get a G4, install Mac OS 9 *and* Mac OS X 10.4 (Tiger) on it and use the browser TenFourFox to download the files that you need. Classilla under Mac OS 9 will also do for the Macintosh Garden. After you've booted back into Mac OS 9, you can easily copy files to a zip disk or burn them onto a CD for your Plus. One can boot the Plus from zip-disks but you need to avoid putting the disks formatted on your Plus into more modern Macs. The Iomega driver from version 5 onwards updates the driver on the disk and prevents it from being able to boot the Plus. Have one disk for booting the Plus (and nothing else) and another disk for file-transfer. Of course, if your G4 has a SCSI card, then you can put the external hard drive on the G4's SCSI chain (again, making sure that it is terminated) and simply transfer files across that way.

Another recommendation is to go to Jag's House on da Net and order his CD with System 6 goodies on it. This will save a lot of downloading for you.

 

[Macdrone]

HD20 runs system 7.0.1 just fine.  System 7.5.5 may run but my guess is it would be pretty slow.

 

[Macdrone]

I have system 7 on my plus now with 4 megs of ram.

 

[el_jeffe]

Thanks, everyone! I'll see what equipment I can round up and try to give this a go. Would it have been this complex for someone in the early 90's to get installed on a Plus? I would assume Apple had some officially supported way to do it since it would technically run. I may be over thinking it but I would think that a lot of people had a stock setup or maybe only did an HD20 or 4MB upgrade. However, one could also argue that back in those days there were a lot more upgrade options to extend the life of a machine vs buying something new(at least on the PC side, look at what this guy did to his IBM)

http://orignialbeast.blogspot.com/2014/11/vintage-ibm-pcxt-big-blue-beast.html

 

[Macdrone]

System 7.5 had a requirement of 4 megs of ram, so to run on a plus with an HD20 in 1994, some 6 years after the Plus was released there was no other way to put it on there.  System 7 could use much less ram on boot.  The LC in 1994 that came with 7.5 had 4 meg on board so it was a non issue.  I am pretty sure it was system 7.5 that made Apple finally retire hardware support.  

 

[ArmorAlley]

We had Mac Pluses in our university for student use in the late eighties - early nineties. They had no external hard-drive. System 6 was so small that you could easily fit MacWrite and your files on to one 800K floppy. For those who had to use something big like Excel 2 or so, then there was a *lot* of disk swapping. This was part of the reason that I was very happy to learn about RAM disks. If the Plus had 4MB of RAM (or even 2.5MB RAM), then you could create a virtual drive, load the contents of a couple of floppies onto it and work without the incessant floppy swapping.

While you could run System 7.1 on the Plus, I never really saw it done because it brought no benefit. The Plus is a System 6 machine through-and-through. And System 7.1 was available on 15 800k floppies, if I remember correctly.

 

[CharlieFrown]

is there any specific reason to run System 7.5.5 on slow as molasses 68000 processor? I thought operating systems written in assembler (up to 6.0.8 I guess) were definitely faster and nicer to use than the versions released after transition to object language. Just my two cents.

 

[Macdrone]

I run 7.0.1 as I used it for AOL back in the day as a spare until I got a powermac.  Modified a geoport external modem to get power from the keyboard and away I went.  You have not lived until you were on AOL in black and white.

 

[Bugsi]

I realize this is a necro-thread, but I feel like I'm in a unique position to shed some light on the answer to this question.
I was on the installer QA team for "Unity", System 7.5.3 revision 2, and I was personally assigned the task of testing the installer on the Mac Plus. While the OP's question was related to System 7.5.5, the challenges with 7.5.5 are going to be at least as difficult as the challenges with 7.5.3r2, so I'll address the problem of installing 7.5.3r2, and those should translate to similar or identical issues with 7.5.5. (Disclaimer: I've never installed 7.5.5 on a Plus, that I can recall.)

Of all the Macs supported by 7.5.3r2, the Plus was particularly difficult to install it on, because of a requirement that the 7.5.3r2 installer be launched from a minimum of System 7.5. Someone indicated above that 7.5 requires 4 megs of RAM, and I have no reason to not believe that. In modern times, if you own a Mac Plus, there's no reason why you shouldn't have 4 megs of RAM in it, so that shouldn't be a problem. The problem with System 7.5, of course, is that a bootable System 7.5 install will not fit on an 800K floppy disk. So: To run the 7.5.3r2 installer, your Mac Plus cannot be booted from a floppy disk.

I honestly can't speak for the HD20 external hard drive. The bottom line that Apple determined was an acceptable limitation was: To install on a Mac Plus, you needed two external SCSI hard drives, or possibly two partitions on one external hard drive. You needed one SCSI external drive to boot at a minimum System 7.5, so you could run the 7.5.3r2 installer to install that OS on the other SCSI external drive. I'm going to presume that's the same requirement to install 7.5.5.

The way we did it, in general, was to use another, newer Mac, like an SE/30, LCIII, or Mac II or whatever, to use the 7.5.3r2 installer to create a univeral install on an external SCSI hard drive. The universal install just installed EVERYTHING, all the software components for both PPC and 68K Macs, all the model-specific components; everything. As a result, it would boot any supported Mac. It was a magic bullet for a problem like installing on a Mac Plus. You had to be careful to get your dual external SCSI hard drives terminated correctly, but once you did, you booted off the Universal OS on the external, then launched your 7.5.3r2 installer, which could be on the Universal boot drive (very convenient) or could be on an external CD drive (more complex for the SCSI chain), or it could be on floppies (which are 1.4Mb so won't work on a Plus). You'd select the second external drive as your target for install, and let it rip. You could just use a bootable System 7.5 on the boot disk. You also needed the installer, and one way to do that was to copy the CD files to the bootable external, by using a better/newer Mac with a CD drive to read the CD and copy the installer to the bootable external SCSI drive. The QA testers were generally each assigned an external hard drive, and we'd typically install a Universal 7.5.3r2 install to use as the boot system, and copy the CD contents to the drive to use as the installer. You could take that to any Mac and have everything you need to install, but the Mac Plus and dual-flopy-drive SE additionally needed an external target drive to install on.

Another interesting note: The 7.5.3r2 installer can run over a LocalTalk network. It's SUPER slow, but it will work. You can connect to another Mac that has the installer on it, and launch the installer that lives on the remote network computer. The Mac Plus supports LocalTalk, so in theory that should work, but it didn't, and I wrote up that bug. Apple decided to not fix that bug (or decided it couldn't be fixed; it might have been some unique limitation on the Mac Plus) but the result is that you can't install on the Plus using an installer over a LocalTalk network. That's not really a major loss because even if it did work, it would take a REALLY long time.

In conclusion, the best way to install 7.5.3r2 on a Plus, and by extension 7.5.5, is to use a newer/better Mac to set up an external bootable drive with at least System 7.5, but more commonly a universal install of 7.5.3r2, along with the 7.5.3r2 or 7.5.5 installer files or images, and also connect an external SCSI target drive, with proper termination. Separate partitions could be used on a single drive, if you wanted to do that instead.) Boot off 7.5 or newer, launch the 7.5.3r2 or 7.5.5 installer, select the target disk, and install away. Once you're installed and shut down, you can remove the boot/installer drive, leaving just the target drive (with proper termination) and use that with your Mac Plus.

I have the retail 7.5.3r2 installer CD, and I have a Mac Plus that I use with BlueSCSI. At some point in the near future I'll get around to experimenting with this more, and I'll update with anything I find with 7.5.3r2 or 7.5.5, but as previously noted by others, a Mac Plus is really at its best with System 6.0.8.

 

[Iesca]

Thank you for your insight! I wonder if the HD 20 is verboten because it's treated as a floppy disk of sorts?

As for 7.5.x, it is supposed to be quite unwieldy on a Plus from what I gather. I have found a bit of a happy medium myself using 7.0, but of course as you say System 6 is best.

 

[Phipli]

Would it have been this complex for someone in the early 90's to get installed on a Plus?

CD drives were fairly common by the time 7.5 was released in 94. You can also share disks over a network so how I would expect it to happen BITD (but not recommended because 7.0.1 is really the newest I'd go on a Plus) would be...

Upgrade to 4MB of RAM and an external 40MB SCSI HD (stolen from another machine I'd upgraded)
Share the 7.5.* install CD over localtalk from my IIvx
Boot the Plus from a 800k floppy with networking, probably 7.0.1.
Mount the network share CD and run the installer... Wait hours...

Restart in 7.5.*.

Edit - just read @Bugsi's comment! Seems like I'd have wasted my time with an attempted localtalk install. Issue is my oldest computer back then was an SE

Could you have run the installer from an external CD? Or was the issue that the installer wouldn't run at all?

I've helped someone with issues running installers on an SE/30 with only a tiny amount of RAM previously (4MB on a 7.1 machine I think). The 7.5 installer didn't fit in RAM unless you booted with extensions off.

 

[Phipli]

As for 7.5.x, it is supposed to be quite unwieldy on a Plus from what I gather. I have found a bit of a happy medium myself using 7.0, but of course as you say System 6 is best.

I dual boot 6.0.7 and 7.1 on my SE. 7.0.1 would be more lightweight, but you can get AppleScript working on 7.1.

6.0.8 and 7.0.1 or 7.1 combined give the choice of speed and compatibility

 

[Iesca]

Exactly!

 

[Phipli]

Exactly!

I missed out on 6 as a kid. When I got a the SE as a hand me down it already had 7.0.1 on it. Didn't think to downgrade it, but I probably should have.

No forum to tell me back then at least, not that I could connect to

 

[Mk.558]

[wonderful wall of text]

Great story. Can you tell us more? More stories, more we'd like to know about.

The easiest way in my opinion to install 7.5.3 on a Plus (not that I'd recommend that, it's slooow even on a SE/30, "meh" on a Quadra 700, I'd rather just use 7.1) would be to just build it out on a mini vMac system, pack it all up into an archive and shuffle it over LocalTalk. Bless the system folder and you're done.

If you wanted to do it without a network, you can use a 7.0.1/7.1 Disk Tools disk. These were available in 800KiB form. You'd then have to play the floppy swappy game unless you have 2 floppy disk drives (which, if you have a Plus, you'd want), and install 7.5.3 that way onto a local disk. The Universal install is like 36MB (yikes!), the Minimal Install for this Macintosh is like 875KiB, the standard install is like 8.5MiB.

Agreed strongly with Phipli about 6.0.8 and 7.1/7.0.1. I would like to use System 6 more (just so FAST) but System 7 is way more useful.