Many more years ago than I care to admit, I took a C programming class in college. The computers in the university labs were all Macintosh Pluses, and nearly all of them had a single floppy drive.

(Photo for illustration: Tomas Martinez – Macintosh Plus with an external Hard Drive – URL)

Stepping into the wayback machine

The procedure for writing a program was something like this:

• Boot from a system floppy, then eject the disk.
• Swap in the Thin C disk, run the compiler, then eject the compiler disk.
• Insert the work floppy, load my source code, and continue programming.
• When it came time to compile, I was stuck in floppy-disk-swap purgatory.

It took between 10 and 20 minutes of disk swapping to compile even a simple program. And if I happened to fat-finger an extra semicolon somewhere in my program, the error of my ways was pointed out to me, and I got to start the whole disk-swapping process all over again. Tedious, yes. But there was light at the end of the tunnel.

There was a single Macintosh Plus in the lab that had a hard drive. Just one. It was always occupied, and I never managed to get my hands on it. But I was endlessly envious of the people who did. Compared with the floppy-only machines, that Plus seemed unbelievably fast.

Eventually the class ended. The computer science classes that followed mostly used PCs with hard drives or terminals connected to a Sun server. Depending on how many people were logged into the Sun, it could even feel slower than the Mac Plus.

Still, I always had a soft spot for that little beige machine.

Fast-forward a Few Decades

Eventually, I found a Macintosh Plus of my own, complete with the original box, accessories, and even the Apple stickers. Very cool. Of course, owning a vintage Mac isn’t the same thing as owning a working vintage Mac.

I got to work. I recapped the logic board, rebuilt and adjusted the power supply, serviced the floppy drive, replaced the infamous eject gear, and gave the plastics the requisite Arizona UV/peroxide treatment.

At that point, the little Plus was looking pretty good.

Now I finally had a chance to experience what that mythical hard-drive-equipped Mac Plus from my college days must have been like.

Well…

Not quite yet.

I connected an external BlueSCSI, which I had already gotten working on my Classic and SE, turned on my Plus and… no lights. No boot. Lone blinking icon.

BlueSCSI, Meet Macintosh Plus

I don’t admit defeat very often, and this time wasn’t going to be an exception. I managed to power the BlueSCSI from USB, but the Mac still refused to boot from it. Could it be an electrical issue? A little digging confirmed something I had vaguely remembered: the Macintosh Plus doesn’t provide SCSI termination power.

Apple actually designed the circuitry for it. They just never populated the diode at CR1. Without it, the Macintosh Plus doesn’t provide the termination power that some SCSI devices expect.

The fix is remarkably simple: install the diode Apple left out.

I soldered in a 1N5819 Schottky diode. The Schottky’s low forward-voltage drop makes it a good choice for this application, minimizing the voltage lost while supplying enough power to the SCSI bus. Five minutes later, the BlueSCSI was working on my Mac with no external USB power.

Progress!

Unfortunately, the Mac still wouldn’t boot, because of course it wouldn’t. More searching turned up another Macintosh Plus-specific requirement.. the BlueSCSI configuration file needs to specify that it’s dealing with a Plus:

[SCSI]
System=MacPlus

I added that, rebooted, still no luck. At this point, I was beginning to suspect that the Macintosh Plus was taking this personally. It turns out the Plus can be rather particular about the size and configuration of the SCSI drive it sees. The image I had originally been using simply wasn’t close enough to what the Plus expected.

So I went back to searching and found an appropriate disk image in the BlueSCSI image library on Mega. I downloaded it, copied it to my BlueSCSI Micro SD card, and renamed it:

• HD0_512-1GB-MacPlus-6+7.hda

After that, I removed the old HD0-iDontRememberTheName.hda file, which made it the first hard-drive image presented to the Mac, I powered it up. And… success! The Macintosh Plus booted immediately.

Finally, a Hard Drive

The installation was pretty minimal, so I used my Floppy Emu to add a few more programs and build out the system. Then, finally, I had it.. my Macintosh Plus, with a hard drive – just like the one I had been envious of in college all those years ago.

I fired up Thin C.

By modern standards, it is not exactly a speed demon. But compared with compiling C code from floppy disks, it feels absolutely blazing. No swapping disks. No waiting for the compiler to finish reading from a floppy. No swapping disks again.

And, best of all, if I accidentally type an extra semicolon, I don’t have to spend the next ten minutes listening to a floppy drive grind away while contemplating my life choices.

Was It Worth It?

Absolutely.

Looking back, I probably should have dragged myself out of bed and gone to the computer lab when it opened. Maybe then I could have grabbed that hard-drive-equipped Mac Plus before anyone else did.

But I’ll be honest.. thirty-something years later, I’m still not a morning person. Some things, apparently, are more difficult to fix than a Macintosh Plus.