iBmac - International Business Macintosh

At first, these look like two ordinary IBM PS/2 Model 25 computers...


Two Model 25's


...but switch them on and...

sorry- it's really a visual gag


still the same 25's


...one of these things is not like the others.






Welcome to International Business Macintosh! ("iBmac")


iBmac





Well, here's my customized Mac.

There's a subset of the Macintosh user community which seems to feel that the Color Classic represents the 'ideal' all-in-one Mac, and some of these folks have gone through great lengths to upgrade their CC's through various means, including replacing the motherboard with that of a more powerful Mac.

Not that there's anything wrong with that, but somehow it didn't seem like 'my' sort of modification project.

Then one day, after noticing another PS/2 Model 25 in a thrift store, I suddenly felt I had my project.

Remember the PS/2 25? It was IBM's first (and perhaps only) real attempt at an all-in-one desktop machine for the home market. [I'm not counting the IBM PC Portable, which was primarily designed as a business 'luggable'] It was introduced in 1987 as the new low-end model in the PS/2 line. At the time, I worked in the computing center at the university I attended, and while it didn't seem to be a particularly popular machine, I thought it was kind of a 'cute' design (though quite underpowered, even for the late 80's). I'm sure IBM intended it to appeal to potential Macintosh buyers and compete with the Mac Plus and SE models. In keeping with the 'compact' theme, you could buy your PS/2 25 with a matching Space-Saving Keyboard (shown above). IBM even offered a padded carrying case for the Model 25 that was similar in design to the cases sold for the compact Macs.

So, since the PS/2 25 was, in many respects, what a Macintosh would look like if IBM made it, I thought it'd be fun to take the concept full-circle and turn one "back" into a Macintosh, as it were. :-)

[...Besides, I feel that the Color Classic design is a bit overrated... but that's just me.]

The PS/2 25 I modified for this project is one that I've had in storage for a few years, and which I had long ago 'upgraded' to a 25-286 by replacing the factory motherboard and drives with those from a discarded 30-286. Since it was no longer 'factory original' anyway, I didn't feel too bad about going another step with it. :-) [By the way, evidently, most PS/2 25's were sold with the monochrome monitor; both of mine are the color version.]

I used an LC form-factor motherboard for my iBmac [specifically, a Performa 476 (Quadra 605) board], as they're inexpensive, easy to handle, and juuuust fit in the width of the PS/2's base.

I chose an old auto-inject floppy drive (swiped from an LC II) instead of the more modern manual-inject style, because (a) I think the auto-inject ones are cooler, and (b) they're a lot like the old PS/2 floppy drives in that they don't have a spring-loaded cover for the drive slot, so they should look/work better with the original PS/2 drive bezel.

In the future, I'll install the eject button from an IBM drive along with a linkage so that pressing the button will actually eject the disk. [ A Mac with a floppy eject button?? Who'd a thunk it..? ] Also, I don't seem to have any spare blank or HD bezels for these 'tall' PS/2 drive bays, so I had to use a floppy bezel over the hard drive (or should I call it a "fixed disk" to maintain the IBM parlance..?) For some reason, I have some extra HD bezels for the low-profile PS/2's (i.e. the Model 30), but not for the other machines...

Also in the future, I'll have to cut a new rear panel for the iBmac. For now, I merely removed the original panel, thus leaving a large open space in the back. This panel had the cut-outs for the I/O ports and the IBM's two expansion slots. It also is what (with two screws) latches the bottom 'carriage' to the monitor/power supply section, so for now the thing is held together with a piece of wire.

At some point I may include some construction notes for those who might be curious. In particular, constructing a cable to adapt the header plug for the built-in monitor to a Mac-style 15-pin video connector may present a problem if you can't determine the pin-out of the original cable. One surprisingly tricky bit, BTW, was getting the Mac floppy drive mounted in the cabinet so that it would line up properly with the slot in the front bezel.




BACKGROUND: I'm not really a Mac enthusiast in the usual sense. All of my primary computers have been from the IBM world since the late 80's. My first 'real' computer was an Apple //e (bought immediately after it was introduced), and I still have a soft spot for the ][-series, but had never cared much for the closed Mac design. However, I started using Macs occasionally at work a few years ago, and shortly thereafter I bought an old SE/30 on a whim. I've had lots of fun with the Macs I've aquired since then, and have learned a lot about them (many thanks to the active Mac community on the web; especially Low End Mac), but I'm still really a PC person (Sorry!). While I feel that both Macs and 'Wintel' machines have their own flaws (yes, Macs aren't perfect either) and benefits, there's certainly a place for both in the world.

BTW, Dan Knight (the person who runs Low End Mac) once ran an April Fools joke in which he changed the focus of the home page to "Low End Win". Actually, I'd almost seriously consider starting something like that for real. I mean, why not? ...Though I might call it "Low End Dos" instead. :-)

Speaking of which, you may notice that in the images above, yes, that is Windows 3.0, and yes, it's running on a stock (XT-class) 8086 PS/2 Model 25 with 640k main memory. The reason it appears in monochrome is due to the limitations of the built-in MCGA video of the Model 25 (and 30). For those of you who don't remember, MCGA was sort of a crippled VGA with only 64k of VRAM and minus the EGA emulation modes. This let you use the CGA emulation modes, plus the then-popular 320x200 256-color VGA graphics mode, plus 640x480 in 2 colors (B&W), plus most of the VGA text modes. BTW, of course, Win 3.0 runs quite sluggishly on this machine and is as such an almost pointless exercise in futility, but it's kinda fun in that it's the last version of Windows that can actually run on an XT-class computer. :-) Of course, most applications for Win 3.0 won't run on an XT (one very notable exception being MS Word for Windows 1.1), but, eh, it's just silly fun-- and that's the whole point.


Oh, and by the way, here are a few more pictures of my iBmac.



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Last Modified 08/11/00 / Contents Copyright © 2000 by Martin (Marty) Kuhn / mkuhn@rwhirled.com