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Mac Boot Camp, part 3: Mac hardware, the early days

In part 3 of his Mac Boot Camp series, Larry Loeb takes a close look at Apple's earliest attempt to standardize software and hardware.

One of the Mac’s unique promises was that Apple was going to blend both hardware and software and tune them up in such a way that they would work together. If you bought a Mac, you bought a solution in both hardware and software. You didn’t have to buy MS-DOS or CP/M or OS-9 to load on top of its hardware (and then set that OS to the hardware that you actually had on board). Apple standardized the hardware to go with the software.
This article is part three in the "Mac Boot Camp" series by Larry Loeb. If you missed the first two articles or want to refresh your memory, here they are:
Mac Boot Camp, part 1: What’s a Mac program like? Mac Boot Camp, part 2: The managers
Since hardware capabilities mostly determine the software that can be made to run on that hardware, it seems like a good idea to look at Mac hardware over the past 15 years before reviewing software trends. There have been lots of configurations to confuse the unwary along the way (even though the vast number of configurations led to their cannibalizing of each other’s markets during Spindler’s reign at Apple).

In the Beginning
In the Beginning (1984), there was the 128K Mac. It had two DB-9 serial ports and a 16-bit address/32-bit internal bus 68000 running the show at 8Mhz. (Since this was eight times faster than the 1-MHz 6502 of the Apple II, it seemed an improvement at the time.) The mouse had its own port, as did the keyboard. Both were interfaced at the hardware level through a Rockwell 6522 Versatile Interface Adapter, which could generate an interrupt to the CPU. And your 400 KB floppy drive (all right, you could have two if you wanted to plug an external one into the port on the back of the machine) could hold both the Mac OS and the programs and files needed to run it. Surely, every developer—who was happy for the chance to be able to run on a Mac—was going to hand-optimize the machine code to fit.

Well, engineer Brian Howard and the boys sneaked one past Steve Jobs. It seemed that you could get the 128K up to 512K by replacing the RAM chips and cutting the lead of one resistor. A company called Levco soon started making the rounds at Mac shows, transforming your 128K into a “MonsterMac” and giving you a “hotter” 16 MHz 68000, if you really were a speed demon. Just bring along your machine to the show and they would change it while you waited. The fact that all this activity voided the Apple warranty was gleefully ignored by supplicants.

The Apple strategy
When the tang of solder wafted past the noses of Apple management, they realized that they had to make a more robust Mac—one that people could use better, one that people would actually buy. Sales for the 128K were somewhat “disappointing.” Early adopters were happy, but others who tried to use them for everyday tasks kept bumping their heads against the machine’s hardware limits. When you got onto a busy network and packets kept colliding with one another, AppleTalk—the software that you used over the serial ports for networking—wasn’t hitting the throughput that the developers promised. The hard drive that you could add to these machines had to run through the external floppy port, and it functioned (rather inefficiently) as a large 3.5-inch floppy drive.

Interim products were thrown hurriedly into the marketplace. The Mac 512 was a 128K machine with more memory. The next machine (the 512KE ) had 800 KB floppy drives (whoo hoo!) and a new 128K ROM, which would be used on the machine that followed the KE.

The Mac Plus, released in 1986, was Apple’s answer to all critics of the first Mac. It came with 1 MB of DRAM (though you could stuff in up to 4 MB just by plugging in more memory DIMMs), a SCSI port, and all the hardware that its predecessors had. (Although the external floppy drive connector disappeared, Apple felt that the reason for it had disappeared by then, too.) The SCSI port allowed the hard disk to run at its proper speed. Based on the NCR 5380 one-chip SCSI controller, the SCSI software went through several panic iterations at first. (It was rumored at the time that the developer responsible for the SCSI driver code—whose name was Eric—tested it on only one hard drive that happened to be lying around and that had a number of quirks to it. This story supposedly explained why the first versions of the software couldn’t do blind reads or writes.) Even better, you could run a LaserWriter through the newly tweaked AppleTalk network for the serial port, and you would still have enough room in the memory to keep more than one or two fonts active. It was hot for the time and turned the Mac’s reputation around. It was the first machine that businesspeople felt could do “real” work in a business environment.

Mac SE
What do you call a Mac Plus in a “dead lead” color case? The Mac SE. To be fair, this version of the Mac featured some improvements. It was the first Mac to use the four-wire Apple Desktop Bus (ADB) with which the mouse and keyboard could both connect (thus freeing up one serial port). It also had a “boxer” fan. This fan was (initially) the cause of numerous user complaints. It squeaked and made noise and generally drove people nuts. Legend has it that the fan (and the denial of a problem by Jean-Louis Gassee, who was head of Apple development at the time) drove one user to such distraction that she took her machine to Apple HQ, dumped it on Gassee's desk, and said, “Now do you hear it?” Apple finally replaced the boxer with a quieter cylindrical-shaped fan.

The SE was also the first Mac to feature an internal 20 MB hard disk (or another 800K floppy, if desired) and a bus socket that made upgrading processors or adding external complex hardware fairly simple—you just plugged in an interface card. The Euro-DIN 96-pin connector for the SE bus brought out all the CPU signals, as well as power and other internal timing signals.

All the machines that we’ve discussed so far fit the original Mac idea of “one machine for the rest of us.” Within certain parameters, you took what Apple told you to take. But the inevitable push for the customization of Macs was building and could not be ignored. In part 4 of this series, we’ll examine the hardware that Apple created as a response to this trend.

Larry Loeb has 20 years of computer journalism experience. He was Consulting Editor at the late, lamented BYTE magazine, he launched WebWeek, he ran the online Macintosh section of BIX (the BYTE Information eXchange), and he wrote numerous articles for many major computer magazines. Recently, he also wrote a book on Secure Electronic Transactions, the protocol endorsed by MasterCard and Visa that allows merchants, cardholders, and banks to work together over the Internet. For banter, tips, and general screaming, send Larry an e-mail .

The authors and editors have taken care in preparation of the content contained herein, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.
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