Cassie Heart
@cassie
Execution and well-conceived integration are a mandatory minimum of realizing the potential of new innovations. Grab a coffee (or hot chocolate if you're @greg), sit back, and relax, we're going on a deep dive.
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Cassie Heart
@cassie
The Apple ][ is frequently hailed as one of the major milestones in personal computers. Not only did it make home computing more accessible than ever, it delivered many things we now take for granted that were incredible technological achievements for the time. Did you catch them in the picture above?
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Cassie Heart
@cassie
Let's look at an example of what others in the industry were offering to help demonstrate the difference: The Commodore PET. See the difference now? The Apple ][ could do color - something no other personal computer had been doing yet. The Apple ][ had floppy disks, faster and at greater capacity than any other. How?
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Cassie Heart
@cassie
At the time, video signals for home computers utilized NTSC composite video, the kind that worked with television monitors. These sets supported color through chrominance subcarrier frequency modulation - a technique that at the time typically required expensive chips to support.
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Cassie Heart
@cassie
But supporting limited colors could be achieved cheaply, if you could get the timing right, by emitting the signals in a particular way. Wozniak was predictably nerdsniped by this, and used this trick with the MOS 6502 and its timing set to 1.023 MHz, 2/7 of the NTSC color subcarrier rate.
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Cassie Heart
@cassie
The integration of controlled timing from the deepest part of the hardware down to the software unlocked color displays for home users, while its competitor, the PET, using the exact same chip, could not do this. But the division runs deeper. A sentiment was growing that floppy disks were needed for non-hobbyist PCs.
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Cassie Heart
@cassie
Woz stood up to the challenge again, this time, taking the raw hardware physically controlling the disk, and augmenting it with a cheaper software and timing-driven approach, reducing the overall chips in use (and cost, saving Apple >$300 per drive), while simultaneously making it faster and able to store more data.
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Cassie Heart
@cassie
Commodore's PET disk drive design ultimately required two processors on the scale of the Apple ]['s main central processing unit just to make it function, and for all that expense, still couldn't display color.
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Steve Woodward
@warpdaddy
Brilliant thread! We used to say to ourselves that strategy is nothing more than a series of tactical hacks. Thanks for the great step by step explanation of the issue and potential solutions!
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