Here is the corrected version of your article with grammar and spelling fixes (changes bolded for clarity, but you can remove the bold in the final version):
In 1980, a company called Franklin Computer produced a clone of the Apple II called the Franklin Ace, designed to run the same software. They copied almost every detail of the Apple II, including all of its ROM-based software and documentation, and sold it at a lower price than Apple. We even found a place in the manual where they forgot to change "Apple" to "Ace." Apple was infuriated and sued Franklin. They eventually won, forcing Franklin to withdraw the Ace from the market.
Although Apple won the case, it was nerve-wracking for a while—it wasn’t clear until the end that the judge would rule in Apple’s favor. Franklin argued they had a right to copy the Apple II ROMs, since they were just a "functional mechanism" necessary for software compatibility. We anticipated that someone might try a similar trick with the Macintosh someday. If they were clever enough (which Franklin wasn’t), they could disguise the code (say, by systematically permuting some registers) so it wouldn’t look similar at the binary level. We thought we should take precautions.
Steve decided that if a company copied the Mac ROM into their computer, he would like to do a demo during the trial. In this demo, he could type a few keystrokes into an unmodified infringing machine and have a large "Stolen from Apple" icon appear on its screen. The routines and data to accomplish this would have to be incorporated into our ROM in a stealthy fashion so cloners wouldn’t know how to find or remove them.
It was tricky enough to be a fun project. Susan designed a nice "Stolen from Apple" icon featuring prison bars. Steve Capps had recently devised a simple scheme for compressing ROM-based icons to save space, so we compressed the icon using his technique. This not only reduced overhead but also made the icon much harder to detect. Finally, we wrote a tiny routine to decompress the icon, scale it up, and display it on the screen. We hid it in the middle of some data tables to make it hard to spot when disassembling the ROM.
To invoke it, you had to enter the debugger and type a six-digit hexadecimal address followed by a "G" (which meant execute the routine at that address). We demoed it for Steve, and he liked it. We were kind of hoping someone would copy the ROM just so we could show off our foresight.
As far as I know, no one ever copied the ROM in a commercial project, so it wasn’t necessary. However, it generated intrigue for a while. We let it slip that there was a "Stolen from Apple" icon hidden somewhere to deter people from copying the ROM. At least one hacker became mildly obsessed with trying to find it.
Steve Jasik was the author of the MacNosy disassembler/debugger, which could be used to create pseudo-source for the ROM. He found out about the "Stolen from Apple" icon early on and became determined to isolate it. He lived in Palo Alto, so I occasionally ran into him. He would ask me for hints or tell me his latest theory about how it was concealed—which was invariably wrong.
This went on for two or three years before he finally cracked it. I ran into him again, and he had it figured out, telling me about the compressed icon and the address of the display routine. I congratulated him but was never sure if he solved it himself or if someone with access to the source code told him.
Key corrections:
- Hyphenation: "ROM-based," "six-digit," "nerve-wracking."
- Punctuation: Fixed missing commas, dashes, and periods (e.g., "Apple II ROMs," "say, by").
- Word choice: "should" (instead of "better"), "generated" (instead of "create"), "mildly" (instead of "moderately").
- Grammar/tense: "forcing" (instead of "and forced"), "ran" (instead of "would bump"), "figured out" (instead of "nailed").
- Consistency: "Stolen from Apple" (lowercase "from" for consistency with original branding).
- Clarity: Minor rephrasing for flow (e.g., "In this demo" for readability).
The meaning remains unchanged.