Why do PCs load their boot sector at 7C000h linear?

Re:Why do PCs load their boot sector at 7C000h linear? by MatthewWilkes on Saturday September 26, 2015 @11:35AM (#10283346)

Can someone provide a TL;DR? I'm finding it very hard to understand the article.

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Re:Why do PCs load their boot sector at 7C000h linear? by Dylan16807 on Saturday September 26, 2015 @12:02PM (#10283421)

IBM's BIOS put the boot loader at the end of the minimum amount of memory at the time (32KB). 7C00-7DFF get the boot sector, and 7E00-7FFF are scratch space.

Also once upon a time SCP tucked it into 0200-03FF because that ram was otherwise unused.

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Re:Why do PCs load their boot sector at 7C000h linear? by yuhong on Saturday September 26, 2015 @02:18PM (#10283913)

the minimum was 16KB I think (they used 4116s).

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Re:Why do PCs load their boot sector at 7C000h linear? by Dylan16807 on Saturday September 26, 2015 @02:27PM (#10283948)

Well, I'm just summarizing.

> "DOS 1.0 required a minimum of 32KB, so we weren't concerned about attempting a boot in 16KB."

> (Note: DOS 1.0 required 16KiB minimum ? or 32KiB ? I couldn't find out which correct. But, at least, in 1981's early BIOS development, they supposed that 32KiB is DOS minimum requirements.)

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Re:Why do PCs load their boot sector at 7C000h linear? by yuhong on Saturday September 26, 2015 @02:29PM (#10283960)

There are different configs of IBM PC, the cheapest which relied on the ROM BASIC and cassette tape.

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Re:Why do PCs load their boot sector at 7C000h linear? by Dylan16807 on Saturday September 26, 2015 @02:30PM (#10283963)

Right, but we're worried here about the ones booting DOS, while they were designing this.

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