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On 02/22/07 22:35, Mike McCarty wrote:
> Ron Johnson wrote:
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>> On 02/22/07 10:43, John Hasler wrote:
>>
>>> Mike McCarty writes:
>>>
>>>> 8086 is 16 bit bus, 16 bit registers
>>>
>>> But with a bizarre segmentation scheme and a 20 bit address bus able to
>>> address 1MB.
>>
>>
>> But back in the day, with the limited silicon budget, segmentation
>> is a great way for a 16 bit system (that wants to maintain upward
>> compatibility with the 8080/8085) to address more than 64KB.
>
> Note that this was a certain type of pseudo asm source compatibility,
> not object compatibility.
And segmentation assisted that.
http://en.wikipedia.org/wiki/8086#Segmentation
One advantage of this unconventional memory scheme is
that programs could ignore the segments, and just use
plain 16-bit addressing, which allowed 8-bit software
to be easily ported to the 8086. The authors of MS-DOS
took advantage of this by providing an API very similar
to CP/M. This was important when the 8086 was new, because
it allowed many existing CP/M applications to be quickly
made available on the new platform. This greatly eased
the transition from 8-bit to 16-bit computer.
>> The 68K was/is still a much better architecture.
>
> Oh, please, not that flame war again.
Please, just for old-time's sake?
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