On 26/10/2011 02:05, Jules Richardson wrote:
On Wed, 26 Oct 2011 01:46:55 +0100, John Rumm wrote:
AFAICS there wasn't much in it.
I wrote in 8086 assembler for the 8086 board I designed. It wasn't any
more difficult than assembler for the 68000.

You are having a laugh...

I actually assumed he was just trolling, because surely even he isn't
*that* crazy.

x86 was awful, it really was. Didn't its choice largely stem from IBM

Was? it still is (from a developers point of view).

using it on an earlier product? If only they'd gone for m68k instead, or
even the ns32k...

IIUC, the original PC was needed quickly to fulfil what IBM saw as a two
year gap in the market, after which they would have replaced it with a
"proper" solution. Hence they farmed out the design to one of their
research labs at the fringe of the organisation, told them to work fast,
ignore the normal company way of doing things and get a product built
quick. That basically meant taking ready to go designs wherever they
could. So processor and memory architectures straight off Intel data
sheets, disk interface from Shugart ones etc. The only really novel bit
of engineering was hooking it up to one of the famous IBM style
keyboards lifted from a selectric typewriter. (hence why the keyboard
controller chips on PCs carry out a whole bunch of unrelated activities
- it was the only bit being built from scratch, and so where most
missing functionality had to go!)

They wanted a 16 bit architecture, but were particularly attracted to
the 8088 because it looked like an 8 bit design externally. Hence a
cheap memory and bus design. It also had the option of going to proper
16 bit later without having significant any impact on software.

The rest is history...



--
Cheers,

John.

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