🚀 go-pugleaf

On 2018-08-13 09:56, Questor wrote:
> On Sun, 12 Aug 2018 15:20:18 -0000 (UTC), John Levine <jo...@taugh.com> wrote:
>> In article <0897e059-0b26-4334...@googlegroups.com>,
>> Quadibloc  <jsa...@ecn.ab.ca> wrote:
>>>>> sorry when it was canceled, although I suspect it would have been difficult
>>>>> to expand the architecture to larger memory sizes.
>>>
>>>> We don't have to guess.  They did expand the addressing for the DEC-20
>>>> and it was pretty ugly. ...
>>
>>> I think it was ugly too; but I suppose that it could still be said that if the
>>> memory expansion method actually used was a kludge, that doesn't prove th at
>>> something better might not be possible.
>>
>> The people who did it were pretty smart.  An obvious alternative would
>> be a mode bit, like 16 vs 32 bit segments on the 386, and different
>> instruction formats, but if it's not backward compatible with 18 bit
>> code, you might as well switch to a Vax, which is what everyone did.
>>
>> The Vax was a mistake, too, beautifully optimized for a hardware and
>> software environment that was immediately obsolete, but that's a
>> different argument.
> 
> Possibly a result of trying to maintain a bridge to the PDP-11 world.

I'd disagree. The reason for most of the things in VAX was a result of 
memory being expensive, and people programming in assembler. So, you 
optimized the machine for being able to write programs that used as 
little memory as possible. There are lots of things in the VAX that 
comes from this. And it's definitely targeted at people still writing 
programs in assembler.

But, as mentioned, this was just at the time when this was all becoming 
obsolete. Memory prices continued to drop, while sized grew. Which meant 
that the whole effort at being memory efficient was moot. And people 
started writing less and less in assembler. Instead it started becoming 
more relevant how to make things faster and simpler, memory be damned.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: b...@softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol