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[OM] 32 Bit Processors [Was: an Albert intervention]

Subject: [OM] 32 Bit Processors [Was: an Albert intervention]
From: Jan Steinman <Jan@xxxxxxxxxxxxxx>
Date: Wed, 3 Sep 2003 09:37:04 -0700
From: Andrew Dacey <frugal@xxxxxxxxxxxxxxx>
>Subject: Re: [OM] Re: an Albert intervention
>
>On 9/3/03 3:48 AM, "Jan Steinman" <Jan@xxxxxxxxxxxxxx> wrote:
>
>> What are 16 bit apps? Apple users have never had to deal with such things --
>> all Mac programs were always 32 bit.
>
>This isn't true. 32-bit was mostly added in system 7 if memory serves.

I'm certain you're mistaken. The Motorola 68000 chips were 32 bit processors 
from Day One. (I did several years of 68000 assembly code, so I know!) If you 
think I'm wrong, I'll go in the garage and pull out the inch-thick processor 
manual.

What you may be thinking of is addressability issues. Up until the 68020, this 
processor family could only address 24 bits worth of memory (16MB). (Actually, 
the chip internally worked fine with large addresses, but only 24 address lines 
were brought through the package.)

Tricky programmers -- including some at Apple -- got in the bad habit of using 
the "missing" 8 bits in addresses for other things, such as garbage collection 
flags (which I did in a Smalltalk interpreter I wrote).

>Yes, most older apps worked fine but there were a
>couple ones that did have problems.

Agreed. But unlike Bill "640 kB aught to be enough for anyone" Gates, Apple 
quickly realized the need for more than 16 MB of RAM, and warned developers 
that such code would be unsupported in the future. By the time system support 
for large addresses came out (you may be right about System 7) there were very 
few applications that broke.

So perhaps this is picking nits, but I think it's a fine example of how Apple 
has consistently looked into the future and created a reasonable migration 
path. Two even finer examples were the relatively painless switch from 680x0 to 
Power PC processors, and the more recent switch to Unix.

It can be argued that Microsoft has also successfully changed the roots of 
their OS in moving from Windows 3/95/98 to NT/2000/ME/XP. (In fact, some argue 
that Microsoft changes their OS roots every other year... :-) But I don't 
believe any company has so successfully moved such a large installed base 
between different, incompatible processors as did Apple when moving from the 
680x0 to PowerPC.

(Yea, I know IBM used a software processor emulator in their 360 or 370 line, 
but that wasn't the same magnitude.)

>Note, I'm not slamming the Mac, I've used one since 1986 and it's still my
>primary desktop system at home (the only PC I currently own runs Linux).

Ah, another "Microsoft Free" zone? What's a virus without Microsoft to host it? 
:-)

Obligatory Olympus content: my E-20 does not run a Microsoft OS.

-- 
: Jan Steinman -- nature Transography(TM): <http://www.Bytesmiths.com>
: Bytesmiths -- artists' services: <http://www.Bytesmiths.com/Services>
: HTML email goes right in the trash! Turn off HTML if you want to email me.

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