3 Nov
1998
3 Nov
'98
5:11 a.m.
UKers should check out the 50th issue of PC Pro. It has a
feature on old computers. I had a quick look and saw
mentions of the Osbourne 1 and some other systems.
Sean 'Captain Napalm' Conner wrote:
The apps I have for both MS-DOS and the Amiga tend to
be fairly robust
and
less crash prone than for systems that have memory
protection, I suppose
becuase with memory protection it's easier to write sloppy code that won't
bring down the system [2] so not as much effort is taken in writing solid
code.
There is an application currently in development for the "Classic Amiga"
line at the moment that promises to bring memory protection to the OS. This
is quite an amazing feat when you consider that it is a 3rd party addon and
has been thought impossible for years. I just hope it is included in AmigaOS
3.5.
John Foust muttered:
I think this is crucial for those who wish to
understand why the Amiga
didn't live forever: although it was 32-bit, its architecture had a deep
reliance on wide-open shared memory, preventing it from reaching the
next level of robust behavior. Tricks like "Enforcer" certainly helped
developers write safer code once the 68020 came along, but it was too
little, too late.
Indeed. Particularly the lack of Unified Memory Access, restricting the user
to a maximum of 2Mb Chip RAM (although UAE somehow allows up to 8Mb chip
RAM). It can be improved on by adding a graphics card which will take the
strain of the display off the custom chips. Once you begin to add PPC
processors the task switching between the two processors, 68k and PPC really
begins to reduce performance.
D. Peschel spoke unto the masses:
I knew there was a reliance on shared memory, but I
didn't know it was that
deep. Are you talking just about the custom hardware? (When the Amiga was
new, Amiga clearly had to work its butt off it get the chips to perform so
well -- making them squeeze through an MMU while doing DMA was obviously
not
practical. Do you know if they even had plans to add
memory management?)
The original Amiga Corp considered using MMU but ( I think RJ Mical stated
in an interview) that it would have made multitasking in his words, "a lot
hairier." It would have slowed down the Amiga considerably when it was first
released. With current technology it is possible to use the MMU to implement
third party VMM, as well as Kickstart mappers. Some games and applications
also use it. Quake being one of the most notable.
I'm tempted to say that after its initial success,
Amiga rested on its lau-
rels and didn't try to improve the hardware for a long time (and they only
sort-of tried to improve the software). I don't know if it's *true*, but
it's *tempting*. Then they got around to the AGA graphics hardware which
is much better, except they were never able to catch all the bugs!
Commodore rested on its laurels and the management made some classic
mistakes. Cancelling AAA and when it was almost finished and releasing the
A4000 being noteable (the A3200 were much better and included DSP as
standard). The AGA
chipset still ran at 7.14MHz like its predecessors.
Now they want to combine the old architecture with
fancy new CPU's and
hope-
fully memory management -- good luck but it sounds like
a lot of work.
Do you know if they're trying for software compatibility?
The latest release of AmigaOS, version 3.5 is due to ship early 1998 and has
over twenty developers working on it. This should make a lot of the third
party addons standard as part of the OS. Most Amigas nowadays are expanded
so much that much of the design is unused. Even on my relatively
underpowered A1200, the 68020 is ignored in favour of the 68040 that is
present on my accelerator card. The OS upgrade is also going to be quite
revolutionary by Amiga standards, requiring a minimum of a 020 processor
with 4Mb. Considering that AmigaOS 3.1 could be run on an A500 this is quite
a development.
Amiga Inc claim that the OS upgrade will be 100% compatible with AmigaOS 3.1
although I have my doubts. They have also stated that AmigaOS 5 that will be
released at the end of 1999 will be compatible with AmigaOS 3.5. Whether
this actually comes to pass is another matter.
There is another lesson here, I think. It's one
reason why adaptation has
been or will be so hard -- ANY decision you make about a system, good or
bad,
especially bad, will affect the system for longer than
you think.
Only recently has Apple finally rid themselves of most of the 68k code in
their OS. Until MacOS 8 much of the OS was run under emulation.
Regards,
Gareth Knight
Amiga Interactive Guide
http://welcome.to/aig