"John Rumm" wrote in message
o.uk...
On 25/10/2011 23:36, dennis@home wrote:


"Tim Streater" wrote in message
...
In article om,
"dennis@home" wrote:

"Tim Streater" wrote in message
...
In article m,
"dennis@home" wrote:

"Steve Firth" wrote in message
-september.

org
...
"dennis@home" wrote:
[snip]
If only Apple had allowed the clones to build Macs back in the
80s

yes we would still be stuck with an OS that didn't even do
virtual memory.
Windows did that for years before macOS.

No that's bull****. It would have been accurate had you said
that Windows
had protected memory before MacOS.

Well that's not surprising.. it wasn't until the 68030 series came
out that there was a working MMU to run the protection and
coincidently support paging and VM.
That is true for Motorola CPUs as used by Apple.

Mmmm no (again). The 030 was the first in the 68k line to have an
*on-board* MMU. You could perfectly well use a 68020 and use the
68851 MMU as a co-processor with it.

Which MacOS used one of those?

The later versions of classic MacOS, with virtual memory, would
certainly have run on an 020 Mac with MMU.

Anyway they didn't work very well.

Do you mean the 020? (Used in the TGV and Eurofighter according to
WinkyPedia). Or the MMU.

Well its pretty obvious from what I wrote.
maybe your MMU is also defunked?


Having written a tiny OS for the 68000 (see
http://www.clothears.org.uk) I can state that it's a much better
processor than the 8086 ever was. Just a shame that the 68008 wasn't
out in time for IBM to use in the original PC instead of the 8088.

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...

Segmented architecture, 16 bit registers and not many off them, loads of
hard coded use cases for various registers, weak stack handling, lame edge
sensitive interrupt controllers and prioritisation.

All of which still worked if you knew how to use them.


compared with flat memory, 32 registers, orthogonal design etc

No interrupt controllers for the 68000 (at least not when I was designing
8086 stuff, it was early as they hadn't even done the 8088 then, the PC
hadn't been invented either).
BTW the 8086 instructions were no worse than the 68000, you could do most
things without resorting to the short instructions.


The 80186 board I designed was programmed using PL/M and used RMX86.

It was much easier.

Than what? PL/M was better than Intel assembler granted (especially if you
had to use Intel's DOS based tools which were bug city). '186 cleared away
a few peripheral chips and was favoured by hardware guys who could not
work out how to do address decoding logic that worked, but the performance
was poor in comparison to 68K.

However it was cheap and made quite a nice controller for an X25
communications board.