Discussion:
The 6809 and 680xx instruction sets
(too old to reply)
Jonathan de Boyne Pollard
2010-03-22 22:19:07 UTC
Permalink
I liked the 6809 instruction set, and *really* like the 68000
instruction set.
I'll second that (since no-one else in the thread has).
No-one?
OK. I spent a while once converting code from Z180 to 68HC11.
The 68- code consistently came out a few percent smaller and faster.
It seemed to be because of
* the dual A and B accumulators
* the more compact conditional branch coding.
? more compact coding for X register indexing. (Y/IY was about the same.)
My likes of the instruction set aren't based so much upon performance
data, but upon the other things mentioned elsewhere in this thread,
including the ease with which it was possible to convert from machine
code to assembly language, and the whole
let's-just-encode-all-registers-with-a-uniform-encoding idea. The
difference between X, Y, U, and S indexed and indirect addressing in the
6809 is a simple uniform set of two-bit patterns.
Peter Flass
2010-03-23 10:55:38 UTC
Permalink
I liked the 6809 instruction set, and *really* like the 68000
instruction set.
I'll second that (since no-one else in the thread has).
No-one?
I wasn't. I really like it too, but what's the point? Coldfire is a
stripped-down ISA. IIRC it doesn't include memory-management. Other
than that, where can I buy a 680x0 system today? I was sorry to see the
6800, and especially the 6809, lose out to the 8086, but Intel is like
Walmart - it's ***@p, but it's everywhere.
George Neuner
2010-03-23 18:26:02 UTC
Permalink
On Tue, 23 Mar 2010 06:55:38 -0400, Peter Flass
Post by Peter Flass
where can I buy a 680x0 system today?
There are industrial rack systems - VMEbus, BCN, BLN, etc. - that have
68K family processor boards available. Apart from utterly ridiculous
cost, the only real impediment is their snail-like performance ... the
fastest 68060 chips are 75MHz and I've never seen faster than 60MHz
from any CPU board vendor.

George
Bernd Felsche
2010-03-23 23:57:07 UTC
Permalink
Post by George Neuner
On Tue, 23 Mar 2010 06:55:38 -0400, Peter Flass
Post by Peter Flass
where can I buy a 680x0 system today?
There are industrial rack systems - VMEbus, BCN, BLN, etc. - that have
68K family processor boards available. Apart from utterly ridiculous
cost, the only real impediment is their snail-like performance ... the
fastest 68060 chips are 75MHz and I've never seen faster than 60MHz
from any CPU board vendor.
Industrial computers will always be at what domestic users consider
to be "utterly ridiculous cost". They are nevertheless built for a
far more harsh operating environment and with reliability as the
priority.

I wouldn't call a 68060 at 50 MHz "snail-like", having an Amiga
powered by one. It is more than adequate in the right system for an
application.

The real problem is that the amount of data with which people deal
with on a day to day basis is about 1000 times greater than what it
was 20 years ago. It now takes a megabyte to say what used to take a
kilobyte.

And the only time when people throw data away is when they upgrade
computers. New desktop computer systems come with half a terabyte of
storage capacity. And maybe a floppy drive for backups. :-)
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | If builders built buildings the way programmers
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George Neuner
2010-03-24 02:25:28 UTC
Permalink
On Wed, 24 Mar 2010 07:57:07 +0800, Bernd Felsche
Post by Bernd Felsche
Post by George Neuner
On Tue, 23 Mar 2010 06:55:38 -0400, Peter Flass
Post by Peter Flass
where can I buy a 680x0 system today?
There are industrial rack systems - VMEbus, BCN, BLN, etc. - that have
68K family processor boards available. Apart from utterly ridiculous
cost, the only real impediment is their snail-like performance ... the
fastest 68060 chips are 75MHz and I've never seen faster than 60MHz
from any CPU board vendor.
Industrial computers will always be at what domestic users consider
to be "utterly ridiculous cost". They are nevertheless built for a
far more harsh operating environment and with reliability as the
priority.
Agreed. But my impression was Peter was asking for personal use ...
else he'd already know such things were available.
Post by Bernd Felsche
I wouldn't call a 68060 at 50 MHz "snail-like", having an Amiga
powered by one. It is more than adequate in the right system for an
application.
I had 000 and 020 Macs and I worked with 040 and 060 in embedded
VMEbus systems. 68Ks are very nice chips to work with and I still
like them for embedded use. But for general computing they are now
woefully underpowered.
Post by Bernd Felsche
The real problem is that the amount of data with which people deal
with on a day to day basis is about 1000 times greater than what it
was 20 years ago. It now takes a megabyte to say what used to take a
kilobyte.
And the only time when people throw data away is when they upgrade
computers. New desktop computer systems come with half a terabyte of
storage capacity. And maybe a floppy drive for backups. :-)
Yup.

George

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