[Coco] assembly questions?

[Mark Marlette]

At 04:27 PM 7/23/2004 -0400, you wrote:

James,

To date it is still a premier 8 bit processor. Not fair to compare it to 
today's technology. As you well know the '09 was the stepping stone for the 
68k.

Seems like we have a pretty good tech base here. I suggest that we have 
some people step forward and take the challenge of doing some of these 
projects. They would be GREAT, no doubt.

What Boisy and I do...Dream it, then make it happen. Takes time but very 
well worth it.

Regards,

Mark
Cloud-9



>Mark
>
>The Z8 series has 256 registers.
>
>The 68K series has 16 registers.
>
>Xilinx has their Pico/Micro Blaze processors that fit into their
>CPLD/FPGAs and can have up to 256 registers.
>
>Still registers to have registers is a waste of space. Persoanlly if you
>want a 16 bit process then use a 68K series or Intel.  The 6x09 is a
>nice 8 bit  processor and can still do a lot of neat things. If there
>were anything that one could do if going to FPGA, is to do more
>integration. Putting timers and I/O ports would be nice. For what I
>would like to see is a PWM section like in the 68HC11K series
>processors. Even an SPI or USB on board would be nice.
>
>james
>
>On 23 Jul 2004 at 14:34, Mark Marlette wrote:
>
>Date sent:              Fri, 23 Jul 2004 14:34:32 -0500
>To:                     CoCoList for Color Computer Enthusiasts
><coco at maltedmedia.com>
>From:                   Mark Marlette <mmarlett at isd.net>
>Subject:                Re: [Coco] assembly questions?
>Send reply to:          CoCoList for Color Computer Enthusiasts
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> > At 11:38 AM 7/23/2004 -0700, you wrote:
> >
> > Kevin,
> >
> > Lack of registers? What are use to programming on?
> >
> > Do you have VHDL training or experience? If so where?
> >
> > Curious.
> >
> > Regards,
> >
> > Mark
> > Cloud-9
> >
> >
> > >Hi,
> > >
> > >         The speed of these probably isn't that crucial since there
> > >         are
> > >so few registers to transfer between (amongst?). If I ever find a job
> > >I think I am gonna start with that 6809 VHDL core someone did and
> > >create the 6909.  One thing I think I'll include is a set of shadow
> > >registers and some special FAST tfr and exchange instructions to get
> > >at them. Kind of like a high speed register cache. Probably also need
> > >a context save instruction. And maybe some burst bus modes for some
> > >caches. And an instruction cache. And a stack cache (to speed up
> > >stack operations). And a 16-bit internal bus. ...
> > >
> > >         I am working on an assembly port of the old X maze program.
> > >         The
> > >lack of registers has been ... constantly annoying.
> > >
> > >                                   kevin
> > >KnudsenMJ at aol.com wrote:
> > > >
> > > > Thanks -- I myself have always wondered why TFR and EXG were so
> > > > slow! Part of the problem seem s to be always treating them as
> > > > 16-bit operations, so TFR A,B takes as long as TFR X,Y.
> > > >
> > > > And the other is using that internal temp reg, which turns out not
> > > > to be needed -- see below.
> > > >
> > > > In a message dated 7/23/04 7:53:52 AM Eastern Daylight Time,
> > > > jdaggett at gate.net writes:
> > > >
> > > > > with the TFR instrtruction the third and fourth cycle write R1
> > > > > to a temp register internally. On cycle 5 and 6 the temp
> > > > > register is written to R2.
> > > >
> > > > This sounds like an explanation I heard years ago, but below we
> > > > see the
> > > temp
> > > > wasn't needed. . .
> > > >
> > > > >  With the EXG instruction the third and fourth cycle writes R1
> > > > >  to the
> > > temp
> > > > > register.
> > > > >  On the fifth and six instruction the contents of R2 is written
> > > > >  to R1. On
> > > > the
> > > > > seventh  and eighth cycles the temp register is sritten to R2.
> > > >
> > > > Since R2 was written directly to R1, the TFR instruction could
> > > > have
> > > bypassed
> > > > the intermediate register too.  But I guess this implementation
> > > simplified the
> > > > control sequencing.  Remember, the 6809 was, and remains, the most
> > > > sophisticated 8/16-bit micro ever made -- or darn close to it.
> > > >
> > > > Thanks again for the details.  BTW, does the 6309 cut out any of
> > > > these intermediate steps?  Maybe use a 16-bit internal bus?!?
> > > > --Mike K.
> > > >
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