[Coco] Glenside website (new & old)

[Luis Antoniosi (CoCoDemus)]

6309  doesn't count :P


On Fri, Apr 19, 2013 at 1:17 PM, L. Curtis Boyle <curtisboyle at sasktel.net>wrote:

> Do you mean like ANDD #$5555, as an example?
>
> L. Curtis Boyle
> curtisboyle at sasktel.net
>
>
>
> On Apr 19, 2013, at 11:03 AM, Luis Antoniosi (CoCoDemus) wrote:
>
> > You forgot the full 16-bit ULA. The x86 can perform a 16-bit bitwise AND,
> > OR, NOT while the 6809 can't.
> >
> >
> >
> > On Thu, Apr 18, 2013 at 11:30 PM, Lothan <lothan at newsguy.com> wrote:
> >
> >> From: Arthur Flexser
> >>
> >> I always wondered why the CoCo is referred to as an 8-bit machine,
> >>> whereas the original IBM PC, which also had an 8-bit bus and 16-bit
> >>> registers, was consistently referred to as a 16-bit machine.
> >>>
> >>> Art
> >>>
> >>
> >> As I recall, the only difference between the 8088 and the 8086 is that
> the
> >> 8088 had an 8-bit external data bus whereas the 8086 had a 16-bit
> external
> >> data bus. Internally, the data bus is 16 bits. The 20-bit address and
> 8- or
> >> 16-bit data bus used the same pins so memory access was a lot slower
> than
> >> on other processors. The only advantage to this approach is that Intel
> >> could squeeze it into a 40-pin DIP.
> >>
> >> Overall, the 8088/8086 had four 16-bit accumulators (or eight 8-bit
> >> accumulators), two 16-bit index registers, two 16-bit stack pointers,
> four
> >> 16-bit segment registers, and a 16-bit instruction pointer. The only
> thing
> >> here that wasn't already in the 6809 are three extra accumulators and
> the
> >> segment registers.
> >>
> >> Looking at it from this perspective makes me ask the same question. Both
> >> the 6809 and 8088 had an 8-bit external data bus and both were
> essentially
> >> 16-bit internally.
> >>
> >> This does raise a question, though. The only real advantage to the 8088
> is
> >> that it had segment registers that were used to augment the 16-bit
> >> instruction pointer register to develop a 20-bit physical address ((CS *
> >> 16) + IP). As much as I despise the 8088's segmented architecture, it
> makes
> >> me wonder what might have happened if Motorola or Hitachi had bolted on
> a
> >> couple of segment registers to the 6309 to give it an effectively flat
> 1MB
> >> address space.
> >>
> >> I remember back in the day the 80x86 architecture did not support
> >> position-independent code (and still doesn't to this day as far as I'm
> >> aware) and Windows didn't support hardware task switching, both of which
> >> were directly supported by OS-9 on the 6809 way back in the early '80s.
> >> Offhand, I'm thinking Windows Me still relied on the message pump for
> task
> >> switching and didn't switch to a hardware timer until Windows 2000 on
> the
> >> Pentium processor.
> >>
> >>
> >> --
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> >> Coco at maltedmedia.com
> >> http://five.pairlist.net/**mailman/listinfo/coco<
> http://five.pairlist.net/mailman/listinfo/coco>
> >>
> >
> >
> >
> > --
> > Long live the CoCo
> >
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> >
>
>
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>



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