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[Luis Antoniosi (CoCoDemus)]

hell yeah, the 6309 can be considered 16-bit :D


On Fri, Apr 19, 2013 at 1:19 PM, Luis Antoniosi (CoCoDemus) <
retrocanada76 at gmail.com> wrote:

> 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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>> >>
>> >
>> >
>> >
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>> >
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>> >
>>
>>
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>
>
>
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> Long live the CoCo
>



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