Re: Proposed Assembler Commands

On Sat, 30 Apr 2005 20:19:24 -0700, John Larkin wrote:

> On Sat, 30 Apr 2005 22:40:35 -0400, keith <krw@xxxxxxxxxx> wrote:
>
>>On Sat, 30 Apr 2005 18:11:23 -0700, John Larkin wrote:
>>
>>> On Sat, 30 Apr 2005 22:45:45 +0100, Pooh Bear
>>> <rabbitsfriendsandrelations@xxxxxxxxxxx> wrote:
>>>
>>>>Mike Monett wrote:
>>>>
>>>>> To All,
>>>>>
>>>>> Microprocessors have become so simple that it seems anyone can program
>>>>> them nowadays. But think of what it was like when the first processors
>>>>> came out and you had to program around noisy circuits and unreliable
>>>>> memory.
>>>>
>>>>Rumour has it that the 6800 had an undocumented instruction.
>>>>
>>>>HCF - Halt and Catch Fire
>>>>
>>>
>>>
>>> It probably didn't work. The 6800 was an n-channel depletion-load
>>> chip. You need CMOS to start a decent blaze.
>>
>>Hmm, I thought Moto and Intel were all p-channel at that time.
>>
>
> The 6800 was a 5-volt-only chip, all n-channel, dynamic logic I think;
> the p-ch chips had a weird negative supply, -12 or something.
>
> The only nasty part about the 6800 was that you had to externally
> generate a 2-phase clock that had some (for the time) nasty swing,
> edge rate, and non-overlap limits. The 6801/2/3 and later stuff was a
> lot easier to clock.

That wasn't unusual, at the time. The 8085 had similar issues.

> I once wrote an RTOS for the 6800, which was tricky because the stack
> operations were primitive. We included a reentrant floating-point
> package and token ring LAN (invented independently!) and it worked
> pretty well in process control apps.
>
> I always liked the Moto instruction sets. The Intel stuff has always
> seemed klugey and disorganized to me. So, we all wound up with the
> worst instruction set and the worst OS the industry could invent.

The Intel instruction set never bothered me, in fact I rather liked it.
Moto was too easy. ;-) I did like processors with more index
registers though. The one I think is unnecessarily weird is the 8051.
After ~20 years it still lives, so...

--
Keith

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