Re: Proposed Assembler Commands

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.

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.

John


.

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