On 2018-06-28, Pabst Blue Ribbon  wrote:

> Gareth's Downstairs Computer
>  wrote:
>
>> On 28/06/2018 17:17, Pabst Blue Ribbon wrote:
>>
>>> The Natural Philosopher  wrote:
>>>
>>>> On 27/06/18 21:00, Peter Percival wrote:
>>>>
>>>>> Gareth's Downstairs Computer wrote:
>>>>>
>>>>>> On 27/06/2018 20:23, Peter Percival wrote:
>>>>>>
>>>>>>> There seem to be a number of Forths that run on Raspberry Pi.
>>>>>>> Is it possible to say which one of them is best?
>>>>>>
>>>>>> The one that you write for yourself?
>>>>>
>>>>> Would that I could!
>>>>
>>>> An actual FORTH 'kernel' is very easy to write.
>>>
>>> I can be even more specific. On x86, 'kernel' is just 4 (four) processor
>>> instructions. The rest can be treated as 'library'.
>>
>> ISTR that on the PDP11, it was just a single instruction ...
>>
>> JMP @(r0)+
>
> I'm not familiar with PDP11. Four instructions I was referring to was
> complete NEXT statement from my simple Forth system. Single instruction
> versions that I've seen on Z80 were basically jumps to NEXT statement which
> was kind of outside of the rest of Forth (and which was still bigger than
> one instruction). I guess it all depends on which registers are used and
> which instructions available for the programmer.

You should study the PDP-11 instruction set.  The first time I disassembled
code that did stuff like this, I was dazzled by its elegance.  The Z80 doen't
come anywhere near.

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