On Wed, 10 Oct 2007 17:12:06 +0200, Jecel Assumpcao Jr wrote:

> Klaus D. Witzel wrote:
>> On Wed, 10 Oct 2007 12:35:20 +0200, Bert Freudenberg wrote:
>> > On Oct 10, 2007, at 11:54 , Klaus D. Witzel wrote:
>> >> On Wed, 10 Oct 2007 10:37:44 +0200, Bert Freudenberg wrote:
>> >>> It's incredibly flexible indeed, and goes back to the B5000 that
>> >>> inspired Smalltalk.
>> >>
>> >> Interesting. Having worked with almost all B5000 series and  
>> successors
>> >> and still working with them, what's the chunk format on them (besides
>> >> that it has no naked memory pointers, but descriptors)?
>> >
>> > Maybe I should have wrote "the idea goes back", not chunk format  
>> itself.
>> > The idea to have the data itself specify how to be processed comes  
>> from
>> > there - the tapes had a loader program in front that reads the rest of
>> > the tape. I don't know much about the details.
>>
>> Ah, the clear/start & halt/load tapes :) still in use in emergency
>> situations, when disks are down. Will tell my colleagues about
>> clar/start's usage in Smalltalk code file chunks :)
>
> I think Bert might have been thinking of the Burroughs 220 tape

EletroData's Datatron 220?

- http://special.lib.umn.edu/findaid/ead/cbi/cbi00090-036.xml

> format
> used in Air Training Command installation which was mentioned by Alan
> Kay in his "The Early History Of Smalltalk".

Thanks for the reference Jecel. Alas, the clear/start tapes (small+medium  
systems) and halt/load tapes (large systems) concept survived the whole  
Burroughs story and so have the chunks to which Bert referred to :)

> Since most problems in computing can be solved by adding another level
> of indirection, it might be nice to extend the chunk format so that when
> you got an error while trying to create a reader due to missing classes
> there were some hint on how to fix the problem automatically (by
> downloading another file).

Yeah, that's always fascinating with software: adding another level of  
complexity is always possible, whereas subtracting one might trouble you  
with existence problems :)

/Klaus

> -- Jecel
>
>