Re: Projects that take Commodore computers to 2021

On 14.12.21 13:48, groepaz_at_gmx.net wrote:
> Am Dienstag, 14. Dezember 2021, 13:37:25 CET schrieb Marc Rintsch:
>> On 14.12.21 11:23, groepaz_at_gmx.net wrote:
>>> ehrm. USR is exactly the same as PRG and SEQ, the only difference is one
>>> byte in the directory entry. They werent *that* uncommon either :)
>>
>> The DOS treats them the same, but many USR files are not written by the
>> DOS.  GEOS VLIR files are USR and structured not like PRG and SEQ.
> 
> And you can do exactly the same with PRG or SEQ (and there exist program that
> do). I wouldnt say "many are not written by the DOS" either - do you have
> another example than GEOS? :) What GEOS does isnt really "USR files" either,
> its just tagging a directory entry with USR - to the DOS those arent even

Of course you can do that with PRG/SEQ too, but you are not supposed to. 
  With USR on the other hand I always had the impression those are meant 
to ”go wild” like GEOS did.  „Inside Commodore DOS“ says „A user file 
may have the structure of either a sequential file or a program file if 
it was created by the DOS. It may be structured entirely differently if 
it was created using direct-access techniques described in Chapter 5.”

If there are USR files on a disk I'm cautious about making any 
assumptions about the structure unless I know for sure which program has 
written them/if this is a GEOS disk.

Ciao,
	Marc 'BlackJack' Rintsch
-- 
“It should be noted that no ethically-trained software engineer would
  ever consent to write a `DestroyBaghdad` procedure.  Basic professional
  ethics would instead require him to write a `DestroyCity` procedure, to
  which `Baghdad` could be given as a parameter.” -- Nathaniel Borenstein