On 12/14/2021 8:38 AM, Marc Rintsch wrote: > 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 That was what I remembered. I guess I assumed that if someone was going to all the trouble to make a USR file, as opposed to a SEQ/PRG, they wanted some specific non standard format or use case. The challenge with this list is the balance of answering a question here without having to be pedantic about every small detail. My point was that SEQ/PRG files don't enforce any specific container format in the file, so you can open one and put whatever format you'd like into it, WAV or MP3 or TXT, etc. I called out USR separately, because I was afraid if I did not, someone would immediately question it's exclusion. But, except for the trivial use of USR (open 1,8,2,"file,u,w"), I'd expect folks to use it in a situation where they wanted lots of control over file use/format, and so it actually is a case where the format might matter. I'll concede on the specifics of USR files, but I hope my original point takes precedence. You can use a device that implements PRG and SEQ file access to store/load any file format you'd like, as groepaz originally noted. Jim -- Jim Brain brain_at_jbrain.com www.jbrain.comReceived on 2021-12-14 23:03:35
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