🚀 go-pugleaf

There have been several comments regarding the speed of reading and
writing on the ST floppy drives. One person who has looked into the
problem and done something about it has commented on it within our
internal notes files here at Digital. He has been involved in the
development of Sedt (now in Beta test), a screen editor that is a
superset of the Digital supported EDT text editor. 

Exerpts from his notes follow...
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                I have  spent  a  lot of time trying to improve the speed
        that Sedt loads  and  saves files at.  By now it's getting pretty
        decent.  I did  discover  that  the  problems indeed are the ones
        covered in the previous notes.
        
                The  first  problem  is that it's DEATH to use the higher
        levels  of  C  file  routines  in  ALCYON  C.    Stream  I/O runs
        incredibly slow.    I currently use the next lower level and will
        migrate to the lowest (firmware).
        
                The other problem  is  interleaving.    I  bought a SUPRA
        20meg disk which they had mistakenly formatted with an interleave
        factor of 2.  Last  weekend  I  reformatted  it  with 3 and saw a
        marked improvement in speed.  I  guess that when you only get one
        sector per revolution it really is slow.    It  must  be the same
        problem with the floppies.
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                By doing all the formatting myself and experimenting with
        different transfer buffer sizes I was able to greatly improve the
        floppy read/write times.   Sedt  now  loads  and saves files from
        floppies between two and three  times  faster  than  Micro EMACS.
        For any kind of read/write to  or  from  floppies  transfer rates
        drop  dramatically  as  the  buffer  length  increases  and  then
        flattens out around 6K buffers.  After that  is has a tendency to
        go up and down a bit because of interleave  delays.   From this I
        am 100% certain that the performance problems are caused by  poor
        interleaving of sectors on the floppy.
        
        Anker


     /Don Peters, Digital, 617-689-1242/

        ...decvax!decwrl!dec-rhea!dec-pulman!peters