🚀 go-pugleaf

On Sunday, in article <911172839snz@alquds.demon.co.uk>
     News01@alquds.demon.co.uk "Shakib Otaqui" wrote:

>     Ian's question, in a private email, about Windows possibly 
>     buffering the port and upsetting the timing prompted some 
>     tests.  Ever since Win 3.x days, I've had "com2buffer=16384" 
>     in the [386Enh] section of system.ini.  It has enabled me to 
>     put a DOS comms session in the background and use fairly CPU-
>     and disk-intensive tasks in the foreground with hardly any 
>     hardware overruns -- in fact, the only way I've found to get 
>     them is to use Windows mark/copy in a DOS window, which seems 
>     to hog the machine.
> 
>     I tried the PUT command after commenting out the com2buffer 
>     line and rebooting and it worked fine.  I put it back with a 
>     1024-byte buffer and Yan blew up as before, so it does look 
>     as if buffering is the problem here.

Thanks for that.

I haven't got round to looking at the code yet and I can't test any of 
it, but here's an initial theory which assumes fast (200+Mhz clock) 
hardware and a buffered COM port with a big buffer. With a small file, 
less than the buffer size, KA9Q could see an essentially instantaneous 
transfer and, more ominously, a zero transfer time. When it tries to 
calculate the rate...

YAN, using it's bytecout progress display, might get similar problems 
with any file. Even on my paltry hardware I've seen initial progress 
rates around 100k/sec. With a bigger buffer and especially if the file 
was sitting in a disk cache it could push the laws of physics :)

The second scenario is easily tested by seeing how the hash or no 
progress display gets on with files bigger than the COM port buffer.
The first might be suggested if very small files blow it while big files 
don't.
Dunno if any of this holds water, but when I woke up this morning it 
looked bloody plausible :)
Maybe I need more sleep.
And to get out more.

Ian.
-- 
  |  Ian Smith             |  "The Moving Finger writes;
  |  ian@isis.demon.co.uk  |   and, having writ, Moves on."