[Coco] 16550 wasRe: RS232 paks

[Mark Marlette]

Gene,

I am glad that your memory has returned on this. :)

Darn it, being arrogant...Again......

Regards,

Mark
Cloud-9


At 3/5/2009 10:54 PM, you wrote:
>On Thursday 05 March 2009, Bob Devries wrote:
> >Of course, I have no idea exactly what the THROUGHPUT was in CPS with that
> >setup.
> >
>When I was working on rzsz-3.36 last, the optimized version everybody should
>have by now, using hardware flow control, could transmit to an amiga 
>at around
>740 cps with both sides set to 9600 baud.  In fairness to the flow control
>problems in the 6551, the amiga could of course keep up with the coco so the
>flow control never activated to trigger the bug under those 
>conditions.  So of
>course that bug never stuck up its hand in my tests.  That would only show up
>when the target machine was slower than the coco.
>
>Conversely, with the amiga sending to the coco, the flow controls 
>were used to
>slow the amiga down, and again the average speed was in the 735 cps 
>area.  And
>it was sustained over files of nominally a megabyte.  Only 
>noticeable slowdown
>was those created by the no-halt controller if I was writing to a floppy, but
>usually I used my hard drive or the ramdisk I wrote since my coco3 
>has a 2 meg
>kit in it and I can instantly (a few hundred milliseconds) set it up at up to
>about 1.7 megs max but usually for 1.5 megs.
>
>x and y modem, with their much simpler and faster error checking, 
>can run lots
>faster than that.  The speed killer in rzsz is the crc checking, 
>done on a per
>byte basis as the byte comes in or goes out.  Someday, someone should convert
>that to checking just one 256 byte buffer at once, it should at least triple
>rzsz's speed in cps.
>
>Those speeds above were obtained with the crc table lookup method.  Using
>rzsz's original crc method slowed it by a bit more than half, to around 330
>cps both ways, so that table lookup was a huge improvement right there.  Now
>it needs to be converted to doing that loop once, over a full or partial
>buffer.  I believe that would get it nicely above 960 cps (9600 baud).
>
>Anyway, those are the figures to shoot at, have fun, the code _is_ out there.
>
>--
>Cheers, Gene
>"There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
>-Ed Howdershelt (Author)
><``Erik> 18,446,744,073,709,551,616 is a big number
>
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco
>
>No virus found in this incoming message.
>Checked by AVG - www.avg.com
>Version: 8.0.237 / Virus Database: 270.11.8/1985 - Release Date: 
>03/05/09 07:54:00