[Coco] 16550 wasRe: RS232 paks
mark at cloud9tech.com
Fri Mar 6 00:40:54 EST 2009
I am glad that your memory has returned on this. :)
Darn it, being arrogant...Again......
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
>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
>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
>it was sustained over files of nominally a megabyte. Only
>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.
>"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
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