[Coco] 16/32 bit 6809 derivative

[Gene Heskett]

On Tuesday 26 September 2017 11:39:16 Dave Philipsen wrote:

> Gene, I dropped out of the CoCo scene after I wrote Supercomm so I
> didn’t follow the rzsz progress.  And I’m not that familiar with
> zmodem. Is the CRC calculation a fairly complex thing?  I found that
> with xmodem/ymodem it was faster to calculate the checksum/crc on the
> fly (byte for byte) because it didn’t increase the delay between the
> packets.  Is there a way to use tables instead of doing the
> calculations for CRC or perhaps a hybrid method that uses some tables
> and some calculations?
>
table crc is quite a few cycles per call faster, and with very little 
changing of the call syntax one could do the whole crc of a full 256 
byte packet in one call at the end of the packet before sending the ok 
ack.

Its the pc, including linux, that don't exactly follow the original idea 
as chuck wrote it at Omen Tech all those decades ago, so now we have to 
issue an invocation option to it to restrict it to a 256 byte packet. 
With that, and an actual working hardware 7 wire protocol for flow 
controls, I have moved disk images back and forth.  But somewhere in the 
extreme submodule craziness applied to nitros9 over the last 15 years, 
hardware xoff/xon flow controls now fail to work so the pc by default 
overruns the coco so bad the successful transfer rate can be as low as 
10 kilobytes an hour.  So there is ample blame to apply to both ends of 
the cable.

> Dave
>
> > On Sep 26, 2017, at 8:59 AM, Gene Heskett <gheskett at shentel.net>
> > wrote:
> >
> >
> > I had one more thing I was going to do to rzsz, convert the crc
> > calcs from byte for byte calls, with all the overhead that
> > represents, to one call over the whole buffer or part thereof for
> > the final packet, that alone might have sped it up enough it could
> > keep up with a 9600 baud link on a 6309.  But by the time I put
> > 3.3.6 out there, I was burned out for a while and it never got done.
> > My bad, it should have been done then.
> >
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> > soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > Genes Web page <http://geneslinuxbox.net:6309/gene>
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>