[Coco] RS DOS RS232 application?

[Gene Heskett]

On Thursday 14 April 2016 22:42:10 Dave Philipsen wrote:

> Have you compared the pshs/u puls/u instructions for moving data
> quickly?

No I haven't Dave. I did look at the cycle counts a long time ago, and 
ldq/stq were a fewer cycles less on the 6309 as it skipped the 2nd 
instruction fetch on the 6309.  And moved 4 bytes at a time, so I just 
used the 6809 equ that moved 2 bytes at a time if that is what its 
running on. For incoming or outgoing data thru a 6551, if a 4 byte fifo 
in hardware could be built that only its driver knew about, that would 
handily demolish the timeing requirement of clearing the 6551 read 
register before the next byte was clocked in.  Frameing errors would 
melt away till at least 2x the speed on a 6809.

This is also a major roadblock to the use of rzsz at higher speeds 
because the current implementation is a one byte at a time monster.  And 
it cannot deal at all with a data window bigger than 256 bytes.  I 
should have been working on Tim K.'s code, which I think could handle 
the bigger block sizes.  Putting the table lookup cnc method into that 
should have resulted in at least a 2x speed improvement like it did for 
rzsz.  But we have better phone lines today, so its extreme error 
correction ability that results in the speed limit, is IMO wasted.

> Dave
>
> On 4/14/2016 7:14 PM, Gene Heskett wrote:
> > On Thursday 14 April 2016 19:58:35 RETRO Innovations wrote:
> >> I would like to test out a mod to my RS232 pak to bring it up to
> >> 230kbps.  Is there a simple app around that has source so I can
> >> modify it to do 230kbps on my rs232 pak and test?  Or,
> >> alternatively, is there a simple terminal that I can run to test
> >> out the various existing bps rates?
> >>
> >>
> >> Jim
> >
> > Unless you have huge buffers, big enough to contain the whole
> > transmission, the coco cannot move more than about 90k a second. 
> > That corresponds to the megaread times I was able to get from myram,
> > of 11 seconds for a megabyte on a 6309, and just over 13 seconds on
> > a 6809, each using the fastest way to move data that exists on those
> > 2 processors. For the 6809, thats (after the transfer is setup)
> > ldd,x++; std, y++, or for the 6309, ldq ,x++;stq ,y++ (IIRC).
> >
> >> --
> >> RETRO Innovations, Contemporary Gear for Classic Systems
> >> www.go4retro.com
> >> store.go4retro.com
> >
> > Cheers, Gene Heskett


Cheers, Gene Heskett
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