[Coco] RS DOS RS232 application?

[Dave Philipsen]

I just mentioned that because I remember doing some research a long, long time ago on how to clear a CoCo 3 graphics screen in the quickest way.  It seems like I ended up using pshu for that. If you think about it, a pshu is very similar to a std  ,x++  except that you can move more than two bytes at a time.

Dave Philipsen

> On Apr 15, 2016, at 1:43 AM, Gene Heskett <gheskett at wdtv.com> wrote:
> 
>> 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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> 
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