[Coco] RS DOS RS232 application?

[L. Curtis Boyle]

Yes, the “stack blasting” technique is by far the fastest way to move/copy blocks of contiguous memory around on a 6809. On the 6309, TFM is much faster than that.

L. Curtis Boyle
curtisboyle at sasktel.net



> On Apr 15, 2016, at 9:15 AM, Dave Philipsen <dave at davebiz.com> wrote:
> 
> 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
>> -- 
>> "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>
>> 
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